Similar Journals
|
Ceramics
Number of Followers: 0  Open Access journalISSN (Online) 2571-6131 Published by MDPI  [258 journals]
|
- Ceramics, Vol. 7, Pages 840-857:
0.98(K0.5Na0.5)NbO3–0.02(Bi0.5Na0.5)(Zr0.85Sn0.15)O3 Single Crystals
Grown by the Seed-Free Solid-State Crystal Growth Method and Their
Characterization
Authors: Eugenie Uwiragiye, Thuy Linh Pham, Jong-Sook Lee, Byoung-Wan Lee, Jae-Hyeon Ko, John G. Fisher
First page: 840
Abstract: (K0.5Na0.5)NbO3-based single crystals are of interest as high-performance lead-free piezoelectric materials, but conventional crystal growth methods have some disadvantages such as the requirement for expensive Pt crucibles and difficulty in controlling the composition of the crystals. Recently, (K0.5Na0.5)NbO3-based single crystals have been grown by the seed-free solid-state crystal growth method, which can avoid these problems. In the present work, 0.98(K0.5Na0.5)NbO3–0.02(Bi0.5Na0.5)(Zr0.85Sn0.15)O3 single crystals were grown by the seed-free solid-state crystal growth method. Sintering aids of 0.15 mol% Li2CO3 and 0.15 mol% Bi2O3 were added to promote single crystal growth. Pellets were sintered at 1150 °C for 15–50 h. Single crystals started to appear from 20 h. The single crystals grown for 50 h were studied in detail. Single crystal microstructure was studied by scanning electron microscopy of the as-grown surface and cross-section of the sample and revealed porosity in the crystals. Electron probe microanalysis indicated a slight reduction in K and Na content of a single crystal as compared to the nominal composition. X-ray diffraction shows that the single crystals contain mixed orthorhombic and tetragonal phases at room temperature. Raman scattering and impedance spectroscopy at different temperatures observed rhombohedral–orthorhombic, orthorhombic–tetragonal and tetragonal–cubic phase transitions. Polarization–electric field (P–E) hysteresis loops show that the single crystal is a normal ferroelectric material with a remanent polarization (Pr) of 18.5 μC/cm2 and a coercive electrical field (Ec) of 10.7 kV/cm. A single crystal presents d33 = 362 pC/N as measured by a d33 meter. Such a single crystal with a large d33 and high Curie temperature (~370 °C) can be a promising candidate for piezoelectric devices.
Citation: Ceramics
PubDate: 2024-06-21
DOI: 10.3390/ceramics7030055
Issue No: Vol. 7, No. 3 (2024)
- Ceramics, Vol. 7, Pages 858-872: Effect of Sodium Oxide on Structure of
Lanthanum Aluminosilicate Glass
Authors: Assia Mabrouk, Ahmed Bachar, Yann Vaills, Aurélien Canizarès, Stuart Hampshire
First page: 858
Abstract: Rare earth (RE) aluminosilicate glasses exhibit several favorable chemical, mechanical and thermal properties. As such, they are considered to be model systems for long-half-life actinides and are candidate containment materials for long-term immobilization of radioactive wastes. The aim of the present study was to investigate the effect of the substitution of sodium oxide on the glass transition temperature and structure of lanthanum aluminosilicate glasses. The primary objective was to elucidate the relationship between the substitution of Na2O for La2O3 on the Tg reduction and structural characteristics of lanthanum aluminosilicate glass, including identifying changes in the main Qn species and local environments of Si and Al. The structure of SiO2–Al2O3–La2O3–Na2O glasses has not been studied previously, and, thus, this investigation is the first to assess the structural changes occurring when La2O3 is substituted by Na2O. Three glasses were prepared with general composition (mol.%): 55SiO2–25Al2O3–20M2On (M = La or Na; n = 3 or 1). Glass G1 contains 20 mol.% La2O3; in G2, 15 mol.% of La2O3 was substituted by 15 mol.% Na2O; and Glass G3 contains 20 mol.% Na2O. The glasses were characterized by DSC to determine glass transition temperatures. As expected, as Na is substituted for La, Tg decreases substantially. Structural studies were carried out by FTIR spectroscopy, 29Si, and 27Al MAS NMR. As Na is substituted for La in these aluminosilicate glasses, the main goals that were achieved were the identification of Qn species and also changes in the local environments of Si and Al: {QnSi(mAl)} and {QnAl(mSi)}.
