Materials

17 pages, 3346 KiB

Open AccessEditor’s ChoiceArticle

The Use of 3D Printing Filaments to Build Moisture Sensors in Porous Materials

by Magdalena Paśnikowska-Łukaszuk, Joanna Szulżyk-Cieplak, Magda Wlazło, Jarosław Zubrzycki, Ewa Łazuka, Arkadiusz Urzędowski and Zbigniew Suchorab

Materials 2025, 18(1), 115; https://doi.org/10.3390/ma18010115 - 30 Dec 2024

Viewed by 678

Abstract

This study explores the application of materials used in 3D printing to manufacture the housings of non-invasive sensors employed in measurements using a TDR (Time Domain Reflectometry) meter. The research investigates whether sensors designed with 3D printing technology can serve as viable alternatives [...] Read more.

This study explores the application of materials used in 3D printing to manufacture the housings of non-invasive sensors employed in measurements using a TDR (Time Domain Reflectometry) meter. The research investigates whether sensors designed with 3D printing technology can serve as viable alternatives to conventional invasive and non-invasive sensors. This study focuses on innovative approaches to designing humidity sensors, utilizing Fused Deposition Modeling (FDM) technology to create housings for non-invasive sensors compatible with TDR devices. The paper discusses the use of 3D modeling technology in sensor design, with particular emphasis on materials used in 3D printing, notably polylactic acid (PLA). Environmental factors, such as moisture in building materials, are characterized, and the need for dedicated sensor designs is highlighted. The software utilized in the 3D modeling and printing processes is also described. The Materials and Methods Section provides a detailed account of the construction process for the non-invasive sensor housing and the preparation for moisture measurement in silicate materials using the designed sensor. A prototype sensor was successfully fabricated through 3D printing. Using the designed sensor, measurements were conducted on silicate samples soaked in aqueous solutions with water absorption levels ranging from 0% to 10%. Experimental validation involved testing silicate samples with the prototype sensor to evaluate its effectiveness. The electrical permittivity of the material was calculated, and the root-mean-square error (RMSE) was determined using classical computational methods and machine learning techniques. The RMSE obtained using the classical method was 0.70. The results obtained were further analyzed using machine learning models, including Gaussian Process Regression (GPR) and Support Vector Machine (SVM). The GPR model achieved an RMSE of 0.15, while the SVM model yielded an RMSE of 0.25. These findings confirm the sensor’s effectiveness and its potential for further research and practical applications. Full article

(This article belongs to the Special Issue 3D-Printed Composite Structures: Design, Properties and Application)

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14 pages, 2561 KiB

Open AccessEditor’s ChoiceArticle

Surface Hydrophilic Modification of Polypropylene by Nanosecond Pulsed Ar/O₂ Dielectric Barrier Discharge

by Yang Zhou, Zhi Fang, Yi Zhang, Tingting Li and Feng Liu

Materials 2025, 18(1), 95; https://doi.org/10.3390/ma18010095 - 29 Dec 2024

Viewed by 752

Abstract

Polypropylene (PP) membranes have found diverse applications, such as in wastewater treatment, lithium-ion batteries, and pharmaceuticals, due to their low cost, excellent mechanical properties, thermal stability, and chemical resistance. However, the intrinsic hydrophobicity of PP materials leads to membrane fouling and filtration flux [...] Read more.

Polypropylene (PP) membranes have found diverse applications, such as in wastewater treatment, lithium-ion batteries, and pharmaceuticals, due to their low cost, excellent mechanical properties, thermal stability, and chemical resistance. However, the intrinsic hydrophobicity of PP materials leads to membrane fouling and filtration flux reduction, which greatly hinders the applications of PP membranes. Dielectric barrier discharge (DBD) is an effective technique for surface modification of materials because it generates a large area of low-temperature plasma at atmospheric pressure. In this study, O₂ was added to nanosecond pulsed Ar DBD to increase its reactivity. Electrical and optical diagnostic techniques were used to study the discharge characteristics of the DBD at varying O₂ contents. The uniformity of the discharge was quantitatively analyzed using the observed discharge images. Water contact angle measurements were used to assess the surface hydrophilicity of polypropylene. The surface morphology and chemical composition of the PP materials before and after treatment were analyzed using field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The results show that the moderate addition of O₂ enhances surface hydrophilicity and the uniformity of the modification. By increasing the O₂ addition from 0% to 0.1%, the average power increased from 4.19 W to 5.79 W, and the energy efficiency increased from 17.78% to 21.51%. The water contact angle of the DBD-treated PP showed a tendency to decrease and then increase with increasing O₂ content, with the optimum O₂ addition determined to be 0.1%. Under this condition, the water contact angle of the PP surface decreased by 31.88°, which is 52.31% lower than the untreated surface. O₂ increases the number of oxygen-containing polar groups (-OH, C=O, and O-C=O) on the surface of the material, and deepens and densifies the grooves on the surface of the PP material, resulting in an increase in the hydrophilicity of the PP surface. Full article

(This article belongs to the Special Issue Advances in Design and Characterization of Graded and Hierarchical Honeycomb Materials)

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15 pages, 3877 KiB

Open AccessEditor’s ChoiceArticle

Unveiling the Influence of Hot Carriers on Photovoltage Formation in Perovskite Solar Cells

by Muhammad Mujahid, Aurimas Čerškus, Jonas Gradauskas, Asta Grigucevičienė, Raimondas Giraitis, Konstantinas Leinartas, Andžej Lučun, Kazimieras Petrauskas, Algirdas Selskis, Algirdas Sužiedėlis, Aldis Šilėnas, Edmundas Širmulis and Steponas Ašmontas

Materials 2025, 18(1), 85; https://doi.org/10.3390/ma18010085 - 28 Dec 2024

Viewed by 690

Abstract

The experimental and theoretical study of photovoltage formation in perovskite solar cells under pulsed laser excitation at 0.53 μm wavelength is presented. Two types of solar cells were fabricated on the base of cesium-containing triple cation perovskite films: (1) Cs_x(FA_0.83 [...] Read more.

The experimental and theoretical study of photovoltage formation in perovskite solar cells under pulsed laser excitation at 0.53 μm wavelength is presented. Two types of solar cells were fabricated on the base of cesium-containing triple cation perovskite films: (1) Cs_x(FA_0.83MA_0.17)_(1−x)Pb(I_0.83Br_0.17)₃ and (2) Cs_x(FA_0.83MA_0.17)_(1−x)Pb_0.8Sn_0.2(I_0.83Br_0.17)₃. It is found that photovoltage across the solar cells consists of two components, U = U_ph + U_f. The first one, U_ph, is the traditional photovoltage arising due to laser radiation-induced electron-hole pair generation. The second one, U_f, is the fast component following the laser pulse and has a polarity opposite to that of U_ph. It is shown that the fast photovoltage component results from the laser radiation-caused heating of free carriers. The transient photovoltage measurements show that the values of the fast component U_f are nearly the same in both types of perovskite solar cells. The magnitude of the traditional photovoltage of mixed Pb-Sn perovskite solar cells is lower than that of Pb-based cells. Full article

(This article belongs to the Special Issue Advances in Photoelectric Materials: Preparation, Properties, and Applications)

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26 pages, 14474 KiB

Open AccessEditor’s ChoiceArticle

Development of a Stable Process for Wire Embedding in Fused Filament Fabrication Printing Using a Geometric Correction Model

by Valentin Wilhelm Mauersberger, Fabian Ziervogel, Linda Weisheit, Lukas Boxberger and Welf-Guntram Drossel

Materials 2025, 18(1), 41; https://doi.org/10.3390/ma18010041 - 26 Dec 2024

Viewed by 532

Abstract

Using a newly developed tool head with an additional rotational axis and a wire feed, wires can be directly processed in the fused filament fabrication (FFF) process. Thus, electrical structures such as conductive paths, coils, heating elements, or sensors can be integrated into [...] Read more.

Using a newly developed tool head with an additional rotational axis and a wire feed, wires can be directly processed in the fused filament fabrication (FFF) process. Thus, electrical structures such as conductive paths, coils, heating elements, or sensors can be integrated into polymer parts. However, the accuracy of the wire deposition in curved sections of the print track is insufficient. To improve the wire position, a geometric correction model was set up, converted into G-code, and validated using test prints for different wire parameters. For this, a sample of printed arcs was evaluated regarding wire position and embedding quality using various visual methods. This also determined the optimal cooling time for the model. The process parameters extrusion coefficient and feed were then varied to identify optimal process parameters for a stable and at the same time efficient process. By varying the wire (copper, constantan) and polymer material (PLA, PETG), the model was checked for general validity. It was found that the position of the ø 0.2 mm wire can be improved with the correction model. Different sets of parameters can be found that enable good quality of embedding and wire position. Full article

(This article belongs to the Special Issue Current and Future Trends in Additive Manufacturing)

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15 pages, 11668 KiB

Open AccessEditor’s ChoiceArticle

Analysis of the Properties of Anticorrosion Systems Used for Structural Component Protection in Truck Trailers

by Wojciech Skotnicki and Dariusz Jędrzejczyk

Materials 2024, 17(24), 6303; https://doi.org/10.3390/ma17246303 - 23 Dec 2024

Viewed by 650

Abstract

The article compares the properties of coatings (cataphoretic, hot-dip zinc, and thermo-diffusion zinc) applied to steel components used in the automotive industry. The research focused on the analysis of corrosion resistance, hardness measurements, and tribological properties conducted on steel guides used in trailer [...] Read more.

The article compares the properties of coatings (cataphoretic, hot-dip zinc, and thermo-diffusion zinc) applied to steel components used in the automotive industry. The research focused on the analysis of corrosion resistance, hardness measurements, and tribological properties conducted on steel guides used in trailer and truck body structures as well as fasteners (M12 × 40 bolts). The base surfaces were cleaned chemically. Corrosion resistance was tested in a salt chamber, while coating thickness was measured using the magnetic induction method. Coating hardness (HV 0.02) was assessed with a microhardness tester, and tribological properties were tested under dry friction conditions. The results showed that the zinc coatings demonstrated corrosion resistance far superior to paint coatings. Full article

(This article belongs to the Special Issue Metal Coatings for Wear and Corrosion Applications (Second Edition))

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19 pages, 8834 KiB

Open AccessEditor’s ChoiceArticle

Protective Properties of Silane Composite Coatings Modified with Poly(3,4-ethylenedioxythiophene) with Heteropolyacid on X20Cr13 and 41Cr4 Steel

by Aleksandra Kucharczyk-Kotlewska, Lidia Adamczyk, Krzysztof Miecznikowski and Agata Dudek

Materials 2024, 17(24), 6177; https://doi.org/10.3390/ma17246177 - 18 Dec 2024

Viewed by 486

Abstract

This paper describes the methodology of the preparation and analyses of the structure and anticorrosion properties of silane coatings modified with poly(3,4-ethylenedioxythiophene) (PEDOT) with phosphododecamolybdic acid (PMo₁₂). Protective coatings, consisting of vinyltrimethoxysilane (VTMS), PEDOT powder with PMo₁₂ admixture (at different [...] Read more.

This paper describes the methodology of the preparation and analyses of the structure and anticorrosion properties of silane coatings modified with poly(3,4-ethylenedioxythiophene) (PEDOT) with phosphododecamolybdic acid (PMo₁₂). Protective coatings, consisting of vinyltrimethoxysilane (VTMS), PEDOT powder with PMo₁₂ admixture (at different concentrations), and ethanol, were deposited on X20Cr13 and 41Cr4 steels by immersion. The physicochemical properties of these silane coatings (e.g., surface morphology, thickness, roughness, and adhesion to the substrate) were elucidated using a digital microscope, a Fourier transform infrared spectrophotometer with attenuated total reflectance, and various electrochemical diagnostic techniques. Protective properties were assessed in acidified sulfate solutions with and without chloride ions (pH 2). Experimental results have shown that this coating displayed the effective protection of steel against general and pitting corrosion, stabilized the corrosion potential in the passive state, and provided barrier protection. Full article

(This article belongs to the Special Issue Fabrication and Properties of Functional Coatings Under Extreme Conditions)

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14 pages, 3148 KiB

Open AccessEditor’s ChoiceArticle

Liquid Structure of Magnesium Aluminates

by Viviana Cristiglio, Irina Pozdnyakova, Aleksei Bytchkov, Gabriel J. Cuello, Sandro Jahn, Didier Zanghi, Séverine Brassamin, James W. E. Drewitt and Louis Hennet

Materials 2024, 17(24), 6173; https://doi.org/10.3390/ma17246173 - 17 Dec 2024

Viewed by 600

Abstract

Magnesium aluminates (MgO)_x(Al₂O₃)_1−x belong to a class of refractory materials with important applications in glass and glass–ceramic technologies. Typically, these materials are fabricated from high-temperature molten phases. However, due to the difficulties in making measurements [...] Read more.

