Ceramics

13 pages, 3349 KiB

Open AccessArticle

Compositionally Disordered Ceramic (Gd,Y,Tb,Ce)₃Al₂Ga₃O₁₂ Phosphor for an Effective Conversion of Isotopes’ Ionizing Radiation to Light

by Mikhail V. Korzhik, Petr V. Karpyuk, Aliaksei G. Bondarau, Daria E. Lelecova, Vitaly A. Mechinsky, Vladimir Pustovarov, Vasilii Retivov, Valentina G. Smyslova, Dmitry Tavrunov and Denis N. Yanushevich

Ceramics 2023, 6(3), 1900-1912; https://doi.org/10.3390/ceramics6030117 - 21 Sep 2023

Viewed by 1575

Abstract

Compositionally disordered crystalline material (Gd,Y,Tb,Ce)₃Al₂Ga₃O₁₂ was demonstrated to be a highly effective converter of corpuscular ionizing radiation into light. The material was found to be radiation-tolerant to an intense 10 MeV electron beam and had a [...] Read more.

Compositionally disordered crystalline material (Gd,Y,Tb,Ce)₃Al₂Ga₃O₁₂ was demonstrated to be a highly effective converter of corpuscular ionizing radiation into light. The material was found to be radiation-tolerant to an intense 10 MeV electron beam and had a low temperature dependence on light yield. These findings open an opportunity to utilize the developed material to create long-living, high-flux sources of optical photons under the irradiation of isotope sources. Besides the purposes of the measurement of ionizing radiation by the scintillation method in a harsh irradiation environment, this puts forward the exploiting of the developed material for indirect isotope voltaic batteries and the consideration of a photon engine for travel beyond the solar system, where solar wind force becomes negligible. Full article

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6 pages, 2163 KiB

Open AccessCommunication

Metal Halide Perovskite Light-Emitting Transistor with Tunable Emission Based on Electrically Doped Semiconductor Nanocrystal-Based Microcavities

by Francesco Scotognella

Ceramics 2023, 6(3), 1894-1899; https://doi.org/10.3390/ceramics6030116 - 11 Sep 2023

Viewed by 1722

Abstract

Electroluminescence of metal halide perovskites has been widely reported via the fabrication and optimization of light-emitting diodes and light-emitting transistors. Light-emitting transistors are particularly interesting owing to the additional control of the gate voltage on the electroluminescence. In this work, the design of [...] Read more.

Electroluminescence of metal halide perovskites has been widely reported via the fabrication and optimization of light-emitting diodes and light-emitting transistors. Light-emitting transistors are particularly interesting owing to the additional control of the gate voltage on the electroluminescence. In this work, the design of a microcavity, with a defect mode that can be tuned with an applied voltage, integrated with a metal halide light-emitting transistor is shown. The optical properties of the device have been simulated with the transfer matrix method, considering the wavelength-dependent refractive indexes of all the employed materials. The tunability of the microcavity has been obtained via the employment of doped semiconductor nanocrystalline films, which show a tunable plasma frequency and, thus, a tunable refractive index as a function of the applied voltage. Consequently, the tunability of the electroluminescence of the metal halide perovskite light-emitting transistor has been demonstrated. Full article

(This article belongs to the Special Issue Advances in Ceramics, 2nd Edition)

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15 pages, 4284 KiB

Open AccessArticle

Analytical Model of Deformation of a Functionally Graded Ceramic Coating under Local Load

by Ivan Shatskyi, Mykola Makoviichuk, Liubomyr Ropyak and Andrii Velychkovych

Ceramics 2023, 6(3), 1879-1893; https://doi.org/10.3390/ceramics6030115 - 7 Sep 2023

Cited by 9 | Viewed by 1706

Abstract

In this article, an analytical approach to the study of the behavior of functionally graded FG coatings under local load is developed. The method is suitable for coatings with a specific structure. We consider that the coating can be conditionally divided into two [...] Read more.

In this article, an analytical approach to the study of the behavior of functionally graded FG coatings under local load is developed. The method is suitable for coatings with a specific structure. We consider that the coating can be conditionally divided into two zones: a relatively rigid outer and a relatively compliant inner. The outer layer is modeled by a non-homogeneous plate that bends. We submit the inner substrate to the hypothesis of a non-homogeneous thin Winkler layer. The solution of the formulated boundary value problem is constructed in analytical form. Simulation examples for FG aluminum oxide coatings grown from aluminum sprayed on steel and from compact alloy D16T are considered. The distributions of equivalent stresses, safety factors and normalized equivalent stresses in the coatings are studied. It is noted that in a heterogeneous material, the location of the minimum of the safety factor does not always coincide with the location of the maximum of the equivalent stress. Full article

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18 pages, 5331 KiB

Open AccessArticle

Developing Geopolymer Concrete by Using Ferronickel Slag and Ground-Granulated Blast-Furnace Slag

by Quang Dieu Nguyen and Arnaud Castel

Ceramics 2023, 6(3), 1861-1878; https://doi.org/10.3390/ceramics6030114 - 6 Sep 2023

Cited by 7 | Viewed by 2121

Abstract

Geopolymer concrete is gaining recognition as an environmentally friendly alternative to traditional cement-based materials, offering potential solutions for reducing the carbon emissions of the construction industry. This study aims to develop GGBFS–FNS geopolymers utilising ferronickel slag (FNS) and ground-granulated blast-furnace slag (GGBFS). Ground [...] Read more.

Geopolymer concrete is gaining recognition as an environmentally friendly alternative to traditional cement-based materials, offering potential solutions for reducing the carbon emissions of the construction industry. This study aims to develop GGBFS–FNS geopolymers utilising ferronickel slag (FNS) and ground-granulated blast-furnace slag (GGBFS). Ground FNS (GFNS) is a potential candidate for replacing fly ash in geopolymers. This research aims to develop for the first time a GGBFS–FNS alkali-activated concrete. Numerous trials were conducted including different GGBFS–FNS blend percentages, several chemical admixtures and varying activator concentrations to develop the optimal binder mix composition. The effects of different chemical admixtures on the properties of geopolymer pastes, mortars, and concretes were investigated. The study evaluated setting time, compressive strength, shrinkage, and physical and durability properties. The results indicate that conventional admixtures have limited impact on the setting time, while increasing the water/solid ratio and decreasing the GGBFS content could extend the initial and final setting times. The presence of FNS aggregate could improve the compressive strength of geopolymer mortars. The water absorber admixture was highly effective in reducing shrinkage and increasing chloride diffusion resistance. The geopolymer mix containing 50 wt.% GFNS and 50 wt.% GGBFS with the presence of the water absorber admixture presented high chloride diffusion resistance, non-reactivity to the alkali–silica reaction and high sulphate resistance. Overall, the GGBFS–FNS geopolymers exhibited promising potential for engineering applications as an environmentally friendly material, particularly in aggressive environments. Full article

(This article belongs to the Special Issue The Production Processes and Applications of Geopolymers)

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11 pages, 8404 KiB

Open AccessArticle

Anodic Performance of Ni–BCZY and Ni–BCZY–GDC Films on BCZY Electrolytes

by Yoshiteru Itagaki, Yota Kumamoto, Susumu Okayama and Hiromichi Aono

Ceramics 2023, 6(3), 1850-1860; https://doi.org/10.3390/ceramics6030113 - 5 Sep 2023

Viewed by 1624

Abstract

Cermet films consisting of Ni, BaCe_0.4Zr_0.4Y_0.2O_3−δ (BCZY), and Gd_0.1Ce_0.9O_x (GDC), specifically, 60 wt%Ni–BCZY, 60 wt%Ni–BCZY–GDC, and 60 wt%Ni–GDC, were formed on BCZY electrolyte supports as anodes of proton ceramic fuel cells [...] Read more.

