Crystals

12 pages, 2299 KiB

Open AccessArticle

Lattice Dynamics of Ni_3-xCo_xB₂O₆ Solid Solutions

by Svetlana N. Sofronova, Maksim S. Pavlovskii, Svetlana N. Krylova, Alexander N. Vtyurin and Alexander S. Krylov

Crystals 2024, 14(11), 994; https://doi.org/10.3390/cryst14110994 (registering DOI) - 17 Nov 2024

Abstract

Abstract: On the one hand, Ni_3-xCoxB₂O₆ solid solutions are promising anode materials for lithium batteries, and on the other hand, they have antiferromagnetic properties. This study examines the lattice dynamics of Ni_3-xCo_xB₂ [...] Read more.

Abstract: On the one hand, Ni_3-xCoxB₂O₆ solid solutions are promising anode materials for lithium batteries, and on the other hand, they have antiferromagnetic properties. This study examines the lattice dynamics of Ni_3-xCo_xB₂O₆ solid solutions for x = 0, 1, 2, 3 by means of quantum chemistry and Raman spectroscopy. The vibrational spectra of the compound NiCo₂B₂O₆ have been studied using the polarized Raman spectroscopy method. Good agreement was found between the theoretical and experimental results. As expected, the largest change in frequencies was observed in the modes where the vibrations of the metal ion had a large amplitude. The substitution of cobalt by nickel does not lead to the appearance of soft modes. This fact indicates that the structures of the solid solutions are stable. Full article

(This article belongs to the Section Inorganic Crystalline Materials)

19 pages, 11406 KiB

Open AccessArticle

Mechanical, Tribological, and Corrosion Resistance Properties of (TiAl_ₓCrNbY)N_y High-Entropy Coatings Synthesized Through Hybrid Reactive Magnetron Sputtering

by Nicolae C. Zoita, Mihaela Dinu, Anca C. Parau, Iulian Pana and Adrian E. Kiss

Crystals 2024, 14(11), 993; https://doi.org/10.3390/cryst14110993 (registering DOI) - 17 Nov 2024

Abstract

This study investigates the effects of aluminum and nitrogen content on the microstructure, mechanical properties, and tribological performance of high-entropy coatings based on (TiCrAl_ₓNbY)N_y systems. Using a hybrid magnetron sputtering technique, both metallic and nitride coatings were synthesized and evaluated. [...] Read more.

This study investigates the effects of aluminum and nitrogen content on the microstructure, mechanical properties, and tribological performance of high-entropy coatings based on (TiCrAl_ₓNbY)N_y systems. Using a hybrid magnetron sputtering technique, both metallic and nitride coatings were synthesized and evaluated. Increasing the aluminum concentration led to a transition from a crystalline to a nanocrystalline and nearly amorphous (NC/A) structure, with the TiAl_0.5CrNbY sample (11.8% Al) exhibiting the best balance of hardness (6.8 GPa), elastic modulus (87.1 GPa), and coefficient of friction (0.64). The addition of nitrogen further enhanced these properties, transitioning the coatings to a denser fine-grained FCC structure. The HN2 sample (45.8% nitrogen) displayed the highest hardness (21.8 GPa) but increased brittleness, while the HN1 sample (32.9% nitrogen) provided an optimal balance of hardness (14.3 GPa), elastic modulus (127.5 GPa), coefficient of friction (0.60), and wear resistance (21.2 × 10⁻⁶ mm³/Nm). Electrochemical impedance spectroscopy revealed improved corrosion resistance for the HN1 sample due to its dense microstructure. Overall, the (TiAl_0.5CrNbY)N_0.5 coating achieved the best performance for friction applications, such as break and clutch systems, requiring high coefficients of friction, high wear resistance, and durability. Full article

(This article belongs to the Special Issue Advances of High Entropy Alloys)

9 pages, 2985 KiB

Open AccessArticle

Thermal Regulation of the Acoustic Bandgap in Pentamode Metamaterials

by Jing Cheng, Shujun Liang and Yangyang Chu

Crystals 2024, 14(11), 992; https://doi.org/10.3390/cryst14110992 (registering DOI) - 17 Nov 2024

Abstract

This study used the finite element method to investigate the acoustic bandgap (ABG) characteristics of three-dimensional pentamode metamaterial (PM) structures under the thermal environment, and a method for controlling the PM ABG based on external temperature variation is also proposed. The results indicate [...] Read more.