Magnesium aluminates (MgO)_x(Al₂O₃)_1−x belong to a class of refractory materials with important applications in glass and glass–ceramic technologies. Typically, these materials are fabricated from high-temperature molten phases. However, due to the difficulties in making measurements at very high temperatures, information on liquid-state structure and properties is limited. In this work, we employed the method of aerodynamic levitation with CO₂ laser heating at large scale facilities to study the structure of liquid magnesium aluminates in the system (MgO)_x(Al₂O₃)_1−x, with x = 0.33, 0.5, and 0.75, using X-ray and neutron diffraction. We determined the structure factors and corresponding pair distribution functions, providing detailed information on the short-range structural order in the liquid state. The local structures were similar across the range of compositions studied, with average coordination numbers of

{\bar{n}}_{A l}^{O} \sim 4.5

and

{\bar{n}}_{M g}^{O} \sim 5.1

and interatomic distances of

r_{AlO} = 1.76 - 1.78 Å

and

r_{MgO} = 1.93 - 1.95 Å

. The results are in good agreement with previous molecular dynamics simulations. For the spinel endmember MgAl₂O₄ (x = 0.5), the average Mg-O and Al-O coordination numbers gave rise to conflicting values for the inversion coefficient χ, indicating that the structural formula used to describe the solid-state order-disorder transition is not applicable in the liquid state. Full article

(This article belongs to the Section Materials Physics)

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11 pages, 1686 KiB

Open AccessEditor’s ChoiceArticle

Theoretical Investigation of Single-Atom Catalysts for Hydrogen Evolution Reaction Based on Two-Dimensional Tetragonal Mo₃C₂

by Bo Xue, Qingfeng Zeng, Shuyin Yu and Kehe Su

Materials 2024, 17(24), 6134; https://doi.org/10.3390/ma17246134 - 15 Dec 2024

Cited by 1 | Viewed by 624

Abstract

Developing highly efficient and cost-competitive electrocatalysts for the hydrogen evolution reaction (HER), which can be applied to hydrogen production by water splitting, is of great significance in the future of the zero-carbon economy. Here, by means of first-principles calculations, we have scrutinized the [...] Read more.

Developing highly efficient and cost-competitive electrocatalysts for the hydrogen evolution reaction (HER), which can be applied to hydrogen production by water splitting, is of great significance in the future of the zero-carbon economy. Here, by means of first-principles calculations, we have scrutinized the HER catalytic capacity of single-atom catalysts (SACs) by embedding transition-metal atoms in the C and Mo vacancies of a tetragonal Mo₃C₂ slab, where the transition-metal atoms refer to Ti, V, Cr, Mn, Fe, Co, Ni and Cu. All the Mo₃C₂-based SACs exhibit excellent electrical conductivity, which is favorable to charge transfer during HER. An effective descriptor, Gibbs free energy difference (ΔG_H*) of hydrogen adsorption, is adopted to evaluate catalytic ability. Apart from SACs with Cr, Mn and Fe located at C vacancies, all the other SACs can act as excellent catalysts for HER. Full article

(This article belongs to the Special Issue Advances in Multicomponent Catalytic Materials)

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23 pages, 9728 KiB

Open AccessEditor’s ChoiceArticle

Investigation of the Photocatalytic Activity of Copper-Modified Commercial Titania (P25) in the Process of Carbon Dioxide Photoreduction

by Konrad Sebastian Sobczuk, Iwona Pełech, Daniel Sibera, Piotr Staciwa, Agnieszka Wanag, Ewa Ekiert, Joanna Kapica-Kozar, Katarzyna Ćmielewska, Ewelina Kusiak-Nejman, Antoni Waldemar Morawski and Urszula Narkiewicz

Materials 2024, 17(24), 6139; https://doi.org/10.3390/ma17246139 - 15 Dec 2024

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Abstract

The photocatalytic reduction of CO₂ to useful products is an area of active research because it shows a potential to be an efficient tool for mitigating climate change. This work investigated the modification of titania with copper(II) nitrate and its impact on [...] Read more.

The photocatalytic reduction of CO₂ to useful products is an area of active research because it shows a potential to be an efficient tool for mitigating climate change. This work investigated the modification of titania with copper(II) nitrate and its impact on improving the CO₂ reduction efficiency in a gas-phase batch photoreactor under UV–Vis irradiation. The investigated photocatalysts were prepared by treating P25-copper(II) nitrate suspensions (with various Cu²⁺ concentrations), alkalized with ammonia water, in a microwave-assisted solvothermal reactor. The titania-based photocatalysts were characterized by SEM, EDS, ICP-OES, XRD and UV-Vis/DR methods. Textural properties were measured by the low-temperature nitrogen adsorption/desorption studies at 77 K. P25 photocatalysts modified with copper(II) nitrate used in the process of carbon dioxide reduction allowed for a higher efficiency both for the photocatalytic reduction of CO₂ to CH₄ and for the photocatalytic water decomposition to hydrogen as compared to a reference. Similarly, modified samples showed significantly higher selectivity towards methane in the CO₂ conversion process than the unmodified sample (a change from 30% for a reference sample to 82% for the P25-R-Cu-0.1 sample after the 6 h process). It was found that smaller loadings of Cu are more beneficial for increasing the photocatalytic activity of a sample. Full article

(This article belongs to the Special Issue Advances in Photocatalyst Materials and Green Chemistry)

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14 pages, 2706 KiB

Open AccessEditor’s ChoiceArticle

Evolution of Chemical, Structural, and Mechanical Properties of Titanium Nitride Films with Different Thicknesses Fabricated Using Pulsed DC Magnetron Sputtering

by Wei Mao, Runze Qi, Jiali Wu, Zhe Zhang and Zhanshan Wang

Materials 2024, 17(24), 6067; https://doi.org/10.3390/ma17246067 - 12 Dec 2024

Viewed by 576

Abstract

Considering the application of titanium nitride (TiN) films as a release layer in producing Wolter-I X-ray telescope mirror shells by the electroformed nickel replication (ENR) technique, this research pays attention to the influence of nanometer-scale thickness variation in the microstructure and physical properties [...] Read more.

Considering the application of titanium nitride (TiN) films as a release layer in producing Wolter-I X-ray telescope mirror shells by the electroformed nickel replication (ENR) technique, this research pays attention to the influence of nanometer-scale thickness variation in the microstructure and physical properties of TiN films deposited by the pulsed direct current (DC) magnetron sputtering method. This topic has received limited attention in the existing literature. TiN films (9.8 nm to 42.9 nm) were fabricated to comprehensively analyze the evolution in microstructure, depth distribution of elements, surface morphology, and intrinsic stress. With increasing thickness, TiN transitioned from amorphous to (200) and (111)–(200) mixed-oriented crystallization, explaining inflection points in the increasing roughness curve. Elements (C, N, O, Si, and Ti) and chemical bond proportions (Ti-N, Ti-N-O, and Ti-O) varied with film depth, and the fitting of film density can be optimized according to these variations. Crystallite size increased with thickness, which led to a reduction in intrinsic stress. It is evident that as film thickness increases, TiN forms a stable crystal structure, thereby reducing intrinsic stress, but resulting in increased roughness. Considering the impact of changes in thin film thickness on physical properties such as roughness, crystallinity, and intrinsic stress, a TiN film with a thickness of approximately 25 nm is deemed suitable for application as a release layer. Full article

(This article belongs to the Special Issue Advances in Thin Films Materials: Properties, Characterization, Physical Vapor Deposition and Application)

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34 pages, 1503 KiB

Open AccessEditor’s ChoiceArticle

The Generalized Phase Rule, the Extended Definition of the Degree of Freedom, the Component Rule and the Seven Independent Non-Compositional State Variables: To the 150th Anniversary of the Phase Rule of Gibbs

by George Kaptay

Materials 2024, 17(24), 6048; https://doi.org/10.3390/ma17246048 - 10 Dec 2024

Viewed by 1130

Abstract

The phase rule of Gibbs is one of the basic equations in phase equilibria. Although it has been with us for 150 years, discussions, interpretations and extensions have been published. Here, the following new content is provided: (i). the choice of independent components [...] Read more.

The phase rule of Gibbs is one of the basic equations in phase equilibria. Although it has been with us for 150 years, discussions, interpretations and extensions have been published. Here, the following new content is provided: (i). the choice of independent components is discussed, and the component rule is introduced, (ii). independent state variables are divided into compositional and non-compositional ones, (iii). the generalized phase rule is derived replacing number two in the original phase rule by the number of independent non-compositional state variables introduced above, (iv). the degree of freedom is decreased by the number of compositional constraints in special points (azeotrope and congruent melting) of phase diagrams, (v). a rule is derived connecting the maximum number of coexisting phases with the dimensions of the phase diagram, (vi). examples show how to apply the phase rule to unary, binary and ternary phase diagrams and their sections, (vii). the same is extended with the discussion of calculable and not calculable phase fractions, (viii). it is shown that the current definition of the degree of freedom is not sufficient in the number of cases, (ix). the current definition of the degree of freedom is extended, (x). the application of the generalized phase rule is demonstrated when other non-compositional state variables are applied for nano-phase diagrams, and/or for phase diagrams under the influence of electric potential difference, external magnetic field, mechanical strain or the gravitational field. Full article

(This article belongs to the Section Materials Chemistry)

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15 pages, 2348 KiB

Open AccessEditor’s ChoiceArticle

Fine Tuning the Glass Transition Temperature and Crystallinity by Varying the Thiophene-Quinoxaline Copolymer Composition

by Xun Pan and Mats R. Andersson

Materials 2024, 17(24), 6031; https://doi.org/10.3390/ma17246031 - 10 Dec 2024

Viewed by 707

Abstract

In recent years, the design and synthesis of high-performing conjugated materials for the application in organic photovoltaics (OPVs) have achieved lab-scale devices with high power conversion efficiency. However, most of the high-performing materials are still synthesised using complex multistep procedures, resulting in high [...] Read more.

In recent years, the design and synthesis of high-performing conjugated materials for the application in organic photovoltaics (OPVs) have achieved lab-scale devices with high power conversion efficiency. However, most of the high-performing materials are still synthesised using complex multistep procedures, resulting in high cost. For the upscaling of OPVs, it is also important to focus on conjugated polymers that can be made via fewer simple synthetic steps. Therefore, an easily synthesised amorphous thiophene−quinoxaline donor polymer, TQ1, has attracted our attention. An analogue, TQ-EH that has the same polymer backbone as TQ1 but with short branched side-chains, was previously reported as a donor polymer with increased crystallinity. We have synthesised copolymers with varied ratios between octyloxy and branched (2-ethylhexyl)oxy-substituted quinoxaline units having the same polymer backbone, with the aim to control the aggregation/crystallisation behaviour of the resulting copolymers. The optical properties, glass transition temperatures and degree of crystallinity of the new copolymers were systematically examined in relation to their copolymer composition, revealing that the composition can be used to fine-tune these properties of conjugated polymers. In addition, multiple sub-T_g transitions were found from some of the polymers, which are not commonly or clearly seen in other conjugated polymers. The new copolymers were tested in photovoltaic devices with a fullerene derivative as the acceptor, achieving slightly higher performances compared to the homopolymers. This work demonstrates that side-chain modification by copolymerisation can fine-tune the properties of conjugated polymers without requiring complex organic synthesis, thereby expanding the number of easily synthesised polymers for future upscaling of OPVs. Full article

(This article belongs to the Special Issue Advanced Photovoltaic Materials: Synthesis, Properties and Applications)

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30 pages, 7774 KiB

Open AccessEditor’s ChoiceReview

Perovskite in Triboelectric Nanogenerator and the Hybrid Energy Collection System

by Tong Wu, Zequan Zhao, Yin Lu, Hanzhang Yang, Xiaoning Liu, Xia Cao and Ning Wang

Materials 2024, 17(23), 6019; https://doi.org/10.3390/ma17236019 - 9 Dec 2024

Viewed by 1030

Abstract

In the context of escalating energy demands and environmental sustainability, the paradigm of global energy systems is undergoing a transformative shift to innovative and reliable energy-harvesting techniques ranging from solar cells to triboelectric nanogenerators (TENGs) to hybrid energy systems, where a fever in [...] Read more.