Citation: Ceramics
PubDate: 2024-06-22
DOI: 10.3390/ceramics7030056
Issue No: Vol. 7, No. 3 (2024)
- Ceramics, Vol. 7, Pages 873-892: The Mechanical Properties of Geopolymers
as a Function of Their Shaping and Curing Parameters
Authors: Camille Zoude, Elodie Prud’homme, Kévyn Johannes, Laurent Gremillard
First page: 873
Abstract: This study investigates the impact of curing conditions, porosity and shaping techniques on the mechanical properties of metakaolin-based geopolymers. Geopolymers offer versatility in shaping, including 3D printing, yet the influence of curing conditions after printing on mechanical properties remains unclear. This is assessed by measuring the bending properties of 3D-printed metakaolin-based geopolymer filaments cured under varied humidity and temperature conditions. The influences of porosity and of shaping technique are observed by comparing the compression properties of molded and 3D-printed samples of various porosity. Samples cured at low humidity exhibit unusually high mechanical properties, which decrease when moved from a dry to a humid environment. This behavior may be due to the presence of PEG within the composition and/or to residual stresses due to the too rapid evacuation of water. High humidity is therefore necessary to ensure optimal curing and stable properties. Increasing the curing temperature helps accelerate geopolymerization without significantly compromising mechanical properties. Direct ink writing offers design flexibility and suitable porosity, but the samples appear to exhibit different failure mechanisms than the molded samples. Additional studies are necessary to understand the interactions between PEG and the geopolymer as well as to better identify the fracture mechanisms within the different samples.
Citation: Ceramics
PubDate: 2024-06-25
DOI: 10.3390/ceramics7030057
Issue No: Vol. 7, No. 3 (2024)
- Ceramics, Vol. 7, Pages 893-905: Properties of a Pressureless Sintered
2Y-TZP Material Combining High Strength and Toughness
Authors: Frank Kern, Bettina Osswald
First page: 893
Abstract: Yttria stabilized zirconia materials are frequently used in mechanical engineering and biomedical applications. Demanding loading conditions require materials combining a high level of strength and fracture toughness. A ready-to-press alumina doped 2 mol% yttria-stabilized zirconia powder was shaped by axial pressing and sintering in air at 1250–1500 °C for 2 h. At 1350 °C the best combination of strength (1450 MPa) and toughness (7.8 MPa√m) was achieved. Materials sintered in the middle of the chosen temperature range combine full density, high transformability and small grain size. Toughness measurements by direct crack length measurements delivered unrealistically high fracture toughness values.
Citation: Ceramics
PubDate: 2024-06-28
DOI: 10.3390/ceramics7030058
Issue No: Vol. 7, No. 3 (2024)
- Ceramics, Vol. 7, Pages 906-925: Computational Investigation of the
Influencing Parameters on the Solidification of Thermoplastic Beryllium
Oxide Slurry in a Cylindrical Shell
Authors: Zamira Sattinova, Bakytzhan Assilbekov, Tassybek Bekenov, Gaukhar Ramazanova
First page: 906
Abstract: This article presents a computational study of the influencing parameters on the solidification of the thermoplastic beryllium oxide slurry in an annular forming cavity. The main purpose of this paper is to study the effect of cooling and casting conditions on the solidification of the BeO suspension by considering the temperature-dependent rheological and physical properties. The results of calculations of the Bingham–Papanastasiou rheological model with experimental data in the intervals of phase transitions with different casting rates of beryllium ceramics have been validated. The use of the regularization parameter made it possible to approximate the flow of the slurry at all levels of its shear rates as highly viscous, followed by a continuous transition to a solid state. The speed of heat removal from the molding during the solidification period is determined by the speed of movement of the slurry and the temperature field on which the width of the transition region depends. The process of solidification of the slurry mass has been evaluated by changing its heat flow distribution and density along the length of the concentric channel. The obtained model calculation results make it possible to control the casting process and eventually realize a uniform structure of castings.
Citation: Ceramics
PubDate: 2024-07-01
DOI: 10.3390/ceramics7030059
Issue No: Vol. 7, No. 3 (2024)
- Ceramics, Vol. 7, Pages 926-943: 2D/2D Heterojunctions of Layered TiO2 and
(NH4)2V3O8 for Sunlight-Driven Methylene Blue Degradation
Authors: Juan Aliaga, Matías Alegria, J. Pedro Donoso, Claudio J. Magon, Igor D. A. Silva, Harold Lozano, Elies Molins, Eglantina Benavente, Guillermo González
First page: 926
Abstract: Photocatalysis based on titanium dioxide (TiO2) has become a promising method to remediate industrial and municipal effluents in an environmentally friendly manner. However, the efficiency of TiO2 is hampered by problems such as rapid electron–hole recombination and limited solar spectrum absorption. Furthermore, the sensitization of TiO2 through heterojunctions with other materials has gained attention. Vanadium, specifically in the form of ammonium vanadate ((NH4)2V3O8), has shown promise as a photocatalyst due to its ability to effectively absorb visible light. However, its use in photocatalysis remains limited. Herein, we present a novel synthesis method to produce lamellar (NH4)2V3O8 as a sensitizer in a supramolecular hybrid photocatalyst of TiO2–stearic acid (SA), contributing to a deeper understanding of its structural and magnetic characteristics, expanding the range of visible light absorption, and improving the efficiency of photogenerated electron–hole separation. Materials, such as TiO2–SA and (NH4)2V3O8, were synthesized and characterized. EPR studies of (NH4)2V3O8 demonstrated their orientation-dependent magnetic properties and, from measurements of the angular variation of g-values, suggest that the VO2+ complexes are in axially distorted octahedral sites. The photocatalytic results indicate that the 2D/2D heterojunction layered TiO2/vanadate at a ratio (1:0.050) removed 100% of the methylene blue, used as a model contaminant in this study. The study of the degradation mechanism of methylene blue emphasizes the role of reactive species such as hydroxyl radicals (•OH) and superoxide ions (O2•−). These species are crucial for breaking down contaminant molecules, leading to their degradation. The band alignment between ammonium vanadate ((NH4)2V3O8) and TiO2–SA, shows effective separation and charge transfer processes at their interface. Furthermore, the study confirms the chemical stability and recyclability of the TiO2–SA/(NH4)2V3O8 photocatalyst, demonstrated that it could be used for multiple photocatalytic cycles without a significant loss of activity. This stability, combined with its ability to degrade organic pollutants under solar irradiation, means that the TiO2–SA/(NH4)2V3O8 photocatalyst is a promising candidate for practical environmental remediation applications.