This study used the finite element method to investigate the acoustic bandgap (ABG) characteristics of three-dimensional pentamode metamaterial (PM) structures under the thermal environment, and a method for controlling the PM ABG based on external temperature variation is also proposed. The results indicate that the complete acoustic bandgap can be obtained for a PM in the thermal environment, which makes the PM combine the bandgap characteristics of phononic crystals. More than that, the bandwidth and locations of ABGs can be effectively manipulated by controlling the temperature. Considering the softening effect of thermal stresses, the ABG gradually moves to lower frequencies as the temperature increases. Based on this, different degrees of ABG tunability can be achieved by changing the thermal environment to propagate or suppress acoustic waves of different frequencies. This work provides the possibility for PMs to realize intelligent regulation of the bandgap. Full article

(This article belongs to the Special Issue Research and Applications of Acoustic Metamaterials)

3 pages, 162 KiB

Open AccessEditorial

Metal Oxides: Crystal Structure, Synthesis and Characterization

by Karolina Siedliska

Crystals 2024, 14(11), 991; https://doi.org/10.3390/cryst14110991 (registering DOI) - 17 Nov 2024

Abstract

Solid metal oxides are widely recognized for their ubiquitous presence and multifaceted utility in everyday applications [...] Full article

(This article belongs to the Special Issue Metal Oxides: Crystal Structure, Synthesis and Characterization)

16 pages, 5705 KiB

Open AccessArticle

Performance and Characterization of Additively Manufactured BST Varactor Enhanced by Photonic Thermal Processing

by Carlos Molina, Ugur Guneroglu, Adnan Zaman, Liguan Li and Jing Wang

Crystals 2024, 14(11), 990; https://doi.org/10.3390/cryst14110990 (registering DOI) - 16 Nov 2024

Abstract

The demand for reconfigurable devices for emerging RF and microwave applications has been growing in recent years, with additive manufacturing and photonic thermal treatment presenting new possibilities to supplement conventional fabrication processes to meet this demand. In this paper, we present the realization [...] Read more.

The demand for reconfigurable devices for emerging RF and microwave applications has been growing in recent years, with additive manufacturing and photonic thermal treatment presenting new possibilities to supplement conventional fabrication processes to meet this demand. In this paper, we present the realization and analysis of barium–strontium–titanate-(Ba_0.5Sr_0.5TiO₃)-based ferroelectric variable capacitors (varactors), which are additively deposited on top of conventionally fabricated interdigitated capacitors and enhanced by photonic thermal processing. The ferroelectric solution with suspended BST nanoparticles is deposited on the device using an ambient spray pyrolysis method and is sintered at low temperatures using photonic thermal processing by leveraging the high surface-to-volume ratio of the BST nanoparticles. The deposited film is qualitatively characterized using SEM imaging and XRD measurements, while the varactor devices are quantitatively characterized by using high-frequency RF measurements from 300 MHz to 10 GHz under an applied DC bias voltage ranging from 0 V to 50 V. We observe a maximum tunability of 60.6% at 1 GHz under an applied electric field of 25 kV/mm (25 V/μm). These results show promise for the implementation of photonic thermal processing and additive manufacturing as a means to integrate reconfigurable ferroelectric varactors in flexible electronics or tightly packaged on-chip applications, where a limited thermal budget hinders the conventional thermal processing. Full article

(This article belongs to the Special Issue Ceramics: Processes, Microstructures, and Properties)

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14 pages, 7747 KiB

Open AccessArticle

Growth and Characterization of High-Quality YTiO₃ Single Crystals: Minimizing Ti⁴⁺ Containing Impurities and TiN Formation

by Yong Liu, David Wenhua Bi and Arnaud Magrez

Crystals 2024, 14(11), 989; https://doi.org/10.3390/cryst14110989 (registering DOI) - 16 Nov 2024

Abstract

We report the growth of YTiO₃ single crystals using different starting materials with the nominal compositions, (1) stoichiometric YTiO₃; (2) oxygen deficient YTiO_2.925; (3) oxygen deficient YTiO_2.85, and different atmospheres, (1) 97%Ar/ 3%H₂; (2) [...] Read more.

We report the growth of YTiO₃ single crystals using different starting materials with the nominal compositions, (1) stoichiometric YTiO₃; (2) oxygen deficient YTiO_2.925; (3) oxygen deficient YTiO_2.85, and different atmospheres, (1) 97%Ar/ 3%H₂; (2) Ar; (3) forming gas 95%N₂/ 5%H₂, using the laser floating zone growth technique. The oxygen-deficient starting materials were prepared by mixing Y₂O₃, Ti₂O₃, and Ti powder according to the YTiO_3-δ stoichiometry. The addition of Ti powder to the starting materials effectively reacts with the oxygen in the floating zone furnace chamber, reducing Ti⁴⁺ ion-containing impurities. High-quality YTiO₃ single crystals with (2 0 0) facet were grown from the starting materials corresponding to the nominal composition YTiO_2.925. YTiO₃ single crystals grown from different starting materials are characteristic of oxygen content of 3 in both pure crystals and crystals containing impurities, revealed by the same oxygen occupancy in single crystal X-ray diffraction measurements. When forming gas was used, a golden TiN coating formed on the surface of rod. Full article