Cermet films consisting of Ni, BaCe_0.4Zr_0.4Y_0.2O_3−δ (BCZY), and Gd_0.1Ce_0.9O_x (GDC), specifically, 60 wt%Ni–BCZY, 60 wt%Ni–BCZY–GDC, and 60 wt%Ni–GDC, were formed on BCZY electrolyte supports as anodes of proton ceramic fuel cells (PCFCs). The Ni grain size in these films after sintering at 1450 °C was around 2 μm. The GDC addition did not affect the Ni grain size in the case of the BCZY matrix. The anodic properties greatly depended on the oxide phase composition and worsened with increasing the GDC content. This probably occurred because of the addition of GDC, which has low proton conductivity and inhibited the proton conduction path of BCZY, reducing three-phase boundaries in the anode bulk. Since BCZY has a lower grain growth rate during sintering than BaCe_0.8Y_0.2O_3−δ, the Ni grain growth was likely suppressed by the surrounding Ni grains containing small BCZY grains. Full article

(This article belongs to the Topic Metal-Ceramic Composites: Microstructure Tailoring, Properties and Applications)

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10 pages, 3825 KiB

Open AccessArticle

Phase Formation and Properties of Multicomponent Solid Solutions Based on Ba(Ti, Zr)O₃ and AgNbO₃ for Environmentally Friendly High-Efficiency Energy Storage

by Dmitry V. Volkov, Ekaterina V. Glazunova, Lydia A. Shilkina, Aleksandr V. Nazarenko, Aleksey A. Pavelko, Vyacheslav A. Bobylev, Larisa A. Reznichenko and Ilya A. Verbenko

Ceramics 2023, 6(3), 1840-1849; https://doi.org/10.3390/ceramics6030112 - 26 Aug 2023

Viewed by 1418

Abstract

This paper investigates the processes of phase formation of solid solutions of (1 − x)BaTi_0.85Zr_0.15O₃ − xAgNbO₃ where x = 0, 0.03, 0.06, 0.09. The optimal temperatures of synthesis and sintering are determined. From the [...] Read more.

This paper investigates the processes of phase formation of solid solutions of (1 − x)BaTi_0.85Zr_0.15O₃ − xAgNbO₃ where x = 0, 0.03, 0.06, 0.09. The optimal temperatures of synthesis and sintering are determined. From the results of X-ray diffraction analysis, it follows that all solid solutions have a perovskite-type structure. Analysis of the microstructure showed that the average grain size decreases at concentrations x = 0.03 and 0.06. Correlations between the cationic composition and dielectric characteristics of the studied solid solutions have been established. The values of the total stored energy and efficiency are determined. The maximum stored energy was found for a solid solution with x = 0.03 and amounted to 0.074 J∙cm⁻³ with an efficiency of 76.5%. Full article

(This article belongs to the Special Issue Advances in Ferroelectric, Construction, Luminescent Ceramics and Crystals)

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14 pages, 13306 KiB

Open AccessArticle

An Investigation of Iodovanadinite Wasteforms for the Immobilisation of Radio-Iodine and Technetium

by Daniel J. Bailey, Erik V. Johnstone, Martin C. Stennett, Claire L. Corkhill and Neil C. Hyatt

Ceramics 2023, 6(3), 1826-1839; https://doi.org/10.3390/ceramics6030111 - 24 Aug 2023

Viewed by 1573

Abstract

⁹⁹Tc and ¹²⁹I are two long-lived, highly soluble and mobile fission products that pose a long-term hazard. A proposed wasteform for the disposal of radio-iodine is iodovanadinite (Pb₅(VO₄)₃I), an apatite-structured vanadate. In this investigation, a [...] Read more.

⁹⁹Tc and ¹²⁹I are two long-lived, highly soluble and mobile fission products that pose a long-term hazard. A proposed wasteform for the disposal of radio-iodine is iodovanadinite (Pb₅(VO₄)₃I), an apatite-structured vanadate. In this investigation, a suite of potential iodovanadinite wasteforms designed for the co-disposal of Tc and I or the sole disposal of I were synthesised via hot isostatic pressing (with Mo as a surrogate for Tc). It was found that direct synthesis from oxide and iodide precursors was possible using hot isostatic pressing (HIPing). Increasing overpressure during HIPing was found to improve the density of the final product. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses indicated that the use of AgI as the source of iodine affected the formation of the target iodovanadinite phase and produced unfavourable phase assemblages. Here, we report the direct synthesis of Pb₅(VO₄)₃I in a single step by hot isostatic pressing. Full article

(This article belongs to the Special Issue Advances in Ceramics, 2nd Edition)

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27 pages, 4581 KiB

Open AccessReview

Nutrient-Doped Hydroxyapatite: Structure, Synthesis and Properties

by Mohamed Ammar, Sherif Ashraf and Jonas Baltrusaitis

Ceramics 2023, 6(3), 1799-1825; https://doi.org/10.3390/ceramics6030110 - 22 Aug 2023

Cited by 8 | Viewed by 3289

Abstract

Complex inorganic powders based on calcium phosphates have found a plethora of practical applications. Of particular interest are the CaO-P₂O₅ system-based multi-component material powders and granules as the source of major- and micronutrients for the plants. The emerging strategy is [...] Read more.