Citation: Ceramics
PubDate: 2024-07-02
DOI: 10.3390/ceramics7030060
Issue No: Vol. 7, No. 3 (2024)
- Ceramics, Vol. 7, Pages 944-957: Pretreatment of Hybrid Ceramics Using Ho:
YAG, Low-Level Laser Therapy Activated Malachite Green, and Non-Thermal
Plasma on Surface Roughness, Bond Strength, and Color Change, SEM and EDX
Analysis
Authors: Fahad Alkhudhairy, Yasser F. AlFawaz
First page: 944
Abstract: The study aimed to assess the effects of different surface conditionings on hybrid ceramics (HBC). Hydrofluoric acid was combined with a silane (HFA+S), low-level laser therapy activated Malachite green (LLLT-MG), Ho: YAG laser, and non-thermal plasma (NTP) as surface conditioning methods for HBC. Eighty-four HBC discs were prepared and divided into four groups according to surface conditioning methods. The total number of samples (n = 21) for each group was further split into two for the non-thermocycling and thermocycling subgroups. After surface treatment, all samples were examined to study the effect of color change and surface roughness. The shear bond strength (SBS) test of HBC was performed on thermo-cycled samples. Statistical analysis using ANOVA with Tukey post hoc was performed to observe any significant difference among tested groups, p > 0.05. The HFA+S and Ho: YAG surface-treated samples showed higher SBS than other surface-treated samples due to higher surface roughness. All surface conditioning methods, except NTP, induced noticeable color change, making them less suitable for aesthetical purposes in clinical settings. Overall, surface conditioning methods are critical in affecting shear bond strength through surface roughness and color change.
Citation: Ceramics
PubDate: 2024-07-09
DOI: 10.3390/ceramics7030061
Issue No: Vol. 7, No. 3 (2024)
- Ceramics, Vol. 7, Pages 958-974: Exploring Enhanced Structural and
Dielectric Properties in Ag-Doped Sr(NiNb)0.5O3 Perovskite Ceramic for
Advanced Energy Storage
Authors: Faouzia Tayari, Majdi Benamara, Madan Lal, Manel Essid, Priyanka Thakur, Deepak Kumar, S. Soreto Teixeira, M. P. F. Graça, Kais Iben Nassar
First page: 958
Abstract: The ceramic Sr(NiNb)0.5O3, incorporating silver doping in the A site, was synthesized using a sol–gel route and subjected to comprehensive analysis through various experimental techniques. X-ray diffraction data analysis indicates a rhombohedral crystal structure. Scanning electron microscopy (SEM) examination reveals densely packed grains with minimal surface porosity. A thorough investigation of electrical properties, encompassing dielectric constant, loss tangent, electrical impedance, modulus, conductivity, etc., was conducted across a wide frequency range (103–106 Hz) and temperature range (260–340 K). This analysis provided valuable insights into structure–property relationships and conduction mechanisms. The discussion highlights the significance of interface effects, space charge polarization, and Maxwell–Wagner dielectric relaxation in achieving the material’s high dielectric constant at low frequencies and elevated temperatures. Examination of temperature dependence through Nyquist plots elucidates the contributions of grain behavior to the material’s resistive and capacitive properties. The dielectric permittivity, dissipation of energy, and electrical characteristics like impedance, modulus and conductivity are notably influenced by the frequency of the applied electric field and temperature. Overall, the material exhibits promising potential for industrial applications such as energy storage, given its intriguing properties.