(This article belongs to the Special Issue Advances in Crystal Growth: Pioneering Materials for Tomorrow's Technologies)

20 pages, 20721 KiB

Open AccessArticle

Investigating Exchange Efficiencies of Sodium and Magnesium to Access Lithium from β-Spodumene and Li-Stuffed β-Quartz (γ-Spodumene)

by Joanne Gamage McEvoy, Yves Thibault and Dominique Duguay

Crystals 2024, 14(11), 988; https://doi.org/10.3390/cryst14110988 (registering DOI) - 16 Nov 2024

Abstract

After the high-temperature pretreatment of α-spodumene to induce a phase transition to β-spodumene, a derivative of the silica polymorph keatite, often coexisting with metastable Li-stuffed β-quartz (γ-spodumene)_, the conventional approach to access lithium is through ion exchange with hydrogen using concentrated sulfuric [...] Read more.

After the high-temperature pretreatment of α-spodumene to induce a phase transition to β-spodumene, a derivative of the silica polymorph keatite, often coexisting with metastable Li-stuffed β-quartz (γ-spodumene)_, the conventional approach to access lithium is through ion exchange with hydrogen using concentrated sulfuric acid, which presents drawbacks associated with the production of low-value leaching residues. As sodium and magnesium can produce more interesting aluminosilicate byproducts, this study investigates Na⁺ ↔ Li⁺ and Mg²⁺ ↔ 2 Li⁺ substitution efficiencies in β-spodumene and β-quartz. Thermal annealing at 850 °C of the LiAlSi₂O₆ silica derivatives mixed with an equimolar proportion of Na endmember glass of equivalent stoichiometry (NaAlSi₂O₆) indicates that sodium incorporation in β-quartz is limited, whereas the main constraint for not attaining complete growth to a Na_0.5Li_0.5AlSi₂O₆ β-spodumene solid solution is co-crystallization of minor nepheline. For similar experiments in the equimolar LiAlSi₂O₆-Mg_0.5AlSi₂O₆ system, the efficient substitution of Mg for Li is observed in both β-spodumene and β-quartz, consistent with the alkaline earth having an ionic radius closer to lithium than sodium. Ion exchange at lower temperatures was also evaluated by exposing coexisting β-spodumene and β-quartz to molten salts. In NaNO₃ at 320 °C, sodium for lithium exchange reaches ≈90% in β-spodumene but less than ≈2% in β-quartz, suggesting that to be an efficient lithium recovery route, the formation of β-quartz during the conversion of α-spodumene needs to be minimized. At 525 °C in a molten MgCl₂/KCl medium, although full LiAlSi₂O₆-Mg_0.5AlSi₂O₆ solid solution is observed in β-quartz, structural constraints restrict the incorporation of magnesium in β-spodumene to a Li_0.2Mg_0.4AlSi₂O₆ stoichiometry, limiting lithium recovery to 80%. Full article

(This article belongs to the Collection Topic Collection: Mineralogical Crystallography)

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12 pages, 1667 KiB

Open AccessArticle

Supported and Free-Standing Non-Noble Metal Nanoparticles and Their Catalytic Activity in Hydroconversion of Asphaltenes into Light Hydrocarbons

by Leonid Kustov, Andrei Tarasov, Kristina Kartavova, Valery Khabashesku, Olga Kirichenko, Gennady Kapustin, Alexander Kustov, Evgeny Abkhalimov and Boris Ershov

Crystals 2024, 14(11), 987; https://doi.org/10.3390/cryst14110987 (registering DOI) - 16 Nov 2024

Abstract

The hydroconversion of asphaltenes into light hydrocarbons catalyzed by supported and free-standing non-noble metal nanoparticles was studied. The activity of Ni or Co immobilized on microspherical oxide carriers and Co nanoparticles dispersed in a hydrocarbon solution of asphaltene was found to be higher [...] Read more.

The hydroconversion of asphaltenes into light hydrocarbons catalyzed by supported and free-standing non-noble metal nanoparticles was studied. The activity of Ni or Co immobilized on microspherical oxide carriers and Co nanoparticles dispersed in a hydrocarbon solution of asphaltene was found to be higher than that of a comparative Pt-Pd/Al₂O₃ catalyst. The yield of light products (C₅₊) reached up to 91% on cobalt nanoparticles supported onto alumina microspheres. Full article

(This article belongs to the Special Issue Advances in Nanomaterials and Nanocomposites for Catalytic Applications)

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19 pages, 12552 KiB

Open AccessArticle

Atmosphere-Controlled Solvatomorphic Transitions of Ternary Copper(II) Coordination Compounds in Solid State

by Darko Vušak, Matea Primožić and Biserka Prugovečki

Crystals 2024, 14(11), 986; https://doi.org/10.3390/cryst14110986 - 15 Nov 2024

Abstract

Reactions of copper(II) sulfate with 2,2′-bipyridine (bpy) and l-serine (l-Hser) were investigated using different solution-based and mechanochemical methods. Four new ternary coordination compounds were obtained by solution-based synthesis, and three of them additionally via the liquid-assisted mechanochemical method: α-[Cu( [...] Read more.