In the context of escalating energy demands and environmental sustainability, the paradigm of global energy systems is undergoing a transformative shift to innovative and reliable energy-harvesting techniques ranging from solar cells to triboelectric nanogenerators (TENGs) to hybrid energy systems, where a fever in the study of perovskite materials has been set off due to the excellent optoelectronic properties and defect tolerance features. This review begins with the basic properties of perovskite materials and the fundamentals of TENGs, including their working principles and general developing strategy, then delves into the key role of perovskite materials in promoting TENG-based hybrid technologies in terms of energy conversion. While spotlighting the coupling of triboelectric–optoelectronic effects in harnessing energy from a variety of sources, thereby transcending the limitations inherent to single-source energy systems, this review pays special attention to the strategic incorporation of perovskite materials into TENGs and TENG-based energy converting systems, which heralds a new frontier in enhancing efficiency, stability, and adaptability. At the end, this review highlights the remaining challenges such as stability, efficiency, and functionality for applications in TENG-based energy-harvesting systems, aiming to provide a comprehensive overview of the current landscape and the prospective trajectory of the role of perovskite materials in TENG-based energy-harvesting technologies within the renewable energy sector. Full article

(This article belongs to the Special Issue Featured Papers and Reviews of Advanced Materials for Sensing, Energy Conversion and Storage)

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18 pages, 9431 KiB

Open AccessEditor’s ChoiceArticle

Enhanced Wear Resistance and Thermal Dissipation of Copper–Graphene Composite Coatings via Pulsed Electrodeposition for Circuit Breaker Applications

by Daniele Almonti, Daniel Salvi, Nadia Ucciardello and Silvia Vesco

Materials 2024, 17(23), 6017; https://doi.org/10.3390/ma17236017 - 9 Dec 2024

Viewed by 870

Abstract

Copper, though highly conductive, requires improved wear resistance and thermal dissipation in applications that involve continuous movement and current-induced vibrations, such as power breakers. Conventional solutions, such as copper–tungsten alloys or lubricant use, face limitations in durability, friction, or environmental impact. This study [...] Read more.

Copper, though highly conductive, requires improved wear resistance and thermal dissipation in applications that involve continuous movement and current-induced vibrations, such as power breakers. Conventional solutions, such as copper–tungsten alloys or lubricant use, face limitations in durability, friction, or environmental impact. This study explores the development of copper–graphene (Cu-GNPs) composite coatings using pulsed electrodeposition to enhance the tribological, thermal, and mechanical properties of circuit breaker components by adopting an industrially scalable technique. The influence of deposition bath temperature, duty cycle, and frequency on coating morphology, hardness, wear resistance, and heat dissipation was systematically evaluated using a 2³ full factorial design and an Analysis of Variance (ANOVA). The results revealed that optimized pulsed electrodeposition significantly improved coating performance: hardness increased by 76%, wear volume decreased by more than 99%, and friction coefficient stabilized at 0.2, reflecting effective graphene integration. The addition of graphene further improved thermal diffusivity by 19.5%, supporting superior heat dissipation. These findings suggest that pulsed copper–graphene composite coatings offer a promising alternative to traditional copper alloys, enhancing the lifespan and reliability of electronic components through improved wear resistance, lower friction, and superior heat transfer. Full article

(This article belongs to the Special Issue Advanced Coating Research for Metal Surface Protection)

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15 pages, 7639 KiB

Open AccessEditor’s ChoiceArticle

Superhydrophobic Surfaces as a Potential Skin Coating to Prevent Jellyfish Stings: Inhibition and Anti-Tentacle Adhesion in Nematocysts of Jellyfish Nemopilema nomurai

by Yichen Xie, Yuanyuan Sun, Rongfeng Li, Song Liu, Ronge Xing, Pengcheng Li and Huahua Yu

Materials 2024, 17(23), 5983; https://doi.org/10.3390/ma17235983 - 6 Dec 2024

Viewed by 774

Abstract

The development of skin-protective materials that prevent the adhesion of cnidarian nematocysts and enhance the mechanical strength of these materials is crucial for addressing the issue of jellyfish stings. This study aimed to construct superhydrophobic nanomaterials capable of creating a surface that inhibits [...] Read more.

The development of skin-protective materials that prevent the adhesion of cnidarian nematocysts and enhance the mechanical strength of these materials is crucial for addressing the issue of jellyfish stings. This study aimed to construct superhydrophobic nanomaterials capable of creating a surface that inhibits nematocyst adhesion, therefore preventing jellyfish stings. We investigated wettability and nematocyst adhesion on four different surfaces: gelatin, polydimethylsiloxane (PDMS), dodecyl trichlorosilane (DTS)-modified SiO₂, and perfluorooctane triethoxysilane (PFOTS)-modified TiO₂. Our findings revealed that an increase in hydrophobicity significantly inhibited nematocyst adhesion. Furthermore, DTS-modified sprayed SiO₂ and PFOTS-modified sprated TiO₂ were further enhanced with low-surface-energy substances—cellulose nanofibers (CNF) and chitin nanocrystals (ChNCs)—to improve both hydrophobicity and mechanical strength. After incorporating CNF and ChNCs, the surface of s-TiO₂-ChNCs exhibited a contact angle of 153.49° even after undergoing abrasion and impact tests, and it maintained its hydrophobic properties with a contact angle of 115.21°. These results indicate that s-TiO₂-ChNCs can serve as an effective skin coating to resist tentacle friction. In conclusion, this study underscores the importance of utilizing hydrophobic skin materials to inhibit the adhesion of tentacle nematocysts, providing a novel perspective for protection against jellyfish stings. Full article

(This article belongs to the Special Issue Superhydrophobic Coating Materials: Preparation, Strategy and Application)

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9 pages, 4243 KiB

Open AccessEditor’s ChoiceArticle

Phase Evolution in Mn_1.6Zn_0.2Ni_0.6Mg_0.2Al_0.4O₄ High-Entropy Oxide Films by Heat Treatment

by Wei Ren, Xianhai Liu, Wenting Wu and Weili Wang

Materials 2024, 17(23), 5967; https://doi.org/10.3390/ma17235967 - 5 Dec 2024

Viewed by 554

Abstract

In this work, Mn-Zn-Ni-Mg-Al multi-layer films were annealed in air at different temperatures to form spinel-structured Mn_1.6Zn_0.2Ni_0.6Mg_0.2Al_0.4O₄ high-entropy oxide films. X-ray diffraction results demonstrate that the films possess a polycrystalline spinel phase [...] Read more.

In this work, Mn-Zn-Ni-Mg-Al multi-layer films were annealed in air at different temperatures to form spinel-structured Mn_1.6Zn_0.2Ni_0.6Mg_0.2Al_0.4O₄ high-entropy oxide films. X-ray diffraction results demonstrate that the films possess a polycrystalline spinel phase as well as impurity phases: when annealed at 650 °C and 750 °C, MnO₂ and Al₂O₃ impurity phases exist; at 950 °C, an Al₂O₃ impurity phase exists. Only at 850 °C does a pure spinel phase exist. However, the film at 750 °C exhibits the best conductive behavior, which indicates that the impurity phases may not have to be removed to maintain the best electrical properties of the film. Full article

(This article belongs to the Special Issue New Technique for Preparing Thin Film: Characteristic and Further Development)

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18 pages, 3164 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Bioactive Compounds from Banana Leaf Extracts: Influence of Extraction Methodologies and Their Integration into Knitted Hemp Fabrics

by Joana Mota Gomes, João Mariz, Catarina Rodrigues, Ana Luísa Alves, Joana Moreira, Bárbara Vieira, Rosa Maria Silva, Andrea Zille and Carla Joana Silva

Materials 2024, 17(23), 5884; https://doi.org/10.3390/ma17235884 - 30 Nov 2024

Viewed by 1339

Abstract

This study explores the bioactive potential of banana leaf extracts and their innovative integration into knitted hemp fabrics. To obtain the extracts, distinct extraction methodologies were employed, namely conventional extraction, ultrasound-assisted extraction, and pressurized-liquid extraction. Aqueous and hydroethanolic solvents, namely 20% (v [...] Read more.

This study explores the bioactive potential of banana leaf extracts and their innovative integration into knitted hemp fabrics. To obtain the extracts, distinct extraction methodologies were employed, namely conventional extraction, ultrasound-assisted extraction, and pressurized-liquid extraction. Aqueous and hydroethanolic solvents, namely 20% (v/v) and 50% (v/v), were employed during the extraction process. Furthermore, the cationization and functionalization of knitted hemp fabrics with the banana leaf extracts was achieved through padding. The extracts’ phenolic content and antioxidant activity were evaluated using the Folin–Ciocalteu (FC) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) assays, respectively. The results indicated that both ultrasound-assisted extraction and pressurized-assisted extraction substantially enhanced the yield of phenolic compounds in comparison to conventional extraction, while employing 50% EtOH as a solvent also improved extraction yields for all extraction methodologies. The functionalized knits were further characterized concerning their antioxidant activity by DPPH, assessing their antimicrobial properties through ATCC TM-100 standard against three microorganisms (Staphylococcus aureus, Candida Krusei, and Candida albicans), and UV protection according to the standard AS/NZS 4399:2017. Antioxidant activity was highest in knits functionalized with extracts obtained via ultrasound-assisted extraction, while antimicrobial properties were most pronounced in knits treated with hydroalcoholic extracts, particularly those derived from assisted methods. The UV protection was enhanced in extracts with higher ethanol concentrations obtained through ultrasound-assisted extraction, with these knits exhibiting the highest Ultraviolet Protection Factor (UPF). This research not only highlights the efficacy of the alternative extraction technologies but also offers valuable insights for the development of innovative, biocompatible materials with enhanced bioactive properties for diverse applications in the textile and healthcare sectors, paving the way for sustainable applications. Full article

(This article belongs to the Special Issue Leather, Textiles and Bio-Based Materials)

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14 pages, 5465 KiB

Open AccessEditor’s ChoiceArticle

Thin and Flexible PANI/PMMA/CNF Forest Films Produced via a Two-Step Floating Catalyst Chemical Vapor Deposition

by Foteini-Maria Papadopoulou, Spyros Soulis, Aikaterini-Flora A. Trompeta and Costas A. Charitidis

Materials 2024, 17(23), 5812; https://doi.org/10.3390/ma17235812 - 27 Nov 2024

Viewed by 882

Abstract

In this paper, we explore a straightforward two-step method to produce high-purity, vertically aligned multi-walled carbon nanofibres (MWCNFs) via chemical vapor deposition (CVD). Two distinct solutions are utilized for this CVD method: a catalytic solution consisting of ferrocene and acetonitrile (ACN) and a [...] Read more.

In this paper, we explore a straightforward two-step method to produce high-purity, vertically aligned multi-walled carbon nanofibres (MWCNFs) via chemical vapor deposition (CVD). Two distinct solutions are utilized for this CVD method: a catalytic solution consisting of ferrocene and acetonitrile (ACN) and a carbon source solution with camphor and ACN. The vapors of the catalytic solution inserted in the reaction chamber through external boiling result in a floating catalyst CVD approach that produces vertically aligned CNFs in a consistent manner. CNFs are grown in a conventional CVD horizontal reactor at 850 °C under atmospheric pressure and characterized by Raman spectroscopy, scanning and transmission electron microscopy (SEM and TEM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). Coating the MWCNTs with polymethyl methacrylate (PMMA) while still on the Si substrate retains the structure and results in a flexible, conductive thin film suitable for flexible electrodes. The film is 62 μm thick and stable in aqueous solutions, capable of withstanding further processing, such as electropolymerization with polyaniline, to be used for energy storage applications. Full article

(This article belongs to the Special Issue Emerging Technologies for Development of Novel Materials Systems and Coatings (Volume 2))

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18 pages, 4444 KiB

Open AccessEditor’s ChoiceArticle

Toward Sustainable 3D-Printed Sensor: Green Fabrication of CNT-Enhanced PLA Nanocomposite via Solution Casting

by Javid Sharifi, Ghaus Rizvi and Haniyeh (Ramona) Fayazfar

Materials 2024, 17(23), 5782; https://doi.org/10.3390/ma17235782 - 25 Nov 2024

Viewed by 873

Abstract

The current study explores, for the first time, an eco-friendly solution casting method using a green solvent, ethyl acetate, to prepare feedstock/filaments from polylactic acid (PLA) biopolymer reinforced with carbon nanotubes (CNTs), followed by 3D printing and surface activation for biosensing applications. Comprehensive [...] Read more.