Citation: Ceramics
PubDate: 2024-07-10
DOI: 10.3390/ceramics7030062
Issue No: Vol. 7, No. 3 (2024)
- Ceramics, Vol. 7, Pages 975-988: Anti-Bacterial and Anti-Inflammatory
Authors: Elisa Torre, Marco Morra, Clara Cassinelli, Giorgio Iviglia
First page: 975
Abstract: Bone loss is a major burden for society and impacts people’s health all over the world. In a changing world looking toward a more conscious use of raw materials, efforts are being made to increasingly consider new promising biomaterials that account for, on one side, the ability to provide specific functional biological activities and, on the other, the feature of being well tolerated. In this regard, the use of phenolic compounds in the field of bone-related bioengineering shows a rising interest in the development of medical solutions aimed at taking advantage of the multiple beneficial properties of these plant molecules. In this work, the anti-bacterial and anti-inflammatory power of a biphasic calcium phosphate synthetic bone filler coated with a mixture of phenolic compounds was investigated by evaluating the minimal inhibitory concentration (MIC) value against Streptococcus mutans and Porphyromonas gingivalis and the expression of genes involved in inflammation and autophagy by real-time reverse transcription polymerase chain reaction (RT-qPCR) on J774a.1 murine macrophage cells. Results show a MIC of 0.8 μg/mL, a neat anti-inflammatory effect, and induction of autophagy key genes compared to a ceramic bone filler. In conclusion, functionalization with a polyphenol-rich extract confers to a ceramic bone filler anti-bacterial and anti-inflammatory properties.
Citation: Ceramics
PubDate: 2024-07-18
DOI: 10.3390/ceramics7030063
Issue No: Vol. 7, No. 3 (2024)
- Ceramics, Vol. 7, Pages 989-1001: Preparation of Polycrystalline Silicon
by Metal-Induced Crystallization of Silicon–Carbon Powder
Authors: Natalia Igorevna Cherkashina, Vyacheslav Ivanovich Pavlenko, Andrey Ivanovich Gorodov, Dar’ya Aleksandrovna Ryzhikh
First page: 989
Abstract: In this study, we successfully obtained crystalline silicon from silica powder using a metal-induced crystallization method. For this purpose, powders were first prepared from organosilicon compounds and finely dispersed aluminum particles, then their metal-induced crystallization was carried out by annealing at the temperature of 570 °C. Powders of organosilicon compounds (tetraethoxysilane and polyethylhydrosiloxane) were prepared by different technological operations in order to determine precisely the presence of carbon in the product. The results showed that the presence of carbon in silica powder affects the production of crystalline silicon. In silica powders containing no carbon, the formation of crystalline substances does not occur at the annealing temperature of 570 °C. The results of this study are of great importance for the production of polycrystalline silicon powders obtained at reduced temperatures.
Citation: Ceramics
PubDate: 2024-07-27
DOI: 10.3390/ceramics7030064
Issue No: Vol. 7, No. 3 (2024)
- Ceramics, Vol. 7, Pages 1002-1013: Energy Storage Performance of
Na0.5Bi0.5TiO3–CaHfO3 Lead-Free Ceramics Regulated by Defect
Engineering
Authors: Zhuo Li, Jing Zhang, Zixuan Wang, Xiaotian Wei, Dingjie Long, Xin Zhao, Yanhui Niu
First page: 1002
Abstract: Over the past decades, Na0.5Bi0.5TiO3 (NBT)-based ceramics have received increasing attention in energy storage applications due to their high power density and relatively large maximum polarization. However, their high remnant polarization (Pr) and low breakdown field strength are detrimental for their practical applications. In this paper, a new solid solution (1−x)Na0.5Bi0.5TiO3–xCaHfO3 (x = 0.04, 0.08, 0.12, 0.16) was constructed by introducing CaHfO3 into NBT, and thus was prepared using a conventional solid-state reaction. With the addition of CaHfO3, the disorder of the structure increased, A-site vacancies formed, and thus oxygen vacancies were suppressed due to the replacement of the Na+ by Ca2+, resulting in the enhanced relaxation behavior and the reduced Pr, the refined grain, and improved breakdown strength. Furthermore, an optimal recoverable energy storage density (Wrec) of 1.2 J/cm3 was achieved in 0.92Na0.5Bi0.5TiO3–0.08CaHfO3 ceramics under the breakdown strength of 140 kV/cm, which is mainly attributed to the resultant defect of Na+ vacancy.
Citation: Ceramics
PubDate: 2024-07-28
DOI: 10.3390/ceramics7030065
Issue No: Vol. 7, No. 3 (2024)
- Ceramics, Vol. 7, Pages 1014-1029: Synthesis of Bulk-Nucleated
Glass–Ceramics and Porous Glass–Ceramic Composites through
Utilization of Fly Ashes
Authors: Hugo R. Fernandes, Oguzhan Gunduz, Dilshat U. Tulyaganov
First page: 1014
Abstract: Coal combustion in power plants for electric power generation produces millions of tons of residues that are generally disposed of in landfills or ponds occupying vast land, resulting in serious environmental pollution. Fly ash (FA) is one of the main solid wastes generated in coal-based thermal power plants, representing the largest fraction of coal combustion residues (65–95%). Unfortunately, the enormous amount of FA residue is utilized only partly, mainly in the cement industry and building materials field. An alternative approach to using FA is its incorporation into ceramic, glass and glass–ceramic production, aligning with circular economy principles and reducing the environmental footprint of both the energy and ceramic sectors. In this review article, the topics of the composition, properties, classification, and utilization of fly ashes from thermal power plants are discussed. The main objective of this work is a critical analysis of the experimental trials directed to the involvement of FA as a raw material in the fabrication of glass–ceramics and porous ceramic composites.