Reactions of copper(II) sulfate with 2,2′-bipyridine (bpy) and l-serine (l-Hser) were investigated using different solution-based and mechanochemical methods. Four new ternary coordination compounds were obtained by solution-based synthesis, and three of them additionally via the liquid-assisted mechanochemical method: α-[Cu(l-Ser)(H₂O)(bpy)]₂SO₄ (1a-α), β-[Cu(l-Ser)(H₂O)(bpy)]₂SO₄ (1a-β), [Cu(l-Ser)(H₂O)(bpy)]₂SO₄·6H₂O (1a∙6H₂O), and [Cu(l-Ser)(bpy)(CH₃OH)]₂SO₄·2CH₃OH (1b∙3CH₃OH). The compounds were characterized by single-crystal and powder X-ray diffraction, infrared spectroscopy, and thermal analysis. Structural studies revealed two polymorphs (1a-α and 1a-β) and two solvatomorphs (1a∙6H₂O and 1b∙3CH₃OH). To investigate the stability of the compounds, crystalline samples were exposed to different conditions of relative humidity (RH) and an atmosphere of methanol vapours. Successful solid-state transformation of 1a∙6H₂O into 1a-α was established at lower RH values, and vice versa at higher RH values, while both compounds partially transitioned to 1a-β in the atmosphere of methanol vapours. Compound 1b∙3CH₃OH decomposed spontaneously into 1a-α by standing in the air. All of the investigated structural transformations were underpinned with proposed mechanisms. Additionally, 1a-α showed moderate in vitro antiproliferative activity toward a human breast cancer cell line (MCF-7), a human colon cancer cell line (HCT116), and a human lung cancer cell line (H460). Full article

(This article belongs to the Section Inorganic Crystalline Materials)

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18 pages, 6573 KiB

Open AccessArticle

Preliminary Spectroscopic Observations of Marble-Hosted Rubies, Marginal Host Marbles, and Transition Zones Between Marbles and Rubies on Samples from Afghanistan, Myanmar, and Pakistan

by Chen Fan, Yung-Chin Ding and Wing-Tak Lui

Crystals 2024, 14(11), 985; https://doi.org/10.3390/cryst14110985 - 15 Nov 2024

Abstract

This study focusses on the spectroscopic observation of marbles, rubies and the transition zone between ruby and its hosted marble that may distinguish the origin of ruby. Samples of ruby-bearing marble were obtained from Afghanistan, Myanmar, and Pakistan. Energy-dispersive X-ray fluorescence was used [...] Read more.

This study focusses on the spectroscopic observation of marbles, rubies and the transition zone between ruby and its hosted marble that may distinguish the origin of ruby. Samples of ruby-bearing marble were obtained from Afghanistan, Myanmar, and Pakistan. Energy-dispersive X-ray fluorescence was used to analyze the chemical compositions. Although the content of other elements in the marble varied with the origin, the Cl content was quite constant. A diagram of the trace elements Fe and Ga was used to determine the origins of the marble-hosted rubies. X-ray diffraction was used to verify the structure phases, where trioctahedral mica, plagioclase, quartz, and alkali feldspar were found in marbles. Ultraviolet–visible spectrophotometry was used for rubies, where a 659 nm fluoresce peak was found in the Myanmar ruby sample, which could make Myanmar ruby redder and more sought after. The bonding of elements and inclusions of the samples were analyzed using Fourier transform infrared spectroscopy, Raman spectroscopy, and photoluminescence. A FTIR peak at 630 cm⁻¹ is found to be useful in judging the temperature of ruby formation. Scanning electron microscopy and energy-dispersive X-ray spectroscopy were used to analyze the variation of the transition zone, which revealed that the boundary was a gradation zone. Concentrations of Al₂0₃ increased in this zone, but CaCO₃ concentrations decreased. Full article

(This article belongs to the Collection Topic Collection: Mineralogical Crystallography)

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9 pages, 2658 KiB

Open AccessArticle

Performance Enhancement of MoSe₂ and WSe₂ Based Junction Field Effect Transistors with Gate-All-Around Structure

by Changlim Woo, Abdelkader Abderrahmane, Pangum Jung and Pilju Ko

Crystals 2024, 14(11), 984; https://doi.org/10.3390/cryst14110984 - 15 Nov 2024

Abstract

Recently, two-dimensional materials have gained significant attention due to their outstanding properties such as high charge mobility, mechanical strength, and electrical characteristics. These materials are considered one of the most promising solutions to overcome the limitations of semiconductor technology and are being utilized [...] Read more.