The current study explores, for the first time, an eco-friendly solution casting method using a green solvent, ethyl acetate, to prepare feedstock/filaments from polylactic acid (PLA) biopolymer reinforced with carbon nanotubes (CNTs), followed by 3D printing and surface activation for biosensing applications. Comprehensive measurements of thermal, electrical, rheological, microstructural, and mechanical properties of developed feedstock and 3D-printed parts were performed and analyzed. Herein, adding 2 wt.% CNTs to the PLA matrix marked the electrical percolation, achieving conductivity of 8.3 × 10⁻³ S.m⁻¹, thanks to the uniform distribution of CNTs within the PLA matrix facilitated by the solution casting method. Rheological assessments paralleled these findings; the addition of 2 wt.% CNTs transitioned the nanocomposite from liquid-like to a solid-like behavior with a percolated network structure, significantly elevating rheological properties compared to the composite with 1 wt.% CNTs. Mechanical evaluations of the printed samples revealed improvement in tensile strength and modulus compared to virgin PLA by a uniform distribution of 2 wt.% CNTs into PLA, with an increase of 14.5% and 10.3%, respectively. To further enhance the electrical conductivity and sensing capabilities of the developed samples, an electrochemical surface activation treatment was applied to as-printed nanocomposite samples. The field-emission scanning electron microscopy (FE-SEM) analysis confirmed that this surface activation effectively exposed the CNTs to the surface of 3D-printed parts by removing a thin layer of polymer from the surface, thereby optimizing the composite’s electroconductivity performance. The findings of this study underscore the potential of the proposed eco-friendly method in developing advanced 3D-printed bio-nanocomposites based on carbon nanotubes and biopolymers, using a green solution casting and cost-effective material extrusion 3D-printing method, for electrochemical-sensing applications. Full article

(This article belongs to the Special Issue The Application of Materials in Modern Manufacturing Processes: Design, Performance and Applied Research)

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14 pages, 11006 KiB

Open AccessEditor’s ChoiceArticle

The Influence of the Steam Sterilization Process on Selected Properties of Polymer Samples Produced in MEX and JMT Processes

by Małgorzata Zaborniak, Janusz Kluczyński, Jakub Stańko and Tomasz Ślęzak

Materials 2024, 17(23), 5763; https://doi.org/10.3390/ma17235763 - 25 Nov 2024

Viewed by 789

Abstract

Polymeric materials are widely used in medical engineering, and with the dynamic development of additive manufacturing (AM) technology, increasing attention is being paid to research on the mechanical strength of composite polymer structures. At the same time, the impact of sterilization on, for [...] Read more.

Polymeric materials are widely used in medical engineering, and with the dynamic development of additive manufacturing (AM) technology, increasing attention is being paid to research on the mechanical strength of composite polymer structures. At the same time, the impact of sterilization on, for example, surgical templates and the influence of the sterilization process on the geometry of these parts have not been sufficiently studied. In this work, the effect of steam sterilization on samples made of polymer materials for medical applications was presented. This research was carried out on samples with normative geometry made of polyetheretherketone (PEEK) polymers produced using the Material Extrusion (MEX) AM process and acrylic formulation (MED610) produced by Jetting Modeling Technology (JMT). These materials provide biocompatibility, which makes them suitable for potential medical applications. Steam sterilization was performed in an autoclave at temperatures of 121 °C and 134 °C. The three-point bending strength properties were determined according to ISO 178 standards. An INSTRON 5967 strength testing machine was used for those tests. Surface roughness analysis (according to ISO 21920) was performed and presented in 2D and 3D surface views using the Mountains Map Software (version 6.0). Full article

(This article belongs to the Section Manufacturing Processes and Systems)

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15 pages, 7876 KiB

Open AccessEditor’s ChoiceArticle

Gas-Sensing Properties of Co₉S₈ Films Toward Formaldehyde, Ethanol, and Hydrogen Sulfide

by Myeong Gyu Kim and Yun-Hyuk Choi

Materials 2024, 17(23), 5743; https://doi.org/10.3390/ma17235743 - 24 Nov 2024

Viewed by 755

Abstract

The chemiresistive gas-sensing properties of pristine Co₉S₈ film are little known despite its potential as a promising gas sensor material due to its intrinsic characteristics. In this study, a pristine polycrystalline Co₉S₈ film (approximately 440 nm in [...] Read more.

The chemiresistive gas-sensing properties of pristine Co₉S₈ film are little known despite its potential as a promising gas sensor material due to its intrinsic characteristics. In this study, a pristine polycrystalline Co₉S₈ film (approximately 440 nm in thickness) is fabricated by depositing a Co₃O₄ film followed by sulfidation to investigate its gas-sensing properties. The prepared Co₉S₈ film sensor is found to exhibit high responsiveness towards formaldehyde (HCHO), ethanol (C₂H₅OH), and hydrogen sulfide (H₂S) at operating temperatures of 300 °C and 400 °C, with strong concentration dependence. On the other hand, the sensor shows very low or no responsiveness towards hydrogen (H₂), acetone (CH₃COCH₃), and nitrogen dioxide (NO₂). These results enhance our understanding of the intrinsic gas-sensing properties of Co₉S₈, aiding in the design and fabrication of high-performance chemiresistive gas sensors based on Co₉S₈. Full article

(This article belongs to the Section Materials Chemistry)

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18 pages, 4439 KiB

Open AccessEditor’s ChoiceArticle

The Influence of Horsetail (Equisetum arvense L.) Powder and Horsetail-Based Silica on the Crystallization Kinetics of Polylactide

by Olga Mysiukiewicz, Joanna Szulc and Andrzej Miklaszewski

Materials 2024, 17(23), 5697; https://doi.org/10.3390/ma17235697 - 21 Nov 2024

Viewed by 764

Abstract

Biogenic silica (SiO₂) sourced from living organisms, especially plants such as rice and other cereals, has recently been successfully applied in different polymeric compositions. Another rich source of biogenic silica is common horsetail (Equisetum arvense L.), containing up to 25% [...] Read more.

Biogenic silica (SiO₂) sourced from living organisms, especially plants such as rice and other cereals, has recently been successfully applied in different polymeric compositions. Another rich source of biogenic silica is common horsetail (Equisetum arvense L.), containing up to 25% SiO₂ in the dry matter. In this study, biogenic silica was obtained from horsetail powder by acid leaching in sulfuric acid and calcination at 400 °C. The analysis, including measurements of specific surface area using the Brunauer–Emmett–Teller method, assessment of crystallinity by X-ray diffraction, as well as chemical content analysis by Fourier-transform infrared spectroscopy showed that high-purity, high-surface mesoporous silica was obtained. The biogenic silica and horsetail powders were also introduced to polylactide (PLA) to determine their influence on the polymer’s crystallization, which was studied in both non-isothermal and isothermal conditions by differential scanning calorimetry. The crystallization parameters were calculated according to the Avrami method based on isothermal crystallization curves at 100, 110 and 120 °C. The crystalline structures were observed by optical microscopy in polarized light. It was found that both fillers improve the crystallization of PLA, especially in low-supercooling conditions, so they can be successfully utilized in industrial applications, when high crystallinity of polylactide is needed. Full article

(This article belongs to the Special Issue Advanced Designs of Materials, Machines and Processes in a Circular Economy)

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11 pages, 3705 KiB

Open AccessEditor’s ChoiceArticle

Zirconium Oxide as a Novel Material for Post-Endodontically Treated Teeth: Comparative Fracture Behavior of 3D-Printed Cobalt–Chromium, Milled Zirconium Oxide, and Quartz Fiber Posts

by Armin Sokolowski, Fernando Gustavo Warchomicka, Lukas Seebacher, Bernhard Remschmidt, Marcus Rieder, Lumnije Kqiku-Biblekaj and Alwin Sokolowski

Materials 2024, 17(22), 5611; https://doi.org/10.3390/ma17225611 - 17 Nov 2024

Viewed by 1105

Abstract

This study evaluates the mechanical properties of materials used in the post-endodontic restoration of root-treated teeth and examines their performance under stress to provide insights for material selection in clinical applications. Particular attention is given to zirconium oxide, which demonstrates promising characteristics due [...] Read more.

This study evaluates the mechanical properties of materials used in the post-endodontic restoration of root-treated teeth and examines their performance under stress to provide insights for material selection in clinical applications. Particular attention is given to zirconium oxide, which demonstrates promising characteristics due to its esthetic color and favorable material properties, positioning it as a potential material for future use in post-endodontic treatments. Three materials—prefabricated quartz fiber-reinforced composite, milled zirconium oxide, and additively manufactured cobalt–chromium—were evaluated using compressive-deflection tests. The specimens were subjected to a 45° compressive load extending 5 mm from a metal core. Their mechanical properties were analyzed using one-way ANOVA and Tukey’s post hoc test. Significant differences were observed among the materials. Quartz fiber posts, with the lowest force resistance, buckled at lower loads (143.3 ± 9.9 N), while zirconia posts failed in a brittle manner at higher forces (246.1 ± 97.2 N). Cobalt–chromium posts demonstrated the highest maximal force (323.2 ± 10.5 N, p < 0.001) and, unlike the other materials, bent rather than fractured. The failure patterns of the tested materials underscore the importance of careful material selection when restoring root-treated teeth. Despite displaying distinct fracture characteristics, zirconium oxide, due to its color, rigidity, and hardness, stands out as a promising material for future dental applications. Further research through randomized clinical trials is recommended to refine treatment approaches and optimize clinical outcomes. Full article

(This article belongs to the Special Issue Recent Research in Restorative Dental Materials)

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18 pages, 5642 KiB

Open AccessEditor’s ChoiceArticle

A New Slicer-Based Method to Generate Infill Inspired by Sandwich-Patterns for Reduced Material Consumption

by Patrick Steck, Dominik Schuler, Christian Witzgall and Sandro Wartzack

Materials 2024, 17(22), 5596; https://doi.org/10.3390/ma17225596 - 15 Nov 2024

Viewed by 824

Abstract

This work presents a novel infill method for additive manufacturing, specifically designed to optimize material use and enhance stiffness in fused filament fabrication (FFF) parts through a geometry-aware, corrugated design inspired by sandwich structures. Unlike standard infill patterns, which typically employ uniform, space-filling [...] Read more.

This work presents a novel infill method for additive manufacturing, specifically designed to optimize material use and enhance stiffness in fused filament fabrication (FFF) parts through a geometry-aware, corrugated design inspired by sandwich structures. Unlike standard infill patterns, which typically employ uniform, space-filling grids that often disregard load-specific requirements, this method generates a cavity inside the component to be printed and fill the space between inner and outer contours with continuous, adaptable extrusion paths. This design enables consistent support and improved load distribution, making it particularly effective for parts under bending stresses, as it enhances structural resilience without requiring additional material. Simulations performed on a 10 cm³ test part using this method showed potential reductions in material consumption by up to 77% and a decrease in print time by 78%, while maintaining stiffness comparable to parts using conventional 100% grid infill. Additionally, simulations demonstrated that the new corrugated infill pattern provides near-isotropic stiffness, addressing the anisotropic limitations often seen in traditional infill designs that are sensitive to load orientation. This geometry-aware infill strategy thus contributes to balanced stiffness across complex geometries, enhancing reliability under mechanical loads. By integrating directly with slicer software, this approach simplifies advanced stiffness optimization without the necessity of finite element analysis-based topology optimization. Full article

(This article belongs to the Special Issue Advanced Additive Manufacturing and Application)

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16 pages, 2999 KiB

Open AccessEditor’s ChoiceArticle

Modification of Poly(3-Hydroxybutyrate) with a Linear Polyurethane Modifier and Organic Nanofiller—Preparation and Structure–Property Relationship

by Iwona Zarzyka, Beata Krzykowska, Karol Hęclik, Wiesław Frącz, Grzegorz Janowski, Łukasz Bąk, Tomasz Klepka, Jarosław Bieniaś, Monika Ostapiuk, Aneta Tor-Świątek, Magda Droździel-Jurkiewicz, Adam Tomczyk, Anna Falkowska and Michał Kuciej

Materials 2024, 17(22), 5542; https://doi.org/10.3390/ma17225542 - 13 Nov 2024

Viewed by 809

Abstract

The growing demand for products made of polymeric materials, including the commonly used polypropylene (PP), is accompanied by the problem of storing and disposing of non-biodegradable waste, increasing greenhouse gas emissions, climate change and the creation of toxic products that constitute a health [...] Read more.