Citation: Ceramics
PubDate: 2024-07-30
DOI: 10.3390/ceramics7030066
Issue No: Vol. 7, No. 3 (2024)
- Ceramics, Vol. 7, Pages 1030-1042: The Direct Cold Sintering of
α-Al2O3 Ceramics in a Pure Water Medium
Authors: Anastasia A. Kholodkova, Maxim V. Kornyushin, Arseniy N. Khrustalev, Levko A. Arbanas, Andrey V. Smirnov, Yurii D. Ivakin
First page: 1030
Abstract: Porous α-Al2O3 ceramics are a highly sought-after material with a multitude of applications; for example, they are used as filters, substrates, biomedicine materials, etc. Despite the availability of raw materials, a challenge associated with this technology is the high energy budget caused by sintering above 1500 °C. For the cold sintering processing (CSP) of ceramics, lowering the α-Al2O3 sintering temperature is one of the most urgent challenges in the background of its rapid development. This paper is the first to demonstrate a solution to this problem using the CSP of α-alumina ceramics in the presence of pure water as a transient liquid. The manufactured materials were examined using XRD analysis; the evolution of their microstructures during CSP was revealed by SEM; and the porosity was evaluated using the Archimedes method. Ceramics with an open porosity up to 36% were produced at 380–450 °C and 220 MPa in 30 min. An increase in the pressure was found to impede α-Al2O3 formation from γ-AlOOH. The development of the microstructure was discussed within the framework of the dissolution–precipitation model and homogenous nucleation. The results of the SEM study pointed to the coalescence of γ-AlOOH grains during CSP.
Citation: Ceramics
PubDate: 2024-07-31
DOI: 10.3390/ceramics7030067
Issue No: Vol. 7, No. 3 (2024)
- Ceramics, Vol. 7, Pages 1043-1052: Excellent Energy Storage and
Photovoltaic Performances in Bi0.45Na0.45Ba0.1TiO3-Based Lead-Free
Ferroelectricity Thin Film
Authors: Jianhua Wu, Tiantian Zhang, Xing Gao, Lei Ning, Yanhua Hu, Xiaojie Lou, Yunying Liu, Ningning Sun, Yong Li
First page: 1043
Abstract: Inorganic dielectric films have attracted extensive attention in the field of microelectronic and electrical devices because of their wide operating temperature range, small size, and easy integration. Here, we designed and prepared eco-friendly (1-x)Bi0.45Na0.45Ba0.1TiO3-xBi(Mg1/3Nb2/3)O3 multifunctional ferroelectric thin films for energy storage and photovoltaic. The results show that Bi(Mg1/3Nb2/3)O3 can effectively improve the energy storage performance. At x = 0.05, the energy storage density and efficiency are as high as 73.1 J/cm3 and 86.2%, respectively, and can operate stably in a wide temperature range. The breakdown field strength of the thin films increased significantly, and the analysis showed that the addition of Bi(Mg1/3Nb2/3)O3 caused a change in the internal conduction mechanism. At the same time, the generation of polar nanoregions increases the relaxation characteristics, thus improving the energy storage properties. In addition, the thin film material also has excellent ferroelectric photovoltaic properties. This work represents a new design paradigm that can serve as an effective strategy for developing advanced multi-functional materials.
Citation: Ceramics
PubDate: 2024-08-01
DOI: 10.3390/ceramics7030068
Issue No: Vol. 7, No. 3 (2024)
- Ceramics, Vol. 7, Pages 436-451: Polymer-Infiltrated Ceramic Network
Produced by Direct Ink Writing: The Effects of Manufacturing Design on
Mechanical Properties
Authors: Junhui Zhang, Paula Pou, Ludmila Hodásová, Mona Yarahmadi, Sergio Elizalde, Jose-Maria Cabrera, Luis Llanes, Elaine Armelin, Gemma Fargas
First page: 436
Abstract: Polymer-infiltrated ceramic network (PICN) materials have gained considerable attention as tooth-restorative materials due to their mechanical compatibility with human teeth, especially with computer-aided design and computer-aided manufacturing (CAD/CAM) technologies. However, the designed geometry affects the mechanical properties of PICN materials. This study aims to study the relationship between manufacturing geometry and mechanical properties. In doing so, zirconia-based PICN materials with different geometries were fabricated using a direct ink-writing process, followed by copolymer infiltration. Comprehensive analyses of the microstructure and structural properties of zirconia scaffolds, as well as PICN materials, were performed. The mechanical properties were assessed through compression testing and digital image correlation analysis. The results revealed that the compression strength of PICN pieces was significantly higher than the respective zirconia scaffolds without polymer infiltration. In addition, two geometries (C-grid 0 and C-grid 45) have the highest mechanical performance.