Recently, two-dimensional materials have gained significant attention due to their outstanding properties such as high charge mobility, mechanical strength, and electrical characteristics. These materials are considered one of the most promising solutions to overcome the limitations of semiconductor technology and are being utilized in various semiconductor device research. In particular, molybdenum diselenide (MoSe₂) and tungsten diselenide (WSe₂) are actively being developed for device applications due to their high electron mobility, optical properties, and electrical characteristics. In this study, we fabricated MoSe₂ and WSe₂-based junction field-effect transistors (JFET) and further deposited two-dimensional materials on the same device to fabricate and compare JFETs with a gate-all-around (GAA) structure. The research results showed that the GAA-structure JFET exhibited performance improvements in drain current, subthreshold swing (SS) transconductance (gm), and mobility, achieving enhancements ranging from a minimum of 1.2 times to a maximum of 10 times compared to conventional JFET. Full article

(This article belongs to the Special Issue Advanced Research in 2D Materials)

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11 pages, 4471 KiB

Open AccessArticle

Creep Behavior of a Single Crystal Nickel-Based Superalloy Containing High Concentrations of Re/Ru at an Intermediate Temperature

by Ning Tian, Tai Meng, Shulei Sun, Shunke Zhang and Danping Dang

Crystals 2024, 14(11), 983; https://doi.org/10.3390/cryst14110983 - 14 Nov 2024

Abstract

The deformation and damage mechanisms of a single crystal nickel-based superalloy containing 6.0%Re/5.0%Ru were studied through creep performance tests at 800 °C/860–880 MPa, microstructure and morphology observation, and dislocation configuration analyzation. It was found that, during the creep process at the intermediate temperature, [...] Read more.

The deformation and damage mechanisms of a single crystal nickel-based superalloy containing 6.0%Re/5.0%Ru were studied through creep performance tests at 800 °C/860–880 MPa, microstructure and morphology observation, and dislocation configuration analyzation. It was found that, during the creep process at the intermediate temperature, the γ′ phase does not form a raft-like structure. After a creep fracture, the distortion degree of the cubic γ′ phase becomes greater when the observation region is closer to the fracture. The alloy has a long creep life at 800 °C, and the dislocation slipping or climbing in the γ matrix is the deformation mechanism at the early and middle creep stages. At the later creep stage, the γ′ phase is sheared by dislocations. Because of the low stacking-fault energy of the alloy, the <110> superdislocation shearing into the γ′ phase can decompose on the {111} plane to form a (1/3) <112> partial dislocation and stacking-fault configuration or cross-slip to the {100} plane to form the Kear–Wilsdorf (K-W) lock, which greatly improves the creep resistance of the alloy. At the later creep stage, the primary/secondary slip systems in the alloy are activated alternately, resulting in micro-cracks at the intersection of the two slip systems. As the creep progresses, the initiated cracks spread and propagate in the γ matrix phase along a direction normal to the stress axis and connect with each other until creep fracture occurs. This is the fracture mechanism of the alloy during creep at the medium temperature. Full article

(This article belongs to the Section Crystal Engineering)

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13 pages, 2412 KiB

Open AccessArticle

Preparation and Study of Poly(Vinylidene Fluoride-Co-Hexafluoropropylene)-Based Composite Solid Electrolytes

by Meihong Huang, Lingxiao Lan, Pengcheng Shen, Zhiyong Liang, Feng Wang, Yuling Zhong, Chaoqun Wu, Fanxiao Kong and Qicheng Hu

Crystals 2024, 14(11), 982; https://doi.org/10.3390/cryst14110982 - 14 Nov 2024

Abstract

Solid-state electrolytes are widely anticipated to revitalize lithium-ion batteries with high energy density and safety. However, low ionic conductivity and high interfacial resistance at room temperature pose challenges for practical applications. This study combines the rigid oxide electrolyte LLZTO with the flexible polymer [...] Read more.