The growing demand for products made of polymeric materials, including the commonly used polypropylene (PP), is accompanied by the problem of storing and disposing of non-biodegradable waste, increasing greenhouse gas emissions, climate change and the creation of toxic products that constitute a health hazard of all living organisms. Moreover, most of the synthetic polymers used are made from petrochemical feedstocks from non-renewable resources. The use of petrochemical raw materials also causes degradation of the natural environment. A potential solution to these problems is the use of biopolymers. Biopolymers include biodegradable or biosynthesizable polymers, i.e., obtained from renewable sources or produced synthetically but from raw materials of natural origin. One of them is the poly(3-hydroxybutyrate) (P3HB) biopolymer, whose properties are comparable to PP. Unfortunately, it is necessary to modify its properties to improve its processing and operational properties. In the work, hybrid polymer nanobiocomposites based on P3HB, with the addition of chain, uncross-linked polyurethane (PU) and layered aluminosilicate modified with organic salts (Cloisite^®30B) were produced by extrusion process. The introduction of PU and Cloisite^®30B to the polymer matrix (P3HB) influenced the processing parameters beneficially and resulted in a decrease in the extrusion temperature of more than 10 °C. The influence of the simultaneous addition of a constant amount of PU (10 m/m%) and the different amounts of nanoadditives (1, 2 and 3 m/m%) on the compatibility, morphology and static mechanical properties of the resulted nanobiocomposites were examined. The component interactions by Fourier transformation infrared spectroscopy (FTIR) analysis, nano- and microscale structure studies using small-angle X-ray scattering (SAXS) and morphology by scanning electron microscopy (SEM) were carried out, and the hardness and tensile strength of the obtained polymer nanobiocomposites were determined. FTIR analysis identified the compatibility of the polyester matrix, PU, and organomodified montmorillonite, the greatest being 3 m/m% Cloisite30B content. The addition of PU to the polyester elasticizes the material and decreases the material’s strength and ductility. The presence of nanoclay enhanced the mechanical properties of nanobiocomposites. The resulting nanobiocomposites can be used in the production of short-life materials applied in gardening or agriculture. Full article

(This article belongs to the Special Issue Progressive Technologies and Materials in Mechanical and Materials Engineering)

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26 pages, 16106 KiB

Open AccessEditor’s ChoiceArticle

Physicochemical Characterization and Kinetics Study of Polymer Carriers with Vitamin C for Controlled Release Applications

by Magdalena Bańkosz

Materials 2024, 17(22), 5502; https://doi.org/10.3390/ma17225502 - 12 Nov 2024

Viewed by 878

Abstract

This study focuses on the selection and evaluation of a kinetic model for the release of vitamin C from different delivery systems, including microcapsules, hydrogels, and a hybrid system combining both. The microcapsules were synthesized from a 2% sodium alginate solution and with [...] Read more.

This study focuses on the selection and evaluation of a kinetic model for the release of vitamin C from different delivery systems, including microcapsules, hydrogels, and a hybrid system combining both. The microcapsules were synthesized from a 2% sodium alginate solution and with vitamin C incorporated in selected formulations. Hydrogels were obtained through photopolymerization using poly(ethylene glycol) diacrylate and polyvinyl alcohol, with and without the addition of vitamin C. The hybrid system incorporated the vitamin C-containing microcapsules within the hydrogel matrix. Physicochemical properties, such as density, porosity, and water vapor transmission rate (WVTR), were evaluated. Kinetic studies of vitamin C release were conducted under dynamic and static conditions, and the experimental data were fitted to six different kinetic models: zero-order, first-order, second-order, Higuchi, Korsmeyer–Peppas, and Hixson–Crowell. The Higuchi and Korsmeyer–Peppas models provided the best fit for most systems, indicating that the release is predominantly controlled by diffusion and, in dynamic conditions, swelling of the matrix. The hybrid system, while exhibiting slower release than the microcapsules and hydrogel alone, demonstrated more controlled and sustained release, which is advantageous for applications requiring prolonged action. Full article

(This article belongs to the Special Issue Research of Organic Molecules and Materials for Biological Application)

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39 pages, 8550 KiB

Open AccessEditor’s ChoiceReview

Enhancement of Magnetic Shielding Based on Low-Noise Materials, Magnetization Control, and Active Compensation: A Review

by Yijin Liu, Jianzhi Yang, Fuzhi Cao, Xu Zhang and Shiqiang Zheng

Materials 2024, 17(22), 5469; https://doi.org/10.3390/ma17225469 - 8 Nov 2024

Cited by 3 | Viewed by 2221

Abstract

Magnetic-shielding technologies play a crucial role in the field of ultra-sensitive physical measurement, medical imaging, quantum sensing, etc. With the increasing demand for the accuracy of magnetic measurement, the performance requirements of magnetic-shielding devices are also higher, such as the extremely weak magnetic [...] Read more.

Magnetic-shielding technologies play a crucial role in the field of ultra-sensitive physical measurement, medical imaging, quantum sensing, etc. With the increasing demand for the accuracy of magnetic measurement, the performance requirements of magnetic-shielding devices are also higher, such as the extremely weak magnetic field, gradient, and low-frequency noise. However, the conventional method to improve the shielding performance by adding layers of materials is restricted by complex construction and inherent materials noise. This paper provides a comprehensive review about the enhancement of magnetic shielding in three aspects, including low-noise materials, magnetization control, and active compensation. The generation theorem and theoretical calculation of materials magnetic noise is summarized first, focusing on the development of spinel ferrites, amorphous, and nanocrystalline. Next, the principles and applications of two magnetization control methods, degaussing and magnetic shaking, are introduced. In the review of the active magnetic compensation system, the forward and inverse design methods of coil and the calculation method of the coupling effect under the ferromagnetic boundary of magnetic shield are explained in detail, and their applications, especially in magnetocardiography (MCG) and magnetoencephalogram (MEG), are also mainly described. In conclusion, the unresolved challenges of different enhancement methods in materials preparation, optimization of practical implementation, and future applications are proposed, which provide comprehensive and instructive references for corresponding research. Full article

(This article belongs to the Special Issue Preparation, Electromagnetic Absorption and Shielding Properties of Electromagnetic Functional Materials)

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22 pages, 3931 KiB

Open AccessEditor’s ChoiceReview

Securing Rare Earth Permanent Magnet Needs for Sustainable Energy Initiatives

by Dan-Cristian Popa and Loránd Szabó

Materials 2024, 17(22), 5442; https://doi.org/10.3390/ma17225442 - 7 Nov 2024

Viewed by 1480

Abstract

Rare earth permanent magnets are vital in various sectors, including renewable energy conversion, where they are widely used in permanent magnet generators. However, the global supply and availability of these materials present significant risks, and their mining and processing have raised serious environmental [...] Read more.

Rare earth permanent magnets are vital in various sectors, including renewable energy conversion, where they are widely used in permanent magnet generators. However, the global supply and availability of these materials present significant risks, and their mining and processing have raised serious environmental concerns. This paper reviews the necessary legislative, economic, and technological measures that must be implemented to address these issues. While it may not be feasible to eliminate the risks associated with the availability of rare earth materials, researchers in the field of electrical generators can play a crucial role in significantly reducing the demand for newly mined and processed such materials, thereby mitigating the negative environmental impacts of their extraction and production. Full article

(This article belongs to the Special Issue Advances in Sustainable Energy Materials and Devices)

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10 pages, 2301 KiB

Open AccessEditor’s ChoiceArticle

Fibrillated Films for Suspension Catalyst Immobilization—A Kinetic Study of the Nitrobenzene Hydrogenation

by Chiara Boscagli, Enrico Lepre, Oliver Hofmann, Lukas Wengeler, Marcel Schmitt, Ivana Jevtovikj, Carlos Lizandara-Pueyo and Stephan A. Schunk

Materials 2024, 17(22), 5411; https://doi.org/10.3390/ma17225411 - 6 Nov 2024

Viewed by 856

Abstract

The immobilization of suspension catalysts in flexible, fibrillated films offers a promising solution to the mass transfer limitations often encountered in three-phase hydrogenation reactions. This study investigates the catalytic performance and mass transfer properties of fibrillated films in the hydrogenation of nitrobenzene to [...] Read more.

The immobilization of suspension catalysts in flexible, fibrillated films offers a promising solution to the mass transfer limitations often encountered in three-phase hydrogenation reactions. This study investigates the catalytic performance and mass transfer properties of fibrillated films in the hydrogenation of nitrobenzene to aniline, comparing them to free-flowing powdered catalysts. Fibrillated films were prepared from Pd/C catalysts with varying thicknesses (100–400 µm), and their performance was evaluated through kinetic studies in both batch reactors and microreactors. The specific activity of the films was significantly influenced by film thickness with thinner films demonstrating lower mass transfer limitations. However, mass transfer limitations were observed in thicker films, prompting the development of alternative film designs, including enhanced macro-porous films and sandwich structures. These modifications successfully minimized diffusion limitations, achieving similar specific activity to the powder catalysts while maintaining the mechanical stability of the films. This work demonstrates the feasibility of using fibrillated films for continuous catalytic processes and highlights their potential for efficient catalyst reuse, avoiding filtration steps and enhancing process sustainability. Furthermore, while PTFE remains indispensable for producing such films due to its mechanical and thermal stability, ongoing research focuses on identifying more environmentally friendly alternatives without compromising performance. Full article

(This article belongs to the Special Issue Recent Developments in Catalytic Materials)

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21 pages, 1766 KiB

Open AccessEditor’s ChoiceReview

Advanced Biomaterials for Lacrimal Tissue Engineering: A Review

by Kevin Y. Wu, Archan Dave, Patrick Daigle and Simon D. Tran

Materials 2024, 17(22), 5425; https://doi.org/10.3390/ma17225425 - 6 Nov 2024

Cited by 1 | Viewed by 1282

Abstract

The lacrimal gland (LG) is vital for ocular health, producing tears that lubricate and protect the eye. Dysfunction of the LG leads to aqueous-deficient dry eye disease (DED), significantly impacting quality of life. Current treatments mainly address symptoms rather than the underlying LG [...] Read more.

The lacrimal gland (LG) is vital for ocular health, producing tears that lubricate and protect the eye. Dysfunction of the LG leads to aqueous-deficient dry eye disease (DED), significantly impacting quality of life. Current treatments mainly address symptoms rather than the underlying LG dysfunction, highlighting the need for regenerative therapies. Tissue engineering offers a promising solution, with biomaterials playing crucial roles in scaffolding and supporting cell growth for LG regeneration. This review focuses on recent advances in biomaterials used for tissue engineering of the lacrimal gland. We discuss both natural and synthetic biomaterials that mimic the extracellular matrix and provide structural support for cell proliferation and differentiation. Natural biomaterials, such as Matrigel, decellularized extracellular matrices, chitosan, silk fibroin hydrogels, and human amniotic membrane are evaluated for their biocompatibility and ability to support lacrimal gland cells. Synthetic biomaterials, like polyethersulfone, polyesters, and biodegradable polymers (PLLA and PLGA), are assessed for their mechanical properties and potential to create scaffolds that replicate the complex architecture of the LG. We also explore the integration of growth factors and stem cells with these biomaterials to enhance tissue regeneration. Challenges such as achieving proper vascularization, innervation, and long-term functionality of engineered tissues are discussed. Advances in 3D bioprinting and scaffold fabrication techniques are highlighted as promising avenues to overcome current limitations. Full article

(This article belongs to the Section Biomaterials)

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18 pages, 3418 KiB

Open AccessEditor’s ChoiceArticle

On the Influence of Welding Parameters and Their Interdependence During Robotic Continuous Ultrasonic Welding of Carbon Fibre Reinforced Thermoplastics

by Filipp Köhler, Irene Fernandez Villegas, Clemens Dransfeld and Axel Herrmann

Materials 2024, 17(21), 5282; https://doi.org/10.3390/ma17215282 - 30 Oct 2024

Viewed by 896

Abstract

Ultrasonic welding of fibre-reinforced thermoplastics is a joining technology with high potential for short welding times and low energy consumption. While the majority of the current studies on continuous ultrasonic welding have so far focused on woven reinforcements, unidirectional materials are preferred for [...] Read more.

Ultrasonic welding of fibre-reinforced thermoplastics is a joining technology with high potential for short welding times and low energy consumption. While the majority of the current studies on continuous ultrasonic welding have so far focused on woven reinforcements, unidirectional materials are preferred for highly loaded aerospace components due to their better mechanical performance. Therefore, this paper investigates the influence and interdependence of the welding speed, amplitude, and energy director thickness on the weld quality of adherends made of unidirectional composites. The quality of the welded joints is assessed by a single-lap shear strength and fracture surface analysis complemented by the microscopic analysis of cross-sections and comparison to a co-consolidated reference. The results showed that the welding process is highly affected by changing welding speeds for a given amplitude. Furthermore, while lower amplitudes lead to significant scatter in the welding quality, higher amplitudes result in increased heating rates and a fully molten energy director even for high welding speeds. Nevertheless, insufficient consolidation at high welding speeds results in porosity in the weld line. Finally, it was observed that thicker, and therefore more compliant, energy directors lead to more uniform melting of the energy director and less deviation in the weld quality for a wider range of welding speeds. Full article

(This article belongs to the Special Issue Ultrasound for Material Characterization and Processing (3rd Edition))

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16 pages, 5871 KiB

Open AccessEditor’s ChoiceArticle

Effect of Natural Inhibitors on the Corrosion Properties of Grade 2 Titanium Alloy

by Mehrdad Faraji, Luca Pezzato, Arshad Yazdanpanah, Giacomo Nardi, Mojtaba Esmailzadeh and Irene Calliari

Materials 2024, 17(21), 5202; https://doi.org/10.3390/ma17215202 - 25 Oct 2024

Cited by 2 | Viewed by 878

Abstract

This study investigates the effects of natural inhibitors (pomegranate, algae, and tomato extracts) on the corrosion resistance of titanium (grade 2). To deepen understanding the inhibition mechanism, Molecular Dynamic (MD) and Monte Carlo (MC) simulations were employed to analyze adsorption behaviors and identify [...] Read more.