Citation: Ceramics
PubDate: 2024-03-22
DOI: 10.3390/ceramics7020028
Issue No: Vol. 7, No. 2 (2024)
- Ceramics, Vol. 7, Pages 452-465: Negative Temperature Coefficient
Properties of Natural Clinoptilolite
Authors: Loredana Schiavo, Lucrezia Aversa, Roberto Verucchi, Rachele Castaldo, Gennaro Gentile, Gianfranco Carotenuto
First page: 452
Abstract: Negative temperature coefficient (NTC) materials are usually based on ceramic semiconductors, and electrons are involved in their transport mechanism. A new type of NTC material, adequate for alternating current (AC) applications, is represented by zeolites. Indeed, zeolites are single charge carrier ionic conductors with a temperature-dependent electrical conductivity. In particular, electrical transport in zeolites is due to the monovalent charge-balancing cations, like K+, capable of hopping between negatively charged sites in the aluminosilicate framework. Owing to the highly non-linear electrical behavior of the traditional electronic NTC materials, the possibility to have alternative types of materials, showing linearity in their electrical behavior, is very desirable. Among different zeolites, natural clinoptilolite has been selected for investigating NTC behavior since it is characterized by high zeolite content, a convenient Si/Al atomic ratio, good mechanical strength due to its compact microstructure, and low toxicity. Clinoptilolite has shown a rapid and quite reversible impedance change under heating, characterized by a linear dependence on temperature. X-ray diffraction (XRD) has been used to identify the natural zeolite, to establish all types of crystalline phases present in the mineral, and to investigate the thermal stability of these phases up to 150 °C. X-ray photoelectron spectroscopy (XPS) analysis was used for the chemical characterization of this natural clinoptilolite sample, providing important information on the cationic content and framework composition. In addition, since electrical transport takes place in the zeolite free-volume, a Brunauer–Emmett–Teller (BET) analysis of the mineral has also been performed.
Citation: Ceramics
PubDate: 2024-03-23
DOI: 10.3390/ceramics7020029
Issue No: Vol. 7, No. 2 (2024)
- Ceramics, Vol. 7, Pages 466-477: Zero-Temperature Coefficient of Resonant
Frequency in
[(Mg0.6Zn0.4)0.95Co0.05]1.02TiO3.02-Ca0.6(La0.9Y0.1)0.2667TiO3
Ultra-Low-Loss Composite Dielectrics
Authors: Yuan-Bin Chen, Jie Peng
First page: 466
Abstract: Investigating the microwave dielectric properties of ceramics prepared through the conventional solid-state route, such as x[(Mg0.6Zn0.4)0.95Co0.05]1.02TiO3.02-(1−x)Ca0.6(La0.9Y0.1)0.2667TiO3, reveals notable characteristics. [(Mg0.6Zn0.4)0.95Co0.05]1.02TiO3.02 shows a permittivity (εr) of approximately 20, a high quality factor (Q × f) ranging between 250,000 and 560,000 GHz, and a temperature coefficient of resonant frequency (τf) of approximately −65 ppm/°C. To enhance the temperature stability, Ca0.6(La0.9Y0.1)0.2667TiO3 featuring a τf value of +374 ppm/°C was incorporated into the [(Mg0.6Zn0.4)0.95Co0.05]1.02TiO3.02 composition. τf demonstrated an increase with rising Ca0.6(La0.9Y0.1)0.2667TiO3 content, reaching zero at x = 0.95. A ceramic composition of 0.95[(Mg0.6Zn0.4)0.95Co0.05]1.02TiO3.02-0.05Ca0.6(La0.9Y0.1)0.2667TiO3, incorporating 3wt.% BaCu(B2O5) as sintering aids, exhibited outstanding microwave dielectric properties: εr~22.5, Q × f~195,000 (at 9 GHz), and τf~0.1ppm/°C, with a sintering temperature at 950 °C. This material is proposed as a prospective candidate for 6G band components and GPS antennas.