Solid-state electrolytes are widely anticipated to revitalize lithium-ion batteries with high energy density and safety. However, low ionic conductivity and high interfacial resistance at room temperature pose challenges for practical applications. This study combines the rigid oxide electrolyte LLZTO with the flexible polymer electrolyte poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) to achieve effective coupling of rigidity and flexibility. The semi-interpenetrating network structure endows the PEL composite solid electrolyte with excellent lithium-ion transport capabilities, resulting in an ionic conductivity of up to 5.1 × 10⁻⁴S cm⁻¹ and lithium-ion transference number of 0.41. The assembled LiFePO₄/PEL/Li solid-state battery demonstrates an initial discharge capacity of 132 mAh g⁻¹ at a rate of 0.1 C. After 100 charge–discharge cycles, the capacity retention is 81%. This research provides a promising strategy for preparing composite solid electrolytes in solid-state lithium-ion batteries. Full article

(This article belongs to the Special Issue Research on Electrolytes and Energy Storage Materials)

24 pages, 6021 KiB

Open AccessArticle

Structural, Optical, Magnetic, and Dielectric Investigations of Pure and Co-Doped La_0.67Sr_0.33Mn_1-x-yZn_xCo_yO₃ Manganites with (0.00 < x + y < 0.20)

by Mansour Mohamed, A. Sedky, Abdullah S. Alshammari, Z. R. Khan, M. Bouzidi and Marzook S. Alshammari

Crystals 2024, 14(11), 981; https://doi.org/10.3390/cryst14110981 - 14 Nov 2024

Abstract

Here, we report the structural, optical, magnetic, and dielectric properties of La_0.67Sr_0.33Mn_1-x-yZn_xCo_yO₃ manganite with various x and y values (0.025 < x + y < 0.20). The pure and co-doped samples are [...] Read more.

Here, we report the structural, optical, magnetic, and dielectric properties of La_0.67Sr_0.33Mn_1-x-yZn_xCo_yO₃ manganite with various x and y values (0.025 < x + y < 0.20). The pure and co-doped samples are called S1, S2, S3, S4, and S5, with (x + y) = 0.00, 0.025, 0.05, 0.10, and 0.20, respectively. The XRD confirmed a monoclinic structure for all the samples, such that the unit cell volume and the size of the crystallite and grain were generally decreased by increasing the co-doping content (x + y). The opposite was true for the behaviors of the porosity, the Debye temperature, and the elastic modulus. The energy gap E_g was 3.85 eV for S1, but it decreased to 3.82, 3.75, and 3.65 eV for S2, S5, and S3. Meanwhile, it increased and went to its maximum value of 3.95 eV for S4. The values of the single and dispersion energies (E_o, E_d) were 9.55 and 41.88 eV for S1, but they were decreased by co-doping. The samples exhibited paramagnetic behaviors at 300 K, but they showed ferromagnetic behaviors at 10 K. For both temperatures, the saturated magnetizations (M_s) were increased by increasing the co-doping content and they reached their maximum values of 1.27 and 15.08 (emu/g) for S4. At 300 K, the co-doping changed the magnetic material from hard to soft, but it changed from soft to hard at 10 K. In field cooling (FC), the samples showed diamagnetic regime behavior (M < 0) below 80 K, but this behavior was completely absent for zero field cooling (ZFC). In parallel, co-doping of up to 0.10 (S4) decreased the dielectric constant, AC conductivity, and effective capacitance, whereas the electric modulus, impedance, and bulk resistance were increased. The analysis of the electric modulus showed the presence of relaxation peaks for all the samples. These outcomes show a good correlation between the different properties and indicate that co-doping of up to 0.10 of Zn and Co in place of Mn in La:113 compounds is beneficial for elastic deformation, optoelectronics, Li-batteries, and spintronic devices. Full article

(This article belongs to the Special Issue Crystal Structures and Magnetic Interactions of Magnetic Materials)

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12 pages, 894 KiB

Open AccessArticle

Micro-Computed Tomographic Evaluation of the Shaping Ability of Vortex Blue and TruNatomy^TM Ni-Ti Rotary Systems

by Batool Alghamdi, Mey Al-Habib, Mona Alsulaiman, Lina Bahanan, Ali Alrahlah, Leonel S. J. Bautista, Sarah Bukhari, Mohammed Howait and Loai Alsofi

Crystals 2024, 14(11), 980; https://doi.org/10.3390/cryst14110980 - 14 Nov 2024

Abstract

This study aimed to assess and evaluate the canal shaping ability of two different Ni-Ti rotary systems, Vortex Blue (VB) and TruNatomy (TN), using micro-computed tomography in extracted premolars. A total of 20 extracted bifurcated maxillary first premolars with two separate canals were [...] Read more.