Complex inorganic powders based on calcium phosphates have found a plethora of practical applications. Of particular interest are the CaO-P₂O₅ system-based multi-component material powders and granules as the source of major- and micronutrients for the plants. The emerging strategy is to use nano fertilizers based on hydroxyapatite (HAP) for phosphorus and other nutrient delivery. The doping of micronutrients into HAP structure presents an interesting challenge in obtaining specific phase compositions of these calcium phosphates. Various techniques, including mechanochemical synthesis, have been employed to fabricate doped HAP. Mechanochemical synthesis is of particular interest in this review since it presents a relatively simple, scalable, and cost-effective method of calcium phosphate powder processing. The method involves the use of mechanical force to promote chemical reactions and create nanometric powders. This technique has been successfully applied to produce HAP nanoparticles alone, and HAP doped with other elements, such as zinc and magnesium. Nanofertilizers developed through mechanochemical synthesis can offer several advantages over conventional fertilizers. Their nanoscale size allows for rapid absorption and controlled release of nutrients, which leads to improved nutrient uptake efficiency by plants. Furthermore, the tailored properties of HAP-based nano fertilizers, such as controlled porosity and degradation levels, contribute to their effectiveness in providing plant nutrition. Full article

(This article belongs to the Special Issue Innovative Research on Calcium Phosphates Based Ceramics)

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11 pages, 1370 KiB

Open AccessArticle

Influence of Alkali Metal Ions on the Structural and Spectroscopic Properties of Sm³⁺-Doped Silicate Glasses

by Israel R. Montoya Matos

Ceramics 2023, 6(3), 1788-1798; https://doi.org/10.3390/ceramics6030109 - 21 Aug 2023

Cited by 2 | Viewed by 2090

Abstract

In the present work, the influence of alkali ions (Li, Na, K) on the structural and spectroscopic properties of silica glasses doped with Sm³⁺ was investigated. Infrared and Raman spectroscopy techniques were used to investigate the structural properties of the alkali silicate [...] Read more.

In the present work, the influence of alkali ions (Li, Na, K) on the structural and spectroscopic properties of silica glasses doped with Sm³⁺ was investigated. Infrared and Raman spectroscopy techniques were used to investigate the structural properties of the alkali silicate glasses. The optical absorption showed bands characteristic of Sm³⁺ ions in alkali silicate glasses, and this was investigated. The Judd–Ofelt theory was applied to evaluate the phenomenological intensity parameters (Ω₂, Ω₄, and Ω₆) of the optical absorption measurements. The multi-channel visible and near infrared emission transitions originating from the ⁴G_5/2-emitting state of the Sm³⁺ in alkali silicate glasses with a maximum phonon energy of ~1050 cm⁻¹ were investigated. From the evaluated Judd–Ofelt parameters, radiative parameters such as spontaneous emission probabilities, radiative lifetimes, branching ratios, and stimulated emission cross-sections were calculated. The recorded luminescence spectra regions revealed intense green, orange, red, and near-infrared emission bands, providing new traces for developing tunable laser and optoelectronic devices. Full article

(This article belongs to the Special Issue Advanced Glasses and Glass-Ceramics)

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23 pages, 3961 KiB

Open AccessArticle

Alkali-Activated Brick Aggregates as Industrial Valorized Wastes: Synthesis and Properties

by Abdel Boughriet, Oscar Allahdin, Nicole Poumaye, Gildas Doyemet, Grégory Tricot, Bertrand Revel, Baghdad Ouddane and Michel Wartel

Ceramics 2023, 6(3), 1765-1787; https://doi.org/10.3390/ceramics6030108 - 14 Aug 2023

Cited by 2 | Viewed by 1883

Abstract

In recent works, many industrial by-products were employed as solid precursors for the synthesis of alkali-activated binders and as alternatives to Portland cement for the immobilization of hazardous, toxic and nuclear wastes. Among industrial wastes, alkali-activated brick was found to be an interesting [...] Read more.

In recent works, many industrial by-products were employed as solid precursors for the synthesis of alkali-activated binders and as alternatives to Portland cement for the immobilization of hazardous, toxic and nuclear wastes. Among industrial wastes, alkali-activated brick was found to be an interesting porous composite for removing very toxic heavy metals (Pb²⁺, Cd²⁺, Co²⁺) and radio-nuclides (Sr²⁺, Cs⁺, Rb⁺) from aqueous solutions. The starting material is very attractive due to the presence of metakaolinite as a geo-polymer precursor and silica for increasing material permeability and facilitating water filtration. The alkaline reaction gave rise to geo-polymerization followed by partial zeolitization. Elemental surface micro-analysis was performed by Scanning Electron Microscopy (SEM) equipped with an Energy-Dispersive X-ray Spectrometer (EDS). The formation of crystalline phases was corroborated by X-ray diffraction (XRD) analysis. Information about ²⁹Si, ²⁷Al and ¹H nuclei environments in crystallized and amorphous aluminosilicates was obtained by ²⁹Si, ²⁷Al and ¹H MAS NMR. ²⁷Al–¹H dipolar-mediated correlations were investigated by employing dipolar hetero-nuclear multiple quantum coherence (D-HMQC) NMR, highlighting Al–O–H bonds in bridging hydroxyl groups (Si–OH–Al) that are at the origin of adsorptive properties. Aqueous structural stability and cationic immobilization characteristics before and after material calcination were investigated from acid-leaching experiments. Full article

(This article belongs to the Special Issue The Production Processes and Applications of Geopolymers)

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16 pages, 490 KiB

Open AccessReview

Geopolymer Antimicrobial and Hydrophobic Modifications: A Review

by Vojtěch Růžek, Jan Novosád and Katarzyna Ewa Buczkowska

Ceramics 2023, 6(3), 1749-1764; https://doi.org/10.3390/ceramics6030107 - 11 Aug 2023

Cited by 7 | Viewed by 3309

Abstract

The article summarizes the state of the art in increasing antimicrobial activity and hydrophobic properties of geopolymer materials. Geopolymers are inorganic polymers formed by polycondensation of aluminosilicate precursors in an alkaline environment and are considered a viable alternative to ordinary Portland cement-based materials, [...] Read more.

The article summarizes the state of the art in increasing antimicrobial activity and hydrophobic properties of geopolymer materials. Geopolymers are inorganic polymers formed by polycondensation of aluminosilicate precursors in an alkaline environment and are considered a viable alternative to ordinary Portland cement-based materials, due to their improved mechanical properties, resistance to chemicals, resistance to high temperature, and lower carbon footprint. Like concrete, they are susceptible to microbially induced deterioration (corrosion), especially in a humid environment, primarily due to surface colonization by sulphur-oxidizing bacteria. This paper reviews various methods for hydrophobic or antimicrobial protection by the method of critical analysis of the literature and the results are discussed, along with potential applications of geopolymers with improved antimicrobial properties. Metal nanoparticles, despite their risks, along with PDMS and epoxy coatings, are the most investigated and effective materials for geopolymer protection. Additionally, future prospects, risks, and challenges for geopolymer research and protection against degradation are presented and discussed. Full article

(This article belongs to the Special Issue The Production Processes and Applications of Geopolymers)

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14 pages, 10405 KiB

Open AccessArticle

Structure and Relaxor Behavior of (0.5 − x)BiFeO₃-0.5PbFe_0.5Nb_0.5O₃-xPbTiO₃ Ternary Ceramics

by Nikita A. Boldyrev, Eugene I. Sitalo, Lidia A. Shilkina, Alexander V. Nazarenko, Andrei D. Ushakov, Vladimir Y. Shur, Larisa A. Reznichenko and Ekaterina V. Glazunova

Ceramics 2023, 6(3), 1735-1748; https://doi.org/10.3390/ceramics6030106 - 8 Aug 2023

Viewed by 1354

Abstract

Ceramics of the quasi-binary concentration section (0.1 ≤ x ≤ 0.2, Δx = 0.025) of the ternary solid solution system (0.5 − x)BiFeO₃-0.5PbFe_0.5Nb_0.5O₃-xPbTiO₃ were prepared by the conventional solid-phase reaction [...] Read more.