Citation: Ceramics
PubDate: 2024-03-26
DOI: 10.3390/ceramics7020030
Issue No: Vol. 7, No. 2 (2024)
- Ceramics, Vol. 7, Pages 478-490: Sonochemical Synthesis of Indium Nitride
Nanoparticles and Photocatalytic Composites with Titania
Authors: Aikaterina Paraskevopoulou, Pavlos Pandis, Christos Argirusis, Georgia Sourkouni
First page: 478
Abstract: Indium nitride is an excellent semiconductor that belongs to the group of III nitride materials. Due to its unique properties, it is applied to various optoelectronic applications. However, its low thermal stability makes it difficult to synthesize. The present study introduces the synthesis of indium nitride nanoparticles, using ultrasound power (sonochemistry). The sonochemical method provides a low-cost and rapid technique for nanomaterial synthesis. InN nanoparticles were produced in only 3 h through the sonochemical reaction of InCl3 and LiN3. Xylene was used as a reaction solvent. X-ray powder diffraction (XRD) as well as high-resolution transmission electron microscopy (HRTEM) were adopted for the characterization of the obtained powder. According to our results, ultrasound contributed to the synthesis of InN nanocrystals in a cubic and a hexagonal phase. The obtained InN nanoparticles were further used to decorate titanium dioxide (TiO2) by means of ultrasound. The contribution of InN nanoparticles on the processes of photocatalysis was investigated through the degradation of methylene blue (MB), a typical organic substance acting in place of an environment pollutant. According to the obtained results, InN nanoparticles improved the photocatalytic activity of TiO2 by 41.8% compared with commercial micrometric titania.
Citation: Ceramics
PubDate: 2024-03-27
DOI: 10.3390/ceramics7020031
Issue No: Vol. 7, No. 2 (2024)
- Ceramics, Vol. 7, Pages 491-503: The Origin of the Low-Temperature Minimum
of Electrical Resistivity in Strontium Ferromolybdate Ceramics
Authors: Gunnar Suchaneck, Evgenii Artiukh, Gerald Gerlach
First page: 491
Abstract: In this work, we analyze the electrical behavior of strontium ferromolybdate below room temperature. We demonstrate that in SFMO ceramics, SFMO thin films deposited by pulsed laser deposition including (100) and (111) textured thin films, as well as in nonstoichiometric SFMO ceramics, an intergrain tunneling mechanism of charge carrier conduction leads to a decrease in resistivity with increasing temperature in the low-temperature region. This intergrain tunneling can be attributed to fluctuation-induced tunneling. On the other hand, bulk metallic resistivity of the grains, which increases with temperature, becomes dominant at higher temperatures and magnetic fluxes. The interplay of these conduction mechanisms leads to a resistivity minimum, i.e., a resistivity upturn below the temperature of minimum resistivity. Several mechanisms have been discussed in the literature to describe the low-temperature upturn in resistivity. Based on available literature data, we propose a revised model describing the appearance of a low-temperature resistivity minimum in SFMO ceramics by an interplay of fluctuation-induced tunneling and metallic conductivity. Additionally, we obtained that in the region of metallic conductivity at higher temperatures and magnetic fluxes, the pre-factor Rm of the temperature-dependent term of metallic conductivity written as a power law decreases exponentially with the temperature exponent m of this power law. Here, the value of m is determined by the charge scattering mechanism.
Citation: Ceramics
PubDate: 2024-04-01
DOI: 10.3390/ceramics7020032
Issue No: Vol. 7, No. 2 (2024)
- Ceramics, Vol. 7, Pages 504-515: Experiments Using Different Types of
Waste to Manufacture Ceramic Materials: Examples on a Laboratory Scale
Authors: Manuel M. Jordán Vidal
First page: 504
Abstract: Reusing waste as raw materials to produce other materials can entail a decrease in production costs and in the abusive use of natural resources. Furthermore, it can even improve the properties of the end product or material. In this sense, a review of the most relevant literature published in recent decades shows that numerous solutions have been proposed or implemented, such as its use to produce construction materials, catalysts, pigments, pozzolana, refractory materials, glass-ceramic products, etc. Our research group has verified the viability of using different types of waste as secondary raw materials to obtain several types of ceramic, glassy and glassceramic materials, as well as frits. This article highlights several types of industrial waste that have both non-toxic (Li, Ca and Mn) and highly toxic (Cr VI) differentiating elements that can be used in sintering and vitrification industrial processes to immobilise them or render them inert. We studied the compositions and characterised the various materials obtained, conducting toxicity and leaching tests on waste/materials designed with high amounts of chromium. A suggestion for future lines of research has been proposed.