This study aimed to assess and evaluate the canal shaping ability of two different Ni-Ti rotary systems, Vortex Blue (VB) and TruNatomy (TN), using micro-computed tomography in extracted premolars. A total of 20 extracted bifurcated maxillary first premolars with two separate canals were randomly divided into two groups and prepared with either VB 35/0.04 (Dentsply Maillefer, Ballaigues, Switzerland) or TN Medium 36/0.03 (Dentsply Sirona). Pre- and post-instrumentation micro-CT scans were analyzed to measure the following parameters: percentage of untouched canal surface area, changes in canal surface area, changes in canal volume, structural model index (SMI), changes in canal angulation, changes in dentin thickness, transportation, and centering ability. Statistical analysis was performed with a significance level set at p-value < 0.05. Both VB and TN files showed a significant increase in the basic canal geometry parameters including canal surface area and canal volume. Both file systems showed no significant changes in SMI or dentin thickness after canal instrumentation (p > 0.05). Some degree of canal transportation and a similar centering ability ratio with no significant difference were observed in both file systems (p > 0.05). TN files showed less pre-cervical dentin removal when compared to VB files. A significant difference was found in the TN group regarding the dentin removal between coronal and apical thirds (p = 0.03). Both VB and TN files produced comparable root canal preparation with no considerable shaping mishaps and errors. Both files showed minimum canal transportation and minimum straightening of the canal curvature. TN files removed less pre-cervical dentin than apical dentin. Full article

(This article belongs to the Special Issue Shape Memory Alloys: Recent Advances and Future Perspectives)

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16 pages, 4348 KiB

Open AccessArticle

Understanding the Interface Characteristics Between TiB₂(0001) and L1₂-Al₃Zr(001): A First-Principles Investigation

by Xingzhi Pang, Loujiang Yang, Hang Nong, Mingjun Pang, Gaobao Wang, Jian Li, Zhenchao Chen, Wei Zeng, Zhihang Xiao, Zengxiang Yang and Hongqun Tang

Crystals 2024, 14(11), 979; https://doi.org/10.3390/cryst14110979 - 14 Nov 2024

Abstract

This study employs first-principles calculation methods to explore the characteristics of the TiB₂(0001)/L1₂-Al₃Zr(001) interface, including the atomic structure, adhesion work, interfacial energy, and electronic structure of various interface models. Considering four different terminations and three different stacking [...] Read more.

This study employs first-principles calculation methods to explore the characteristics of the TiB₂(0001)/L1₂-Al₃Zr(001) interface, including the atomic structure, adhesion work, interfacial energy, and electronic structure of various interface models. Considering four different terminations and three different stacking positions, twelve potential interface models were investigated. Surface tests revealed that a stable interface could be formed when a 9-layer TiB₂(0001) surface is combined with a 7-layer ZrAl-terminated and a 9-layer Al-terminated Al₃Zr(001) surface. Among these interfaces, the bridge-site stacking at the T/Al termination (TAB), hollow-site stacking at the Ti/ZrAl termination (TZH), top-site stacking at the B/Al termination (BAT), and hollow-site stacking at the B/ZrAl termination (BZH) were identified as the optimal structures. Particularly, the TAB interface exhibits the strongest adhesion strength and the lowest surface energy, indicating the highest stability. A Detailed analysis of the electronic structure further reveals that most interfaces predominantly exhibit covalent bonding, with the TAB, TZH, and BZH interfaces primarily featuring covalent bonds, while the BAT interface displays a combination of ionic and covalent bonds. The study ultimately ranks the stability of the interfaces from highest to lowest as TAB, BZH, TZH, and BAT. Full article

(This article belongs to the Special Issue Design, Development and Processing of Aluminium Alloys and Their Composite Materials)

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12 pages, 4114 KiB

Open AccessArticle

Intermolecular Interactions in Molecular Ferroelectric Zinc Complexes of Cinchonine

by Marko Očić and Lidija Androš Dubraja

Crystals 2024, 14(11), 978; https://doi.org/10.3390/cryst14110978 - 13 Nov 2024

Abstract

The use of chiral organic ligands as linkers and metal ion nodes with specific coordination geometry is an effective strategy for creating homochiral structures with potential ferroelectric properties. Natural Cinchona alkaloids, e.g., quinine and cinchonine, as compounds with a polar quinuclidine fragment and [...] Read more.

The use of chiral organic ligands as linkers and metal ion nodes with specific coordination geometry is an effective strategy for creating homochiral structures with potential ferroelectric properties. Natural Cinchona alkaloids, e.g., quinine and cinchonine, as compounds with a polar quinuclidine fragment and aromatic quinoline ring, are suitable candidates for the construction of molecular ferroelectrics. In this work, the compounds [CnZnCl₃]·MeOH and [CnZnBr₃]·MeOH, which crystallize in the ferroelectric polar space group P2₁, were prepared by reacting the cinchoninium cation (Cn) with zinc(II) chloride or zinc(II) bromide. The structure of [CnZnBr₃]·MeOH was determined from single-crystal X-ray diffraction analysis and was isostructural with the previously reported chloride analog [CnZnCl₃]·MeOH. The compounds were characterized by infrared spectroscopy, and their thermal stability was determined by thermogravimetric analysis and temperature-modulated powder X-ray diffraction experiments. The intermolecular interactions of the different cinchoninium halogenometalate complexes were evaluated and compared. Full article