Ceramics of the quasi-binary concentration section (0.1 ≤ x ≤ 0.2, Δx = 0.025) of the ternary solid solution system (0.5 − x)BiFeO₃-0.5PbFe_0.5Nb_0.5O₃-xPbTiO₃ were prepared by the conventional solid-phase reaction method. An X-ray study at different temperatures revealed that (0.5 − x)BF-0.5PFN-xPT ceramics have a cluster morphology. Clusters have different modulation, crystal lattice symmetry, and chemical composition. The presence of a cluster structure in a solid solution with heterovalent substitution, consisting of regions rich in Ti⁺⁴, Nb⁺⁵, or Fe³⁺, has led to the appearance of Maxwell–Wagner polarization in the studied ceramics. The study of the dielectric characteristics revealed the relaxor-like behavior of the studied ceramics. The grain morphology, dielectric, pyroelectric, and piezoelectric properties of the selected solid solutions were investigated. The highest piezoelectric coefficient, d₃₃ = 280 pC/N, was obtained in the 0.3BiFeO₃-0.5PbFe_0.5Nb_0.5O₃-0.2PbTiO₃ ceramics. Study of the dielectric characteristics of all samples revealed relaxor ferroelectric behavior and a region of diffuse phase transition from the paraelectric to ferroelectric phase in the temperature range of 140–170 °C. Full article

(This article belongs to the Special Issue Advances in Ferroelectric, Construction, Luminescent Ceramics and Crystals)

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30 pages, 6196 KiB

Open AccessReview

Zirconia-Based Ceramics Reinforced by Carbon Nanotubes: A Review with Emphasis on Mechanical Properties

by Soukaina Lamnini, Diego Pugliese and Francesco Baino

Ceramics 2023, 6(3), 1705-1734; https://doi.org/10.3390/ceramics6030105 - 6 Aug 2023

Cited by 4 | Viewed by 2738

Abstract

This review outlines the state of the art, processing techniques, and mechanical testing methods of zirconia (ZrO₂)-based composites reinforced by carbon nanotubes (CNTs). The use of CNTs as a secondary phase in a zirconia matrix is motivated by their outstanding crack [...] Read more.

This review outlines the state of the art, processing techniques, and mechanical testing methods of zirconia (ZrO₂)-based composites reinforced by carbon nanotubes (CNTs). The use of CNTs as a secondary phase in a zirconia matrix is motivated by their outstanding crack self-healing ability, the possibility to tailor the desired nano-structural properties, and their exceptional wear behavior. Therefore, a detailed investigation into CNT features has been provided. The debate of using the different Vickers indentation fracture toughness equations to estimate the resistance of crack propagation was critically reviewed according to crack characteristics. Finally, this review particularly highlights the exceptional role of ZrO₂-based composites as a promising material owing to their outstanding tribo-mechanical properties. Full article

(This article belongs to the Special Issue Ceramic Processing and Sintering, Volume II)

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23 pages, 4217 KiB

Open AccessReview

Unlocking the Potential of Biomass Fly Ash: Exploring Its Application in Geopolymeric Materials and a Comparative Case Study of BFA-Based Geopolymeric Concrete against Conventional Concrete

by Baturalp Yalcinkaya, Tomas Spirek, Milan Bousa, Petr Louda, Vojtěch Růžek, Cezary Rapiejko and Katarzyna Ewa Buczkowska

Ceramics 2023, 6(3), 1682-1704; https://doi.org/10.3390/ceramics6030104 - 3 Aug 2023

Cited by 6 | Viewed by 2863

Abstract

The production of conventional cement involves high energy consumption and the release of substantial amounts of carbon dioxide (CO₂), exacerbating climate change. Additionally, the extraction of raw materials, such as limestone and clay, leads to habitat destruction and biodiversity loss. Geopolymer [...] Read more.

The production of conventional cement involves high energy consumption and the release of substantial amounts of carbon dioxide (CO₂), exacerbating climate change. Additionally, the extraction of raw materials, such as limestone and clay, leads to habitat destruction and biodiversity loss. Geopolymer technology offers a promising alternative to conventional cement by utilizing industrial byproducts and significantly reducing carbon emissions. This paper analyzes the utilization of biomass fly ash (BFA) in the formation of geopolymer concrete and compares its carbon and cost impacts to those of conventional concrete. The previous analysis shows great potential for geopolymers to reduce the climate change impact of cement production. The results of this analysis indicate a significant disparity in the computed financial and sustainability costs associated with geopolymers. Researchers have shown that geopolymers may help mitigate the effects of cement manufacturing on the environment. These geopolymers are predicted to reduce green gas emissions by 40–80%. They also show that those advantages can be realized with the best possible feedstock source and the cheapest possible conveyance. Furthermore, our case study on CO₂ emission and cost calculation for BFA-based geopolymer and conventional concrete shows that geopolymer concrete preparation emits 56% less CO₂ than conventional concrete while costing 32.4% less per ton. Full article

(This article belongs to the Special Issue The Production Processes and Applications of Geopolymers)

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15 pages, 4431 KiB

Open AccessArticle

Porous Ceramic ZnO Nanopowders: Features of Photoluminescence, Adsorption and Photocatalytic Properties

by Marianna Gavrilova, Diana Gavrilova, Sergey Evstropiev, Andrey Shelemanov and Igor Bagrov

Ceramics 2023, 6(3), 1667-1681; https://doi.org/10.3390/ceramics6030103 - 2 Aug 2023

Cited by 3 | Viewed by 1365

Abstract

The grainy and porous ZnO powders were synthesized by thermal decomposition of zinc nitrate and polymer-salt method. The comparative study of the crystal structure, morphology, luminescence, adsorptive and photocatalytic properties of ZnO powders was carried out. The addition of PVP in initial aqueous [...] Read more.