This study investigates the effects of natural inhibitors (pomegranate, algae, and tomato extracts) on the corrosion resistance of titanium (grade 2). To deepen understanding the inhibition mechanism, Molecular Dynamic (MD) and Monte Carlo (MC) simulations were employed to analyze adsorption behaviors and identify optimal adsorption sites on titanium oxide (TiO₂) surfaces for compounds within the inhibitors. Results indicate non-flat adsorption orientations, with pomegranate peel extract components showing superior inhibition capabilities, attributed to the formation of strong O-H chemical bonds with the TiO₂ surface. In the experimental part of the study Electrochemical Impedance Spectroscopy (EIS) and Potentiodynamic Polarization (PDP) were conducted. Two electrolytes were tested: a solution 3.5% NaCl and a solution 0.5 M NaOH. All the tests were performed with 5% of inhibitor and with the reference solution. Also, inhibition efficiency was calculated on the base of PDP tests. The study found that pomegranate extract can act as a good corrosion inhibitor for titanium alloy in aqueous solutions 0.5 M NaOH. This was demonstrated by the increase in the corrosion potential and impedance modulus and decrease in the corrosion current density after the addition of pomegranate extract to the solution. However, in a 3.5% NaCl solution, the efficacy of pomegranate extract was less pronounced, probably due to the high aggressivity of the electrolyte. Tomato and algae extract have instead shown very low inhibition effects in all the tested conditions. Full article

(This article belongs to the Special Issue Corrosion Behavior and Mechanical Properties of Metallic Materials)

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31 pages, 18671 KiB

Open AccessEditor’s ChoiceArticle

Effect of Artificial Saliva Modification on Corrosion Resistance of Metal Oxide Coatings on Co-Cr-Mo Dental Alloy

by Bożena Łosiewicz, Patrycja Osak, Karolina Górka-Kulikowska and Joanna Maszybrocka

Materials 2024, 17(21), 5166; https://doi.org/10.3390/ma17215166 - 23 Oct 2024

Cited by 1 | Viewed by 857

Abstract

Surface modifications not only improve the corrosion resistance of Co-Cr-Mo dental alloys (Bego Wirobond^® C) but also ensure their long-term performance and reliability in dental applications. This paper describes the preparation of single-layer TiO₂-ZrO₂ sol–gel coatings on the Co-Cr-Mo [...] Read more.

Surface modifications not only improve the corrosion resistance of Co-Cr-Mo dental alloys (Bego Wirobond^® C) but also ensure their long-term performance and reliability in dental applications. This paper describes the preparation of single-layer TiO₂-ZrO₂ sol–gel coatings on the Co-Cr-Mo dental alloy using the method of dip-coating. The TiO₂-ZrO₂ sol–gel coatings were sintered at 300 and 500 °C. SEM analysis shows that sintering at 300 °C produces a uniform, slightly dense structure without micro-cracks, while sintering at 500 °C results in a denser structure with micro-cracks due to higher stress and shrinkage. EDS confirms that sintering temperature affects the elemental composition of the coating, with higher temperatures causing the volatilization or diffusion of Ti and Zr. Roughness measurements indicate that the Ra value increases with the sintering temperature, meeting dental application requirements. Electrochemical measurements by open-circuit potential, EIS, and cyclic potentiodynamic curves demonstrate that sintering temperature and saliva composition affect corrosion resistance, with NaF and mouthwashes (Listerine Total Care Teeth Protection^® and Meridol^®) generally increasing charge transfer resistance and double-layer capacitance. The ceramic TiO₂-ZrO₂ coatings significantly reduce pitting corrosion susceptibility at physiological and acidic pH, with the 500 °C sintered coating showing better protective properties. These findings highlight the potential of TiO₂-ZrO₂ coatings in enhancing the performance of Co-Cr-Mo dental alloys. Full article

(This article belongs to the Special Issue Corrosion Behavior and Mechanical Properties of Metallic Materials)

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17 pages, 6110 KiB

Open AccessEditor’s ChoiceArticle

Definition, Fabrication, and Compression Testing of Sandwich Structures with Novel TPMS-Based Cores

by Alexandru Vasile, Dan Mihai Constantinescu, Iulian Constantin Coropețchi, Ștefan Sorohan and Dragoș Alexandru Apostol

Materials 2024, 17(21), 5150; https://doi.org/10.3390/ma17215150 - 22 Oct 2024

Cited by 2 | Viewed by 1067

Abstract

Triply periodic minimal surfaces (TPMSs) constitute a type of metamaterial, deriving their unique characteristics from their microstructure topology. They exhibit wide parameterization possibilities, but their behavior is hard to predict. This study focuses on using an implicit modeling method that can effectively generate [...] Read more.

Triply periodic minimal surfaces (TPMSs) constitute a type of metamaterial, deriving their unique characteristics from their microstructure topology. They exhibit wide parameterization possibilities, but their behavior is hard to predict. This study focuses on using an implicit modeling method that can effectively generate novel thin-walled metamaterials, proposing eight shell-based TPMS topologies and one stochastic structure, along with the gyroid acting as a reference. After insights into the printability and design parameters of the proposed samples are presented, a cell homogeneity analysis is conducted, indicating the level of anisotropy of each cellular structure. For each of the designed metamaterials, multiple samples were printed using a stereolithography (SLA) method, using a constant 0.3 relative density and 50 µm resolution. To provide an understanding of their behavior, compression tests of sandwich-type specimens were performed and specific deformation modes were identified. Furthermore, the study estimates the general mechanical behavior of the novel TPMS cores at different relative densities using an open cell mathematical model. Alterations of the uniform topologies are then suggested and the way these modifications affect the compressive response are presented. Thus, this paper demonstrates that an implicit modeling method could easily generate novel thin-walled TPMSs and stochastic structures, which led to identifying an artificially designed structure with superior properties to already mature topologies, such as the gyroid. Full article

(This article belongs to the Special Issue Advances in Metamaterials: Structure, Properties and Applications)

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20 pages, 12921 KiB

Open AccessEditor’s ChoiceArticle

Parameter Optimization for Laser Peen Forming on 6005A-T6 Aluminum Alloy Plates to Enhance the Constrained Deformation of Integral Stiffened Plates

by Gaoqiang Jiang, Jianzhong Zhou, Jian Wu, Shu Huang, Xiankai Meng and Yongxiang Hu

Materials 2024, 17(20), 5090; https://doi.org/10.3390/ma17205090 - 18 Oct 2024

Cited by 2 | Viewed by 710

Abstract

Multiscale parameter optimization for laser peen forming (LPF) on 6005A-T6 aluminum alloy plates was conducted through a combination of simulation and experimentation. By obtaining the optimal parameter, this study aims to explore the constrained deformation and forming laws of the integral stiffened plates. [...] Read more.

Multiscale parameter optimization for laser peen forming (LPF) on 6005A-T6 aluminum alloy plates was conducted through a combination of simulation and experimentation. By obtaining the optimal parameter, this study aims to explore the constrained deformation and forming laws of the integral stiffened plates. Detailed descriptions were provided regarding the dynamic response process and transient behavior of aluminum alloy plates under ultrahigh strain rates, along with an in-depth analysis of the stress evolution. The results reveal that laser beam diameter and laser beam energy can achieve large range forming, while the number of tracks facilitates the precise deformation adjustment. During the 12-track LPF process, there is an overall upward trend in deformation values accompanied by a dynamic increase in the bend curvature. After static relaxation, the deformation value recovers to 55.2% of the final bending curvature. The chord direction scanning of stiffened plates exhibits a larger bending curvature, indicating its greater forming capacity for large-sized single unfolding direction formation; whereas, the unfolding direction scanning of stiffened plates excels in achieving efficient integrated two-way forming. Full article

(This article belongs to the Special Issue Laser Processing of Metals and Alloys: Structures, Properties, and Applications)

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12 pages, 2780 KiB

Open AccessEditor’s ChoiceArticle

Fabrication and Characterization of Flexible CuI-Based Photodetectors on Mica Substrates by a Low-Temperature Solution Process

by Chien-Yie Tsay, Yun-Chi Chen, Hsuan-Meng Tsai and Kai-Hsiang Liao

Materials 2024, 17(20), 5011; https://doi.org/10.3390/ma17205011 - 14 Oct 2024

Viewed by 928

Abstract

Both CuI and CuI:Zn semiconductor thin films, along with MSM-structured UV photodetectors, were prepared on flexible mica substrates at low temperature (150 °C) by a wet chemical method. The two CuI-based films exhibited a polycrystalline phase with an optical bandgap energy close to [...] Read more.

Both CuI and CuI:Zn semiconductor thin films, along with MSM-structured UV photodetectors, were prepared on flexible mica substrates at low temperature (150 °C) by a wet chemical method. The two CuI-based films exhibited a polycrystalline phase with an optical bandgap energy close to 3.0 eV. Hall effect measurements indicated that the CuI thin film sample had p-type conductivity, while the CuI:Zn thin film sample exhibited n-type conductivity, with the latter showing a higher carrier mobility of 14.78 cm²/Vs compared to 7.67 cm²/Vs for the former. The I-V curves of both types of photodetectors showed asymmetric rectification characteristics with rectification ratios at ±3 V of 5.23 and 14.3 for the CuI and CuI:Zn devices, respectively. Flexible CuI:Zn devices exhibited significantly better sensitivity, responsivity, and specific detectivity than CuI devices both before and after static bending tests. It was found that, while the optoelectronic performance of flexible CuI-based photodetectors degraded under tensile stress during static bending tests, they still exhibited good reproducibility and repeatability in their photoresponses. Full article

(This article belongs to the Special Issue Current Research in Thin-Film Deposition: From Principles and Technologies to Film Properties and Applications)

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14 pages, 11311 KiB

Open AccessEditor’s ChoiceArticle

Effect of Cooling Rate on α Variant Selection and Microstructure Evolution in TB17 Titanium Alloy

by Guoqiang Shang, Xueping Gan, Xinnan Wang, Jinyang Ge, Chao Li, Zhishou Zhu, Xiaoyong Zhang and Kechao Zhou

Materials 2024, 17(20), 5010; https://doi.org/10.3390/ma17205010 - 13 Oct 2024

Cited by 2 | Viewed by 1381

Abstract

The α variant selection and microstructure evolution in a new metastable β titanium alloy TB17 were studied in depth by DTA, microhardness, XRD, SEM, and EBSD characterization methods. Under the rapid cooling rate conditions (150 °C/min–400 °C/min), only a very small amount of [...] Read more.

The α variant selection and microstructure evolution in a new metastable β titanium alloy TB17 were studied in depth by DTA, microhardness, XRD, SEM, and EBSD characterization methods. Under the rapid cooling rate conditions (150 °C/min–400 °C/min), only a very small amount of granular α_WM (α Widmanstatten precipitates within the grains) precipitated within the grains. The secondary α phase precipitated in the alloy changed from granular to fine needle-like at moderate cooling rates (15 °C/min–20 °C/min). When continuing to slow down the cooling rates (10 °C/min and 1 °C/min), the α_GB (α precipitates along the β grain boundaries), α_WGB (α Widmanstatten precipitates that developed from β grain boundaries or α_GB) and α_WM grew rapidly. Moreover, the continuous cooling transformation (CCT) diagram illustrated the effect of cooling rate on the β/α phase transition. EBSD analysis revealed that the variants selection of α near the original β grain boundary is mainly divided into three categories. (i) The double-BOR (Burgers orientation relationship) α_WGB colonies within neighboring β grains grow in different directions but have the same crystallographic orientation. (ii) The double-BOR α_WGB colonies within neighboring β grains have different growth directions and different crystallographic orientations. (iii) The double-BOR α_WGB colonies within the same grain have the same growth direction, but different crystallographic directions. And these double-BOR α_WGB colonies correspond to two variants of the given {0001}α//{110}β. Full article

(This article belongs to the Special Issue Research on Performance Improvement of Advanced Alloys)

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21 pages, 18454 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Image-Based Peridynamic Modeling-Based Micro-CT for Failure Simulation of Composites

by Zhuo Wang, Ling Zhang, Jiandong Zhong, Yichao Peng, Yi Ma and Fei Han

Materials 2024, 17(20), 4987; https://doi.org/10.3390/ma17204987 - 12 Oct 2024

Viewed by 1329

Abstract

By utilizing computed tomography (CT) technology, we can gain a comprehensive understanding of the specific details within the material. When combined with computational mechanics, this approach allows us to predict the structural response through numerical simulation, thereby avoiding the high experimental costs. In [...] Read more.