(This article belongs to the Special Issue Polycrystalline Materials–from Design to (Micro)Structural Characterization and Applications)

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12 pages, 6747 KiB

Open AccessArticle

Solution Strengthening and Short-Range Order in Cold-Drawn Pearlitic Steel Wires

by Gang Zhao, Jianyu Jiao, Yan Wu, Fengmei Bai, Hongwei Zhou, Jun Xue, Yixuan Zhu and Guangwen Zheng

Crystals 2024, 14(11), 977; https://doi.org/10.3390/cryst14110977 - 13 Nov 2024

Abstract

Pearlitic steel rods are subjected to cold-drawing processes to produce pearlitic steel wires with true strains ranging from 0.81 to 2.18. Tensile tests are utilized to attain mechanical properties of cold-drawn pearlitic steel wires. TEM and XRD investigations were performed on the microstructure [...] Read more.

Pearlitic steel rods are subjected to cold-drawing processes to produce pearlitic steel wires with true strains ranging from 0.81 to 2.18. Tensile tests are utilized to attain mechanical properties of cold-drawn pearlitic steel wires. TEM and XRD investigations were performed on the microstructure of the cold-drawn steel wires. With an increasing cold-drawn strain, both the interlamellar spacing and cementite lamellae thickness decrease, while the dislocation density significantly increases. The drawn wire has a tensile strength of 2170 MPa when the true stain reaches 2.18. Deformation-induced cementite dissolution occurs during cold-drawing progress, which releases many C atoms. The findings indicate that the supersaturation of C is heterogeneously distributed in the ferrite matrix. The ordered distribution of the released C in ferrite phases creates short-range order (SRO). SRO clusters and disordered Cottrell atmospheres contribute to solution strengthening, which, together with dislocation strengthening and interlamellar boundary strengthening, form an effective strengthening mechanism in cold-drawn pearlitic steel wires. Our work provides new insights into carbon redistribution and the mechanism of solution strengthening within ferrous phases. Full article

(This article belongs to the Special Issue Microstructure and Properties of Metals and Alloys)

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17 pages, 13365 KiB

Open AccessArticle

On the Peculiarities of Wire-Feed Electron Beam Additive Manufacturing (WEBAM) of Nickel Alloy–Copper Bimetal Nozzle Samples

by Kseniya Osipovich, Vyacheslav Semenchuk, Andrey Chumaevskii, Denis Gurianov, Alexander M. Korsunsky, Valery Rubtsov and Evgeny Kolubaev

Crystals 2024, 14(11), 976; https://doi.org/10.3390/cryst14110976 - 13 Nov 2024

Abstract

In order to gain insight into the unique characteristics of manufacturing large-scale products with intricate geometries, experimental nozzle-shaped samples were created using wire-feed electron beam additive technology. Bimetal samples were fabricated from nickel-based alloy and copper. Two distinct approaches were employed, utilizing varying [...] Read more.

In order to gain insight into the unique characteristics of manufacturing large-scale products with intricate geometries, experimental nozzle-shaped samples were created using wire-feed electron beam additive technology. Bimetal samples were fabricated from nickel-based alloy and copper. Two distinct approaches were employed, utilizing varying substrate thicknesses and differing fabrication parameters. The two approaches were the subject of analysis and comparison through the examination of the surface morphology of the samples using optical microscopy, scanning electron microscopy, and X-ray diffraction analysis. It has been demonstrated that the variation in heat flux distributions resulting from varying the substrate thicknesses gives rise to the development of disparate angles of grain boundary orientation relative to the substrate. Furthermore, it is demonstrated that suboptimal choice of the fabrication parameters results in large disparities in the crystallization times, both at the level of sample as a whole and within the same material volume. For example, for the sample manufacturing by Mode I, the macrostructure of the layers is distinguished by the presence of non-uniformity in their geometric dimensions and the presence of unmelted wire fragments. In order to characterize the experimental nozzle-shaped samples, microhardness was measured, uniaxial tensile tests were performed, and thermal diffusivity was determined. The microhardness profiles and the mechanical properties exhibit a higher degree of strength than those observed in pure copper samples and a lower degree of strength than those observed in Inconel 625 samples obtained through the same methodology. The thermal diffusivity values of the samples are sufficiently close to one another and align with the properties of the corresponding materials in their state after casting or rolling. The data discussed above indicate that Mode II yields the optimal mechanical properties of the sample due to the high cooling rate, which influences the structural and phase state of the resulting products. It was thus concluded that the experimental samples grown by Mode II on a thinner substrate exhibited the best formability. Full article

(This article belongs to the Special Issue Modern Technologies in the Manufacturing of Metal Matrix Composites)

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