The grainy and porous ZnO powders were synthesized by thermal decomposition of zinc nitrate and polymer-salt method. The comparative study of the crystal structure, morphology, luminescence, adsorptive and photocatalytic properties of ZnO powders was carried out. The addition of PVP in initial aqueous solutions of zinc nitrate determines the remarkable change of powder morphology and decreases the average size of ZnO nanocrystals. Luminescence spectra in the visible spectral range indicate the significant difference of structural defects types in grainy and porous powders. Porous powders demonstrate high ability for singlet oxygen photogeneration and photocatalytic properties. The kinetics of diazo dye adsorption on both powders is described successfully by the kinetic equation of pseudo-second order. Kinetic dependencies of photocatalytic oxidation of Chicago Sky Blue diazo dye using as grain ZnO powder so as porous ZnO powders are described by the Langmuir–Hinshelwood model but process rates are different. Porous ZnO powder demonstrates strong ability for photogeneration of singlet oxygen under visible irradiation and high photocatalytic properties (rate constant 0.042 min⁻¹). Full article

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12 pages, 4204 KiB

Open AccessArticle

Synthesis and Characterization of Nd:YAG Ceramics for Laser Applications

by Olga Alondra Echartea-Reyes, Gloria Verónica Vázquez, José Adalberto Castillo-Robles, Juan López-Hernández, Carlos Adrián Calles-Arriaga, Wilian Jesús Pech-Rodríguez and Enrique Rocha-Rangel

Ceramics 2023, 6(3), 1655-1666; https://doi.org/10.3390/ceramics6030102 - 2 Aug 2023

Cited by 1 | Viewed by 2424

Abstract

Materials known as Nd:YAG are crystalline materials of the cubic system made from the neodymium-doped yttrium aluminum garnet, which, among others, have excellent optical properties. Nd:YAG four-level laser devices are frequently used in both the health and industrial sectors. In this study, a [...] Read more.

Materials known as Nd:YAG are crystalline materials of the cubic system made from the neodymium-doped yttrium aluminum garnet, which, among others, have excellent optical properties. Nd:YAG four-level laser devices are frequently used in both the health and industrial sectors. In this study, a simple and inexpensive alternative to manufacturing Nd:YAG materials through solid state reactions following powder processing routes was proposed. For this, an intense mixture of the precursor materials (Al₂O₃ and Y₂O₃) was carried out, followed by the addition of neodymium atoms to improve the optical properties of the resulting material. High-energy mechanical mixing of the precursor powders resulted in submicron particles with good size distributions of the powders. The advance of YAG formation was monitored by intermediate phase formation during heat treatment through interrupted tests at different temperatures and analysis by X-ray diffraction. From this analysis, it was found that reaction for the formation of the desired YAG is completed at 1500 °C. Fourier transform infrared spectroscopy analyses determined the presence of functional groups corresponding to the YAG. Finally, the study employing optical emission spectroscopy showed wavelengths in agreement with those of the electronic structure of the elements of the synthesized Nd:YAG. Full article

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9 pages, 1843 KiB

Open AccessArticle

Water-Glass-Assisted Foaming in Foamed Glass Production

by Sonja Smiljanić, Uroš Hribar, Matjaž Spreitzer and Jakob König

Ceramics 2023, 6(3), 1646-1654; https://doi.org/10.3390/ceramics6030101 - 2 Aug 2023

Cited by 1 | Viewed by 1919

Abstract

The energy efficiency of buildings can be greatly improved by decreasing the energy embodied in installed materials. In this contribution, we investigated the possibility of foaming waste bottle glass in the air atmosphere with the addition of water glass, which would reduce the [...] Read more.

The energy efficiency of buildings can be greatly improved by decreasing the energy embodied in installed materials. In this contribution, we investigated the possibility of foaming waste bottle glass in the air atmosphere with the addition of water glass, which would reduce the energy used in the production of foamed glass boards. The results show that with the increased addition of water glass, the crystallinity and the thermal conductivity decrease, however, the remaining crystal content prevents the formation of closed-porous foams. The added water glass only partly protects the carbon from premature oxidation, and the foaming mechanism in the air is different than in the argon atmosphere. The lowest obtained foam density in the air atmosphere is 123 kg m⁻³, while the lowest thermal conductivity is 53 mW m⁻¹ K⁻¹, with an open porosity of 50% for the sample obtained in the air, containing 12 wt% of water glass, 2 wt% of B₂O₃, 2 wt% AlPO₄ and 2 wt% K₃PO₄. Full article

(This article belongs to the Special Issue Advanced Glasses and Glass-Ceramics)

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14 pages, 3828 KiB

Open AccessArticle

Effect of Diamond Phase Dispersion on the Properties of Diamond-SiC-Si Composites

by Sergey P. Bogdanov, Andrey S. Dolgin, Sergey N. Perevislov, Nikolay A. Khristyuk and Maxim M. Sychov

Ceramics 2023, 6(3), 1632-1645; https://doi.org/10.3390/ceramics6030100 - 28 Jul 2023

Viewed by 1424

Abstract

The research aimed at the composition optimization for diamond-SiC-Si composites. The effect of a porous diamond workpiece was studied on the properties (porosity, density, modulus of elasticity, phase composition) of the product of its siliconization with molten silicon. The lowest porosity and highest [...] Read more.

The research aimed at the composition optimization for diamond-SiC-Si composites. The effect of a porous diamond workpiece was studied on the properties (porosity, density, modulus of elasticity, phase composition) of the product of its siliconization with molten silicon. The lowest porosity and highest modulus of elasticity were observed in the case of using mixed matrices with the maximum size of diamond grains of 250/200 μm for siliconization. The best results in terms of the sound speed (16,600 m/s) and elasticity modulus (860 GPa) were achieved by microwave processing of a composite containing detonation nanodiamonds. Full article

(This article belongs to the Special Issue Composite Nanopowders: Synthesis and Applications)

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9 pages, 1534 KiB

Open AccessArticle

Phase Composition and Magnetic Properties of Nanoparticles with Magnetite–Maghemite Structure

by Sergey I. Andronenko, Anton M. Nikolaev, Stanislav M. Suharzhevsky, Alexander A. Sinelnikov, Anastasia S. Kovalenko, Alexandra G. Ivanova and Olga A. Shilova

Ceramics 2023, 6(3), 1623-1631; https://doi.org/10.3390/ceramics6030099 - 18 Jul 2023

Cited by 4 | Viewed by 1778

Abstract

Precipitation of nanopowders with mixed magnetite–maghemite composition was carried out under different conditions and with different separation techniques. The exact character of interactions of different iron oxide phases in the nanopowder was the main object of interest. The obtained nanopowders have spherical particles [...] Read more.

Precipitation of nanopowders with mixed magnetite–maghemite composition was carried out under different conditions and with different separation techniques. The exact character of interactions of different iron oxide phases in the nanopowder was the main object of interest. The obtained nanopowders have spherical particles about 10–20 nm in size. Electron paramagnetic resonance (EPR) study showed that iron ions incorporate fully into magnetite and maghemite structures. The shape of the EPR line points out that single homogenous solid solutions were formed during synthesis. In the studied solid solutions, different ratios of vacancies and Fe²⁺/Fe³⁺ ratios were observed but in spite of different synthesis techniques in both cases, there were no additional diamagnetic structural phases presented. Full article

(This article belongs to the Special Issue Composite Nanopowders: Synthesis and Applications)

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50 pages, 8002 KiB

Open AccessReview

Zirconolite Matrices for the Immobilization of REE–Actinide Wastes

by Sergey V. Yudintsev, Maximilian S. Nickolsky, Michael I. Ojovan, Olga I. Stefanovsky, Victor I. Malkovsky, Amina S. Ulanova and Lewis R. Blackburn

Ceramics 2023, 6(3), 1573-1622; https://doi.org/10.3390/ceramics6030098 - 15 Jul 2023

Cited by 6 | Viewed by 2148

Abstract

The structural and chemical properties of zirconolite (ideally CaZrTi₂O₇) as a host phase for separated REE–actinide-rich wastes are considered. Detailed analysis of both natural and synthetic zirconolite-structured phases confirms that a selection of zirconolite polytype structures may be obtained, [...] Read more.