By utilizing computed tomography (CT) technology, we can gain a comprehensive understanding of the specific details within the material. When combined with computational mechanics, this approach allows us to predict the structural response through numerical simulation, thereby avoiding the high experimental costs. In this study, the tensile cracking behavior of carbon–silicon carbide (C/SiC) composites is numerically simulated using the bond-based peridynamics model (BB-PD), which is based on geometric models derived from segmented images of three-dimensional (3D) CT data. To obtain results efficiently and accurately, we adopted a deep learning-based image recognition model to identify the kinds of material and then the pixel type that corresponds to the material point, which can be modeled by BB-PD for failure simulation. The numerical simulations of the composites indicate that the proposed image-based peridynamics (IB-PD) model can accurately reconstruct the actual composite microstructure. It can effectively simulate various fracture phenomena such as interfacial debonding, crack propagation affected by defects, and damage to the matrix. Full article

(This article belongs to the Special Issue Alloys and Composites: Structural and Functional Applications, Second Edition)

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15 pages, 4643 KiB

Open AccessEditor’s ChoiceArticle

Composites Based on Electrodeposited WO₃ and TiO₂ Nanoparticles for Photoelectrochemical Water Splitting

by Ramunas Levinas, Elizabeth Podlaha, Natalia Tsyntsaru and Henrikas Cesiulis

Materials 2024, 17(19), 4914; https://doi.org/10.3390/ma17194914 - 8 Oct 2024

Viewed by 1170

Abstract

Photoelectrochemically active WO₃ films were fabricated by electrodeposition from an acidic (pH 2), hydrogen-peroxide-containing electrolyte at −0.5 V vs. SCE. WO₃-TiO₂ composites were then synthesized under the same conditions, but with 0.2 g/L of anatase TiO₂ nanoparticles (⌀ [...] Read more.

Photoelectrochemically active WO₃ films were fabricated by electrodeposition from an acidic (pH 2), hydrogen-peroxide-containing electrolyte at −0.5 V vs. SCE. WO₃-TiO₂ composites were then synthesized under the same conditions, but with 0.2 g/L of anatase TiO₂ nanoparticles (⌀ 36 nm), mechanically suspended in the solution by stirring. After synthesis, the films were annealed at 400 °C. Structural characterization by XRD showed that the WO₃ films exhibit the crystalline structure of a non-stoichiometric hydrate, whereas, in WO₃-TiO₂, the WO₃ phase was monoclinic. The oxidation of tungsten, as revealed by XPS, was W⁶⁺ for both materials. Ti was found to exist mainly as Ti⁴⁺ in the composite, with a weak Ti³⁺ signal. The efficiency of the WO₃ films and composites as an oxygen evolution reaction (OER) photo-electrocatalyst was examined. The composite would generate approximately three times larger steady-state photocurrents at 1.2 V vs. SCE in a neutral 0.5 M Na₂SO₄ electrolyte compared to WO₃ alone. The surface recombination of photogenerated electron–hole pairs was characterized by intensity-modulated photocurrent spectroscopy (IMPS). Photogenerated charge transfer efficiencies were calculated from the spectra, and at 1.2 V vs. SCE, were 86.6% for WO₃ and 62% for WO₃-TiO₂. Therefore, the composite films suffered from relatively more surface recombination but generated larger photocurrents, which resulted in overall improved photoactivity. Full article

(This article belongs to the Special Issue Electrochemical Material Science and Electrode Processes)

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26 pages, 9412 KiB

Open AccessEditor’s ChoiceArticle

Mechanisms of Chemically Promoted Material Removal Examined for Molybdenum and Copper CMP in Weakly Alkaline Citrate-Based Slurries

by K. U. Gamagedara and D. Roy

Materials 2024, 17(19), 4905; https://doi.org/10.3390/ma17194905 - 7 Oct 2024

Cited by 1 | Viewed by 1914

Abstract

Chemical mechanical planarization (CMP) of metal components is an essential step in the fabrication of integrated circuits. Metal CMP is a complex process where strategically activated (electro)chemical reactions serve to structurally weaken the surface layers of the material being processed, and the resulting [...] Read more.

Chemical mechanical planarization (CMP) of metal components is an essential step in the fabrication of integrated circuits. Metal CMP is a complex process where strategically activated (electro)chemical reactions serve to structurally weaken the surface layers of the material being processed, and the resulting overburdens are removed under low-force abrasion. Understanding the tribo-electrochemical mechanisms of this process is crucial to successfully designing the consumable materials for advanced CMP slurries that are needed for the new technology nodes. Using a model CMP system involving copper (wiring material in interconnect structures) and molybdenum (a new diffusion barrier material for copper), the present work illustrates a tribo-electroanalytical scheme for studying various mechanistic details of metal CMP. Electroanalytical probes are employed both in the absence and in the presence of surface polishing to quantify the interplay between mechanical abrasion and chemical surface modification. Weakly alkaline slurry formulations are tested with variable concentrations of silica abrasives and a complexing agent, citric acid. The results serve to examine the link between material removal and tribo-corrosion and to identify the functions of the active slurry additives in governing the rates and selectivity of material removal for CMP. Full article

(This article belongs to the Section Materials Chemistry)

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12 pages, 4941 KiB

Open AccessEditor’s ChoiceArticle

Self-Adaptive Intelligent Metasurface Cloak System with Integrated Sensing Units

by Panyi Li, Jiwei Zhao, Caofei Luo, Zhicheng Pei, Hui Jin, Yitian Huang, Wei Zhou and Bin Zheng

Materials 2024, 17(19), 4863; https://doi.org/10.3390/ma17194863 - 2 Oct 2024

Viewed by 3409

Abstract

Metasurfaces, which are ultrathin planar metamaterials arranged in certain global sequences, interact uniquely with the surrounding light field and exhibit unusual effects of light modulation. Many interesting applications have been discovered based on metasurfaces, particularly in invisibility cloaks. However, most invisibility cloaks are [...] Read more.

Metasurfaces, which are ultrathin planar metamaterials arranged in certain global sequences, interact uniquely with the surrounding light field and exhibit unusual effects of light modulation. Many interesting applications have been discovered based on metasurfaces, particularly in invisibility cloaks. However, most invisibility cloaks are limited to working in specific directions. Achieving effectiveness in multiple directions requires the metasurface to be designed with both perception and modulation capabilities. Current multi-directional metasurface cloak systems are implemented with discrete components rather than an integrated sensing component. Here, we propose an intelligent metasurface cloak system that integrates sensing units, resulting in the cloaking effect with the help of a real-time direction sensor and an adaptive feedback control system. A reconfigurable reflective meta-atom based on phase modulation is presented. Sensing units replace parts of the meta-atoms in the designed tunable metasurface, integrating with an FPGA responsible for measuring the direction and frequency of the incident wave, constituting a closed-loop system together with the feedback parts. Experimental results demonstrate that the metasurface cloak system can recognize the different directions of the incoming wave, and can adaptively manipulate the reflected phase of EM waves to conceal objects without any human participation. Full article

(This article belongs to the Special Issue Advances in Metamaterials: Structure, Properties and Applications)

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35 pages, 4084 KiB

Open AccessEditor’s ChoiceArticle

Electrostatically Interacting Wannier Qubits in Curved Space

by Krzysztof Pomorski

Materials 2024, 17(19), 4846; https://doi.org/10.3390/ma17194846 - 30 Sep 2024

Cited by 2 | Viewed by 1230

Abstract

A derivation of a tight-binding model from Schrödinger formalism for various topologies of position-based semiconductor qubits is presented in the case of static and time-dependent electric fields. The simplistic tight-binding model enables the description of single-electron devices at a large integration scale. The [...] Read more.

A derivation of a tight-binding model from Schrödinger formalism for various topologies of position-based semiconductor qubits is presented in the case of static and time-dependent electric fields. The simplistic tight-binding model enables the description of single-electron devices at a large integration scale. The case of two electrostatically Wannier qubits (also known as position-based qubits) in a Schrödinger model is presented with omission of spin degrees of freedom. The concept of programmable quantum matter can be implemented in the chain of coupled semiconductor quantum dots. Highly integrated and developed cryogenic CMOS nanostructures can be mapped to coupled quantum dots, the connectivity of which can be controlled by a voltage applied across the transistor gates as well as using an external magnetic field. Using the anti-correlation principle arising from the Coulomb repulsion interaction between electrons, one can implement classical and quantum inverters (Classical/Quantum Swap Gate) and many other logical gates. The anti-correlation will be weakened due to the fact that the quantumness of the physical process brings about the coexistence of correlation and anti-correlation at the same time. One of the central results presented in this work relies on the appearance of dissipation-like processes and effective potential renormalization building effective barriers in both semiconductors and in superconductors between not bended nanowire regions both in classical and in quantum regimes. The presence of non-straight wire regions is also expressed by the geometrical dissipative quantum Aharonov–Bohm effect in superconductors/semiconductors when one obtains a complex value vector potential-like field. The existence of a Coulomb interaction provides a base for the physical description of an electrostatic Q-Swap gate with any topology using open-loop nanowires, with programmable functionality. We observe strong localization of the wavepacket due to nanowire bending. Therefore, it is not always necessary to build a barrier between two nanowires to obtain two quantum dot systems. On the other hand, the results can be mapped to the problem of an electron in curved space, so they can be expressed with a programmable position-dependent metric embedded in Schrödinger’s equation. The semiconductor quantum dot system is capable of mimicking curved space, providing a bridge between fundamental and applied science in the implementation of single-electron devices. Full article

(This article belongs to the Section Quantum Materials)

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9 pages, 1716 KiB

Open AccessEditor’s ChoiceArticle

Adsorption and Catalytic Reduction of Nitrogen Oxides (NO, N₂O) on Disulfide Cluster Complexes of Cobalt and Iron—A Density Functional Study

by Ellie L. Uzunova and Ivelina M. Georgieva

Materials 2024, 17(19), 4764; https://doi.org/10.3390/ma17194764 - 28 Sep 2024

Viewed by 837

Abstract

The reactivity of nitrogen oxide, NO, as a ligand in complexes with [Fe2-S2] and [Co2-S2] non-planar rhombic cores is examined by density functional theory (DFT). The cobalt-containing nitrosyl complexes are less stable than the iron complexes because the Co-S bonds in the [Co2-S2] [...] Read more.

The reactivity of nitrogen oxide, NO, as a ligand in complexes with [Fe2-S2] and [Co2-S2] non-planar rhombic cores is examined by density functional theory (DFT). The cobalt-containing nitrosyl complexes are less stable than the iron complexes because the Co-S bonds in the [Co2-S2] core are weakened upon NO coordination. Various positions of NO were examined, including its binding to sulfur centers. The release of NO molecules can be monitored photochemically. The ability of NO to form a (NO)₂ dimer provides a favorable route of electrochemical reduction, as protonation significantly stabilizes the dimeric species over the monomers. The quasilinear dimer ONNO, with trans-orientation of oxygen atoms, gains higher stability under protonation and reduction via proton–electron transfer. The first two reduction steps lead to an N₂O intermediate, whose reduction is more energy demanding: in the two latter reaction steps the highest energy barrier for Co₂S₂(CO)₆ is 109 kJ mol⁻¹, and for Fe₂S₂(CO)₆, it is 133 kJ mol⁻¹. Again, the presence of favorable light absorption bands allows for a photochemical route to overcome these energy barriers. All elementary steps are exothermic, and the final products are molecular nitrogen and water. Full article

(This article belongs to the Special Issue Transition Metal Nanomaterials: Synthesis and Photo/Electrocatalytic Performance)

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15 pages, 8933 KiB

Open AccessEditor’s ChoiceArticle

Giant Elastocaloric Effect and Improved Cyclic Stability in a Directionally Solidified (Ni₅₀Mn₃₁Ti₁₉)₉₉B₁ Alloy

by Honglin Wang, Yueping Wang, Guoyao Zhang, Zongbin Li, Jiajing Yang, Jinwei Li, Bo Yang, Haile Yan and Liang Zuo

Materials 2024, 17(19), 4756; https://doi.org/10.3390/ma17194756 - 27 Sep 2024

Cited by 1 | Viewed by 1055

Abstract

Superelastic shape memory alloys with an integration of large elastocaloric response and good cyclability are crucially demanded for the advancement of solid-state elastocaloric cooling technology. In this study, we demonstrate a giant elastocaloric effect with improved cyclic stability in a <001>_A textured [...] Read more.