The structural and chemical properties of zirconolite (ideally CaZrTi₂O₇) as a host phase for separated REE–actinide-rich wastes are considered. Detailed analysis of both natural and synthetic zirconolite-structured phases confirms that a selection of zirconolite polytype structures may be obtained, determined by the provenance, crystal chemistry, and/or synthesis route. The production of zirconolite ceramic and glass–ceramic composites at an industrial scale appears most feasible by cold pressing and sintering (CPS), pressure-assisted sintering techniques such as hot isostatic pressing (HIP), or a melt crystallization route. Moreover, we discuss the synthesis of zirconolite glass ceramics by the crystallization of B–Si–Ca–Zr–Ti glasses containing actinides in conditions of increased temperatures relevant to deep borehole disposal (DBD). Full article

(This article belongs to the Special Issue Zirconolite Ceramic and Glass-Ceramic Wasteforms)

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14 pages, 6764 KiB

Open AccessArticle

Bismuth-Germanate Glasses: Synthesis, Structure, Luminescence, and Crystallization

by Ksenia Serkina, Irina Stepanova, Aleksandr Pynenkov, Maria Uslamina, Konstantin Nishchev, Kirill Boldyrev, Roman Avetisov and Igor Avetissov

Ceramics 2023, 6(3), 1559-1572; https://doi.org/10.3390/ceramics6030097 - 13 Jul 2023

Cited by 2 | Viewed by 2368

Abstract

Bismuth-germanate glasses, which are well known as a promising active medium for broadband near-infrared spectral range fiber lasers and as an initial matrix for nonlinear optical glass ceramics, have been synthesized in a 5–50 mol% Bi₂O₃ wide concentration range. Their [...] Read more.

Bismuth-germanate glasses, which are well known as a promising active medium for broadband near-infrared spectral range fiber lasers and as an initial matrix for nonlinear optical glass ceramics, have been synthesized in a 5–50 mol% Bi₂O₃ wide concentration range. Their structural and physical characteristics were studied by Raman and FT-IR spectroscopy, differential scanning calorimetry, X-ray diffraction, optical, and luminescence methods. It has been found that the main structural units of glasses are [BiO₆] and [GeO₄]. The growth in bismuth oxide content resulted in an increase in density and refractive index. The spectral and luminescent properties of glasses strongly depended on the amount of bismuth active centers. The maximum intensity of IR luminescence has been achieved for the 5Bi₂O₃-95GeO₂ sample. The heat treatment of glasses resulted in the formation of several crystalline phases, the structure and amount of which depended on the initial glass composition. The main phases were non-linear Bi₂GeO₅ and scintillating Bi₄Ge₃O₁₂. Comparing with the previous papers dealing with bismuth and germanium oxide-based glasses, we enlarge the range of Bi₂O₃ concentration up to 50 mol% and decrease the synthesis temperature from 1300 to 1100 °C. Full article

(This article belongs to the Special Issue Advanced Glasses and Glass-Ceramics)

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13 pages, 31560 KiB

Open AccessArticle

Formation and Photophysical Properties of Silver Clusters in Bulk of Photo-Thermo-Refractive Glass

by Leonid Yu. Mironov, Dmitriy V. Marasanov, Mariia D. Sannikova, Ksenia S. Zyryanova, Artem A. Slobozhaninov and Ilya E. Kolesnikov

Ceramics 2023, 6(3), 1546-1558; https://doi.org/10.3390/ceramics6030096 - 13 Jul 2023

Cited by 1 | Viewed by 1665

Abstract

The bright luminescence of silver clusters in glass have potential applications in solid-state lighting, optical memory, and spectral converters. In this work, luminescent silver clusters were formed in the bulk of photo-thermo-refractive glass (15Na₂O-5ZnO-2.9Al₂O₃-70.3SiO₂-6.5F, mol.%) [...] Read more.

The bright luminescence of silver clusters in glass have potential applications in solid-state lighting, optical memory, and spectral converters. In this work, luminescent silver clusters were formed in the bulk of photo-thermo-refractive glass (15Na₂O-5ZnO-2.9Al₂O₃-70.3SiO₂-6.5F, mol.%) doped with different Ag₂O concentrations from 0.01 to 0.05 mol.%. The spontaneous formation of plasmonic nanoparticles during glass synthesis was observed at 0.05 mol.% of Ag₂O in the glass composition, limiting the silver concentration range for cluster formation. The luminescence of silver clusters was characterized by steady-state and time-resolved spectroscopy techniques. The rate constants of fluorescence, phosphorescence, intersystem crossing, and nonradiative deactivation were estimated on the basis of an experimental study. A comparison of the results obtained for the photophysical properties of luminescent silver clusters formed in the ion-exchanged layers of photo-thermo-refractive glass is provided. Full article

(This article belongs to the Special Issue Advanced Glasses and Glass-Ceramics)

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15 pages, 3404 KiB

Open AccessArticle

Magnesium Oxide Powder Synthesis in Cathodic Arc Discharge Plasma in an Argon Environment at Atmospheric Pressure

by Dmitry Sorokin, Konstantin Savkin, Dmitry Beloplotov, Viktor Semin, Andrey Kazakov, Alisa Nikonenko, Alexander Cherkasov and Konstantin Shcheglov

Ceramics 2023, 6(3), 1531-1545; https://doi.org/10.3390/ceramics6030095 - 11 Jul 2023

Cited by 1 | Viewed by 1501

Abstract

Discharges with cathode spots can operate in a wide range of gas pressures. Erosion of the cathode material is an inherent property of such discharges. The erosion products are considered to be ionized atoms and electrically neutral microdroplets. In accordance with this concept, [...] Read more.

Discharges with cathode spots can operate in a wide range of gas pressures. Erosion of the cathode material is an inherent property of such discharges. The erosion products are considered to be ionized atoms and electrically neutral microdroplets. In accordance with this concept, a plasma source based on a pulsed cathodic arc discharge in atmospheric-pressure argon with a current of up to 200 A, a pulse duration of 250 μs, and a pulse repetition rate of 10 Hz was implemented. Using this source, the synthesis of magnesium oxide powder was performed. The chemical composition of the erosion products was determined using the TEM/EDS method and the composition of the gas mixture in which the discharge system operated was evaluated by optical spectrometry. It was shown that particles of the synthesized powder have different morphological features, depending on the nature of the electrical erosion of the cathode material. Micron-sized particles are formed due to the removal of microdroplets from liquid–metal craters on the cathode surface at certain plasma pressures. Submicron particles are produced during the agglomeration of atoms originating from the plasma jets flowing out from cathode spots. These atoms are magnesium ions that are neutralized by collisions with gas particles. The advantages and disadvantages of this synthesis method are discussed in this paper. The reference methods for the powder synthesis of magnesium oxide are compared. The prospects of the studied method from the point of view of its application for obtaining ceramic materials are also evaluated. Full article

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14 pages, 2332 KiB

Open AccessReview

A Review of Cr²⁺ or Fe²⁺ Ion-Doped Zinc Sulfide and Zinc Selenide Ceramics as IR Laser Active Media

by Natalia Timofeeva, Stanislav Balabanov and Jiang Li

Ceramics 2023, 6(3), 1517-1530; https://doi.org/10.3390/ceramics6030094 - 11 Jul 2023

Cited by 6 | Viewed by 1880

Abstract

Zinc chalcogenides doped with Cr²⁺ or Fe²⁺ ions are of considerable interest as active media for IR lasers operating in the 2–5 µm wavelength range. Such lasers are in demand in various fields of medicine, remote sensing and atmospheric monitoring, ranging, [...] Read more.

Zinc chalcogenides doped with Cr²⁺ or Fe²⁺ ions are of considerable interest as active media for IR lasers operating in the 2–5 µm wavelength range. Such lasers are in demand in various fields of medicine, remote sensing and atmospheric monitoring, ranging, optical communication systems, and military applications. In recent years, however, the rate of improvement in the characteristics of zinc chalcogenide laser sources has slowed considerably. Unwanted thermally induced effects, parasitic oscillations, and laser-induced damage of the active element have hindered the scaling of output power and efficiency. However, the physical and chemical properties of the materials leave ample room for further improvements. In particular, the control of the dopant concentration profile in the active element is of great importance. Zero concentration of Cr²⁺ or Fe²⁺ ions on the radiation input/output surfaces can significantly increase the laser-induced damage threshold; the designed concentration distribution in the element volume allows regulation of heat dissipation and reduction of parasitic oscillations. The zinc chalcogenide ceramic technology seems to be the most suitable to solve this challenge. This review presents and discusses the state of the art in ZnS and ZnSe optical and laser ceramics and the directions for further development of their technology. Full article

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9 pages, 1446 KiB

Open AccessArticle

A Study of PbF₂ Nanoparticles Crystallization Mechanism in Mixed Oxyde-Fluoride Glasses

by Saule Dyussembekova, Ekaterina Trusova, Sergey Kichanov, Kiril Podbolotov and Denis Kozlenko

Ceramics 2023, 6(3), 1508-1516; https://doi.org/10.3390/ceramics6030093 - 11 Jul 2023

Cited by 2 | Viewed by 1361

Abstract

Samples of nanocrystalline PbF₂ glass ceramics were obtained by heat-treating SiO₂–GeO₂–PbO–PbF₂–CdF₂ glasses. The Ho₂O₃ and Tm₂O₃ doping effects on the structural features of PbF₂ nanoparticles were studied using [...] Read more.

Samples of nanocrystalline PbF₂ glass ceramics were obtained by heat-treating SiO₂–GeO₂–PbO–PbF₂–CdF₂ glasses. The Ho₂O₃ and Tm₂O₃ doping effects on the structural features of PbF₂ nanoparticles were studied using small-angle X-ray scattering and X-ray diffraction methods. The enlargements of the average sizes of nanoparticles and the sizes of local areas of density fluctuations have been found to be correlated with an increase in concentrations of Ho₂O₃ and Tm₂O₃ in initial glasses. A variation in the concentrations of Ho₂O₃ and Tm₂O₃ does not affect the morphology and fractal dimension of the formed PbF₂ nanoparticles. Full article

(This article belongs to the Special Issue Advanced Glasses and Glass-Ceramics)

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18 pages, 4448 KiB

Open AccessArticle

Phase Transformations upon Formation of Transparent Lithium Alumosilicate Glass-Ceramics Nucleated by Yttrium Niobates

by Olga Dymshits, Anastasia Bachina, Irina Alekseeva, Valery Golubkov, Marina Tsenter, Svetlana Zapalova, Kirill Bogdanov, Dmitry Danilovich and Alexander Zhilin

Ceramics 2023, 6(3), 1490-1507; https://doi.org/10.3390/ceramics6030092 - 6 Jul 2023

Cited by 1 | Viewed by 1680

Abstract

Phase transformations in the lithium aluminosilicate glass nucleated by a mixture of yttrium and niobium oxides and doped with cobalt ions were studied for the development of multifunctional transparent glass-ceramics. Initial glass and glass-ceramics obtained by isothermal heat-treatments at 700–900 °C contain YNbO [...] Read more.

Phase transformations in the lithium aluminosilicate glass nucleated by a mixture of yttrium and niobium oxides and doped with cobalt ions were studied for the development of multifunctional transparent glass-ceramics. Initial glass and glass-ceramics obtained by isothermal heat-treatments at 700–900 °C contain YNbO₄ nanocrystals with the distorted tetragonal structure. In samples heated at 1000 °C and above, the monoclinic features are observed. High-temperature X-ray diffraction technique clarifies the mechanism of the monoclinic yttrium orthoniobate formation, which occurs not upon high-temperature heat-treatments above 900 °C but at cooling the glass-ceramics after such heat-treatments, when YNbO₄ nanocrystals with tetragonal structure undergo the second-order transformation at ~550 °C. Lithium aluminosilicate solid solutions (ss) with β-quartz structure are the main crystalline phase of glass-ceramics prepared in the temperature range of 800–1000 °C. These structural transformations are confirmed by Raman spectroscopy and illustrated by SEM study. The absorption spectrum of the material changes only with crystallization of the β-quartz ss due to entering the Co²⁺ ions into this phase mainly in octahedral coordination, substituting for Li⁺ ions. At the crystallization temperature of 1000 °C, the Co²⁺ coordination in the β-quartz solid solutions changes to tetrahedral one. Transparent glass-ceramics have a thermal expansion coefficient of about 10 × 10⁻⁷ K⁻¹. Full article

(This article belongs to the Special Issue Advanced Glasses and Glass-Ceramics)

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12 pages, 8304 KiB

Open AccessArticle

Effect of a Phosphorus Additive on Luminescent and Scintillation Properties of Ceramics GYAGG:Ce

by Lydia V. Ermakova, Valentina G. Smyslova, Valery V. Dubov, Daria E. Kuznetsova, Maria S. Malozovskaya, Rasim R. Saifutyarov, Petr V. Karpyuk, Petr S. Sokolov, Ilia Yu. Komendo, Aliaksei G. Bondarau, Vitaly A. Mechinsky and Mikhail V. Korzhik

Ceramics 2023, 6(3), 1478-1489; https://doi.org/10.3390/ceramics6030091 - 6 Jul 2023

Cited by 2 | Viewed by 1774

Abstract

The production of scintillating ceramics can require the utilization of the phosphorus compounds at certain stages of 3D-printing, such as vat polymerization, applied for the formation of green bodies before sintering. The effect of phosphorus additive on the microstructure, optical, and scintillation parameters [...] Read more.