Superelastic shape memory alloys with an integration of large elastocaloric response and good cyclability are crucially demanded for the advancement of solid-state elastocaloric cooling technology. In this study, we demonstrate a giant elastocaloric effect with improved cyclic stability in a <001>_A textured polycrystalline (Ni₅₀Mn₃₁Ti₁₉)₉₉B₁ alloy developed through directional solidification. It is shown that large adiabatic temperature variation (|ΔT_ad|) values more than 15 K are obtained across the temperature range from 283 K to 373 K. In particular, a giant ΔT_ad up to −27.2 K is achieved by unloading from a relatively low compressive stress of 412 MPa at 303 K. Moreover, persistent |ΔT_ad| values exceeding 8.5 K are sustained for over 12,000 cycles, exhibiting a very low attenuation behavior with a rate of 7.5 × 10⁻⁵ K per cycle. The enhanced elastocaloric properties observed in the present alloy are ascribed to the microstructure texturing as well as the introduction of a secondary phase due to boron alloying. Full article

(This article belongs to the Special Issue Phase Transformation, Functional Properties, and Crystallography of Advanced Materials (Second Volume))

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12 pages, 1462 KiB

Open AccessEditor’s ChoiceArticle

Comparison of Flexural Strength and Wear of Injectable, Flowable and Paste Composite Resins

by Hadi Rajabi, Michael Denny, Kostas Karagiannopoulos and Haralampos Petridis

Materials 2024, 17(19), 4749; https://doi.org/10.3390/ma17194749 - 27 Sep 2024

Cited by 4 | Viewed by 1710

Abstract

(1) Objectives: This study investigated and compared the wear and flexural strength of two highly filled (injectable), one flowable and one paste composite. (2) Methods: Two highly filled flowable composites (G-aenial Universal Injectable and Beautifil Plus F00), a paste composite (Empress Direct) and [...] Read more.

(1) Objectives: This study investigated and compared the wear and flexural strength of two highly filled (injectable), one flowable and one paste composite. (2) Methods: Two highly filled flowable composites (G-aenial Universal Injectable and Beautifil Plus F00), a paste composite (Empress Direct) and a conventional flowable (Tetric EvoFlow) were tested. A two-body wear test was carried out using 10 disc-shaped samples from each group, which were subjected to 200,000 wear machine cycles to simulate wear, followed by Scanning Electron Microscope analysis. Flexural strength was tested using a three-point bend test using 15 beam samples for each of the four groups. Values were statistically compared using one-way analysis of variance (ANOVA) for flexural strength and a Kruskal–Wallis test for wear. (3) Results: The median volume loss for G-aenial Universal Injectable and Beautifil Plus F00 was statistically lower than that of both Empress Direct and Tetric EvoFlow. For flexural strength the two highly filled flowable composites both exhibited statistically higher mean flexural strength values compared to Empress Direct (p < 0.004) and Tetric Evoflow (p < 0.001). There were no statistically significant differences in the values of wear and flexural strength between the two highly filled flowable composites. (4) Conclusions/significance: Highly filled flowable composite resins with nano filler particles outperformed a conventional flowable and a paste composite resin in terms of wear resistance and flexural strength, and may be suitable to use in occlusal, load-bearing areas. Full article

(This article belongs to the Special Issue Materials for Dentistry: Biofunctional Properties and Their Improvement)

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8 pages, 2626 KiB

Open AccessEditor’s ChoiceArticle

Improvement of the Stability of Quantum-Dot Light Emitting Diodes Using Inorganic HfO_x Hole Transport Layer

by Jung Min Yun, Min Ho Park, Yu Bin Kim, Min Jung Choi, Seunghwan Kim, Yeonjin Yi, Soohyung Park and Seong Jun Kang

Materials 2024, 17(19), 4739; https://doi.org/10.3390/ma17194739 - 27 Sep 2024

Viewed by 1297

Abstract

One of the major challenges in QLED research is improving the stability of the devices. In this study, we fabricated all inorganic quantum-dot light emitting diodes (QLEDs) using hafnium oxide (HfO_x) as the hole transport layer (HTL), a material commonly used [...] Read more.

One of the major challenges in QLED research is improving the stability of the devices. In this study, we fabricated all inorganic quantum-dot light emitting diodes (QLEDs) using hafnium oxide (HfO_x) as the hole transport layer (HTL), a material commonly used for insulator. Oxygen vacancies in HfO_x create defect states below the Fermi level, providing a pathway for hole injection. The concentration of these oxygen vacancies can be controlled by the annealing temperature. We optimized the all-inorganic QLEDs with HfO_x as the HTL by changing the annealing temperature. The optimized QLEDs with HfO_x as the HTL showed a maximum luminance and current efficiency of 66,258 cd/m² and 9.7 cd/A, respectively. The fabricated all-inorganic QLEDs exhibited remarkable stability, particularly when compared to devices using organic materials for the HTL. Under extended storage in ambient conditions, the all-inorganic device demonstrated a significantly enhanced operating lifetime (T₅₀) of 5.5 h, which is 11 times longer than that of QLEDs using an organic HTL. These results indicate that the all-inorganic QLEDs structure, with ITO/MoO₃/HfO_x/QDs/ZnMgO/Al, exhibits superior stability compared to organic-inorganic hybrid QLEDs. Full article

(This article belongs to the Special Issue Feature Papers in Materials Physics (2nd Edition))

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21 pages, 2292 KiB

Open AccessEditor’s ChoiceReview

Recent Progress in Laser Powder Bed Fusions Processes of Advanced High-Strength Steels

by Aleksandra Królicka and Julia Malawska

Materials 2024, 17(19), 4699; https://doi.org/10.3390/ma17194699 - 25 Sep 2024

Viewed by 1388

Abstract

This review is focused on the perspectives of the application of Advanced High Strength Steels (AHSSs) in the field of additive technologies directed at the laser powder bed fusion/selective laser melting processes. In principle, AHSSs require significant attention due to their promising mechanical [...] Read more.

This review is focused on the perspectives of the application of Advanced High Strength Steels (AHSSs) in the field of additive technologies directed at the laser powder bed fusion/selective laser melting processes. In principle, AHSSs require significant attention due to their promising mechanical properties for usage in the automotive industry towards reducing the weight of vehicles. Although additive manufacturing represents a promising perspective towards expanding the industrialization of AHSSs in a wider area of their applications, they have not been sufficiently investigated concerning their usage in LPBF/SLM processes. AM techniques enable the fabrication of complex machine parts, including those with a cellular structure, which can contribute to further reducing the weight of vehicles or structures. Maraging steels have recently attracted the attention of researchers, and today are a common grade of steel produced by LPBF techniques. The other group of AHSSs are high-Mn steels with an austenitic matrix characterized by the TRIP and TWIP effects. Less published research has been conducted on medium-Mn steels, which require additional intercritical annealing and preheating during printing. Moreover, the advanced bainitic steels and low-density, high-strength steels represent a new window for further research into the use of the LPBF processes for their fabrication. Full article

(This article belongs to the Special Issue Enhancing In-Use Properties of Advanced Steels)

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30 pages, 13814 KiB

Open AccessEditor’s ChoiceReview

Advances in Resistance Welding of Fiber-Reinforced Thermoplastics

by Zhanyi Geng, Shibao Yu, Shiyuan Wang, Zengtai Tian, Zhonglin Gao, Kaifeng Wang and Yang Li

Materials 2024, 17(19), 4693; https://doi.org/10.3390/ma17194693 - 24 Sep 2024

Cited by 1 | Viewed by 1460

Abstract

Fiber-reinforced thermoplastics (FRTPs) have become a new generation of lightweight materials due to their superior mechanical properties, good weldability and environmental resistance, potential for recycling, etc. The market for FRTPs is expected to grow at a compound annual growth rate (CAGR) of 7.8% [...] Read more.

Fiber-reinforced thermoplastics (FRTPs) have become a new generation of lightweight materials due to their superior mechanical properties, good weldability and environmental resistance, potential for recycling, etc. The market for FRTPs is expected to grow at a compound annual growth rate (CAGR) of 7.8% from 2022 to 2030. Many researchers have been trying to solve the problems in their processing and joining process, and gradually expand their application. Resistance welding is one of the most suitable techniques to join FRTPs. This paper summarizes the research progress of FRTP resistance welding in terms of the basic process of FRTP resistance welding, factors affecting joint performance, joint failure behavior, numerical simulation, weld quality control, and resistance welding of thermoplastic/thermoset composites. The objective of this paper is to provide a deeper insight into the knowledge of FRTP resistance welding and provide reference for the further development and application of FRTP resistance welding. Full article

(This article belongs to the Special Issue Advanced Welding in Alloys and Composites)

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12 pages, 2749 KiB

Open AccessEditor’s ChoiceArticle

Comparison of Fracture Strength of Milled and 3D-Printed Crown Materials According to Occlusal Thickness

by Yeseul Park, Jimin Kim, You-Jung Kang, Eun-Young Shim and Jee-Hwan Kim

Materials 2024, 17(18), 4645; https://doi.org/10.3390/ma17184645 - 22 Sep 2024

Cited by 2 | Viewed by 1764

Abstract

This study aimed to measure the fracture strengths and hardness of final restorative milled and 3D-printed materials and evaluate the appropriate crown thickness for their clinical use for permanent prosthesis. One type of milled material (group M) and two types of 3D-printed materials [...] Read more.

This study aimed to measure the fracture strengths and hardness of final restorative milled and 3D-printed materials and evaluate the appropriate crown thickness for their clinical use for permanent prosthesis. One type of milled material (group M) and two types of 3D-printed materials (groups P1 and P2) were used. Their crown thickness was set to 0.5, 1.0, and 1.5 mm for each group, and the fracture strength was measured. Vickers hardness was measured and analyzed to confirm the hardness of each material. Scanning electron microscopy was taken to observe the surface changes of the 3D-printed materials under loads of 900 and 1500 N. With increased thickness, the fracture strength significantly increased for group M but significantly decreased for group P1. For group P2, the fracture strengths for the thicknesses of 0.5 mm and 1.5 mm significantly differed, but that for 1.0 mm did not differ from those for other thicknesses. The hardness of group M was significantly higher than that of groups P1 and P2. For all thicknesses, the fracture strength was higher than the average occlusal force for all materials; however, an appropriate crown thickness is required depending on the material and component. Full article

(This article belongs to the Special Issue Advances in New Alloys, Polymers and Composites for Biomedical Applications)

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14 pages, 3909 KiB

Open AccessEditor’s ChoiceArticle

Impact of Annealing in Various Atmospheres on Characteristics of Tin-Doped Indium Oxide Layers towards Thermoelectric Applications

by Anna Kaźmierczak-Bałata, Jerzy Bodzenta, Piotr Szperlich, Marcin Jesionek, Anna Michalewicz, Alina Domanowska, Jeyanthinath Mayandi, Vishnukanthan Venkatachalapathy and Andrej Kuznetsov

Materials 2024, 17(18), 4606; https://doi.org/10.3390/ma17184606 - 20 Sep 2024

Viewed by 1107

Abstract

The aim of this work was to investigate the possibility of modifying the physical properties of indium tin oxide (ITO) layers by annealing them in different atmospheres and temperatures. Samples were annealed in vacuum, air, oxygen, nitrogen, carbon dioxide and a mixture of [...] Read more.

The aim of this work was to investigate the possibility of modifying the physical properties of indium tin oxide (ITO) layers by annealing them in different atmospheres and temperatures. Samples were annealed in vacuum, air, oxygen, nitrogen, carbon dioxide and a mixture of nitrogen with hydrogen (NHM) at temperatures from 200 °C to 400 °C. Annealing impact on the crystal structure, optical, electrical, thermal and thermoelectric properties was examined. It has been found from XRD measurements that for samples annealed in air, nitrogen and NHM at 400 °C, the In₂O₃/In₄Sn₃O₁₂ share ratio decreased, resulting in a significant increase of the In₄Sn₃O₁₂ phase. The annealing at the highest temperature in air and nitrogen resulted in larger grains and the mean grain size increase, while vacuum, NHM and carbon dioxide atmospheres caused the decrease in the mean grain size. The post-processing in vacuum and oxidizing atmospheres effected in a drop in optical bandgap and poor electrical properties. The carbon dioxide seems to be an optimal atmosphere to obtain good TE generator parameters—high ZT. The general conclusion is that annealing in different atmospheres allows for controlled changes in the structure and physical properties of ITO layers. Full article

(This article belongs to the Special Issue Disorder-Driven Structure-Property Functionality in Materials: From Material Discovery to Device Development)

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