The production of scintillating ceramics can require the utilization of the phosphorus compounds at certain stages of 3D-printing, such as vat polymerization, applied for the formation of green bodies before sintering. The effect of phosphorus additive on the microstructure, optical, and scintillation parameters of Gd₁.₄₉₄Y₁.₄₉₄ Ce₀.₀₁₂Al₂Ga₃O₁₂ (GYAGG:Ce) ceramics obtained by pressureless sintering at 1650 °C in an oxygen atmosphere was investigated for the first time. Phosphorus was introduced in the form of NH₄H₂PO₄ into the initial hydroxycarbonate precipitate in a wide concentration range (from 0 to 0.6 wt.%). With increasing of phosphorus concentration, the density and the optical transmittance of garnet ceramics show a decrease, which is caused by an increase in the number of pores and inclusions. The light yield of fast scintillation, which is caused by Ce³⁺ ions, was found to be affected by the phosphorus additive as well. Moreover, an increase in phosphorescence intensity was recognized. Full article

(This article belongs to the Special Issue Advanced Glasses and Glass-Ceramics)

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11 pages, 3837 KiB

Open AccessArticle

Magnesium Oxide and Magnesium Fluoride Nanopowders Produced in a Diffuse Nanosecond Discharge in Argon

by Dmitry Beloplotov, Konstantin Savkin, Viktor Semin and Dmitry Sorokin

Ceramics 2023, 6(3), 1467-1477; https://doi.org/10.3390/ceramics6030090 - 6 Jul 2023

Viewed by 1469

Abstract

The synthesis of the nanopowders of magnesium oxide and magnesium fluoride during the operation of a repetitive diffuse nanosecond discharge in argon at various pressures was performed. Nanosecond voltage pulses with an amplitude of −70 kV, a rise time of 0.7 ns, and [...] Read more.

The synthesis of the nanopowders of magnesium oxide and magnesium fluoride during the operation of a repetitive diffuse nanosecond discharge in argon at various pressures was performed. Nanosecond voltage pulses with an amplitude of −70 kV, a rise time of 0.7 ns, and a duration of 0.7 ns were applied across a point-to-plane gap of 2 mm in length. The pulse repetition rate was 60 Hz. The high-voltage pointed electrode was made of magnesium. A diffuse discharge cold plasma was formed under these conditions. Nanoparticles were produced as a result of an explosion of microprotrusions on the surface of the magnesium electrode duo to a high current density. Lines of magnesium atoms and ions were observed in the emission optical spectrum. Under the actions of the gas dynamics processes caused by the plasma channel expansion during the interpulse period, nanoparticles were deposited onto the surface of the grounded plane electrode and the side wall of the gas discharge chamber. The morphology, elemental, and phase composition of the powders were studied using transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDS). Full article

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18 pages, 6778 KiB

Open AccessArticle

Optimizing Building Thermal Insulation: The Impact of Brick Geometry and Thermal Coefficient on Energy Efficiency and Comfort

by Ioannis Makrygiannis and Konstantinos Karalis

Ceramics 2023, 6(3), 1449-1466; https://doi.org/10.3390/ceramics6030089 - 5 Jul 2023

Cited by 5 | Viewed by 7196

Abstract

The thermal insulation properties of building walls are critical to the overall energy efficiency and comfort of a building. One important factor that can affect these properties is the type of bricks used in construction. Bricks can vary in their geometry and thermal [...] Read more.

The thermal insulation properties of building walls are critical to the overall energy efficiency and comfort of a building. One important factor that can affect these properties is the type of bricks used in construction. Bricks can vary in their geometry and thermal coefficient, which can impact their ability to transfer heat through the wall. The geometry of a brick can affect its thermal properties by altering the amount of air trapped within it and the surface area available for heat transfer. Hollow bricks or those with complex geometries may have lower thermal conductivity than regular solid bricks due to the air pockets trapped within them. Conversely, larger surface areas on the exterior of the brick can increase heat transfer. The thermal coefficient of clay, a common material used in brick production, is another important factor. Clay has relatively low thermal conductivity, meaning it is a poor conductor of heat. However, the quality of the clay, as well as the firing temperature and duration used in brick production, can impact its thermal coefficient. Higher firing temperatures and longer firing times can result in a more compact and dense clay brick, which can improve its thermal properties. In summary, the thermal insulation properties of building walls can be significantly affected by the type of bricks used in their construction. It is important to consider the geometry and thermal coefficient of the bricks when designing a building to achieve the desired level of thermal insulation. By selecting bricks with appropriate properties, designers can help to improve the energy efficiency and comfort of the building while reducing its environmental impact. Full article

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15 pages, 7862 KiB

Open AccessArticle

Materials in the CaO-K₂O-SO₃-H₂O System Based on Powder Mixtures including Calciolangbeinite K₂Ca₂(SO₄)₃ and Calcium Sulfate Anhydrite CaSO₄

by Alexander I. Kuznetsov, Tatiana V. Safronova, Tatiana B. Shatalova, Yaroslav Y. Filippov, Leonid A. Vaymugin, Vyacheslav S. Vlasenko and Maxim S. Likhanov

Ceramics 2023, 6(3), 1434-1448; https://doi.org/10.3390/ceramics6030088 - 5 Jul 2023

Cited by 1 | Viewed by 1758

Abstract

Materials (cement stone samples) in the CaO-K₂O-SO₃-H₂O system with the target phase compositions, including syngenite K₂Ca(SO₄)₂·H₂O and calcium sulfate dihydrate CaSO₄·2H₂O, were prepared from powder [...] Read more.

Materials (cement stone samples) in the CaO-K₂O-SO₃-H₂O system with the target phase compositions, including syngenite K₂Ca(SO₄)₂·H₂O and calcium sulfate dihydrate CaSO₄·2H₂O, were prepared from powder mixtures of calcium sulfate anhydrite CaSO₄, and/or calciolangbeinite K₂Ca₂(SO₄)₃, and potassium sulfate K₂SO₄ via hydration reactions at a water/powder ratio within an interval of 0.5–0.9. It was revealed that samples with contents of 25, 50, 75 and 100 mol% of syngenite K₂Ca(SO₄)₂·H₂O demonstrated a nonlinear dependence of their respective microstructures on their phase compositions. The microstructures of samples with phase compositions of 25 and 75 mol% of syngenite K₂Ca(SO₄)₂·H₂O consisted of pillar crystals. The microstructures of samples with phase compositions of 50 and 100 mol% of syngenite K₂Ca(SO₄)₂·H₂O consisted of plate crystals. An explanation of microstructure formation was set forth, taking into account equilibria of the dissolution–crystallization processes during cement stone formation. Materials obtained in the CaO-K₂O-SO₃-H₂O system consisting of biocompatible and resorbable (soluble in water) phases can be recommended for testing as potential substances for bone defect treatments. Full article

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Ceramics, Volume 6, Issue 3 (September 2023) – 38 articles

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