Citation: Ceramics
PubDate: 2024-04-04
DOI: 10.3390/ceramics7020033
Issue No: Vol. 7, No. 2 (2024)
- Ceramics, Vol. 7, Pages 516-529: Effect of B2O3 and Basic Oxides on
Network Structure and Chemical Stability of Borosilicate Glass
Authors: Ming Lian, Tian Wang, Chong Wei
First page: 516
Abstract: Glass properties play crucial roles in ensuring the safety and reliability of electronic packaging. However, challenges, such as thermal expansion and resistance to acid corrosion, pose long-term service difficulties. This study investigated the impact of the microstructure on acid resistance by adjusting the glass composition. A glass material with excellent acid resistance was obtained by achieving a similar coefficient of thermal expansion to tantalum; it exhibited a weight loss rate of less than 0.03% when submerged in 38% sulfuric acid at 85 °C for 200 h. Theoretically, this glass can be used to seal wet Ta electrolytic capacitors. Differential scanning calorimetry (DSC) was used to analyze the glass transition temperature and thermal stability of borosilicate glasses. X-ray diffractometry (XRD), scanning electron microscopy (SEM), and Raman spectroscopy were used to study the microstructure of the amorphous phase of the borosilicate glass, which revealed a close relationship between the degree of network phase separation in the borosilicate glass and the degree of polymerization (isomorphic polyhedron value, IP) of the glass matrix. The IP value decreased from 3.82 to 1.98 with an increasing degree of phase separation. Boron transitions from [BO4] to [BO3] within the glass network structure with increasing boron oxide content, which diminishes the availability of free oxygen provided by alkaline oxide, resulting in a lower acid resistance. Notably, the glass exhibited optimal acid resistance at boron trioxide and mixed alkaline oxide contents of 15% and 6%, respectively. Raman experiments revealed how the distributions of various bridging oxygen atoms (Qn) affect the structural phase separation of the glass network. Additionally, Raman spectroscopy revealed the depolymerization of Q4 into Q3, thereby promoting high-temperature phase separation and highlighting the unique advantages of Raman spectroscopy for phase recognition.
Citation: Ceramics
PubDate: 2024-04-15
DOI: 10.3390/ceramics7020034
Issue No: Vol. 7, No. 2 (2024)
- Ceramics, Vol. 7, Pages 530-546: Effect of Thermal Cycling or Simulated
Gastric Acid on the Surface Characteristics of Dental Ceramic Materials
Authors: Panagiotis Pandoleon, Katia Sarafidou, Georgia K. Pouroutzidou, Anna Theocharidou, George A. Zachariadis, Eleana Kontonasaki
First page: 530
Abstract: (1) Background: The presence of various dental ceramic materials with different chemical compositions complicates clinicians’ decision making, especially in cases with a highly acidic environment appearing in patients suffering from gastroesophageal reflux disease or other eating disorders. Thermal alterations in the oral cavity can also affect surface structure and roughness, resulting in variations in both degradation mechanisms and/or bacteria adhesion. The aim of the present in vitro study was to evaluate the effect of thermal cycling and exposure to simulated gastric acid on the surface roughness of different ceramics; (2) Methods: Five groups of different ceramics were utilized, and twenty specimens were fabricated for each group. Specimens were either thermocycled for 10,000 cycles in distilled water or immersed in simulated gastric acid for 91 h. The evaluation of surface roughness was performed with optical profilometry, while scanning electron microscopy, X-ray diffraction analysis and inductively coupled plasma atomic emission spectroscopy were also performed; (4) Conclusions: Based on the combination of the surface roughness profile and structural integrity, zirconia specimens presented the smallest changes after immersion in simulated gastric acid followed by lithium disilicate materials. Zirconia-reinforced lithium silicate ceramic presented the most notable changes in microstructure and roughness after both treatments.
Citation: Ceramics
PubDate: 2024-04-15
DOI: 10.3390/ceramics7020035
Issue No: Vol. 7, No. 2 (2024)
- Ceramics, Vol. 7, Pages 547-561: Study of the Surface-Layer Softening
Effects in xLi2ZrO3–(1−x)Li4SiO4 Ceramics under Irradiation
with He2+ Ions
Authors: Dmitriy I. Shlimas, Daryn B. Borgekov, Kayrat K. Kadyrzhanov, Artem L. Kozlovskiy, Maxim V. Zdorovets
First page: 547
Abstract: The study investigates alterations in the mechanical and thermophysical properties of ceramics composed of xLi2ZrO3–(1−x)Li4SiO4 as radiation damage accumulates, mainly linked to helium agglomeration in the surface layer. This research is motivated by the potential to develop lithium-containing ceramics characterized by exceptional strength properties and a resistance to the accumulation of radiation damage and ensuing deformation distortions in the near-surface layer. The study of the radiation damage accumulation processes in the near-surface layer was conducted through intense irradiation of ceramics using He2+ ions at a temperature of 700 °C, simulating conditions closely resembling operation conditions. Following this, a correlation between the accumulation of structural modifications (value of atomic displacements) and variations in strength and thermophysical characteristics was established. During the research, it was observed that two-component ceramics exhibit significantly greater resistance to external influences and damage accumulation related to radiation exposure compared to their single-component counterparts. Furthermore, the composition that provides the highest resistance to softening in two-component ceramics is an equal ratio of the components of 0.5Li2ZrO3–0.5Li4SiO4 ceramics.
Citation: Ceramics
PubDate: 2024-04-16
DOI: 10.3390/ceramics7020036
Issue No: Vol. 7, No. 2 (2024)
- Ceramics, Vol. 7, Pages 562-578: Ultra-Broadband Plasmon Resonance in Gold
Nanoparticles Precipitated in ZnO-Al2O3-SiO2 Glass
Authors: Georgiy Shakhgildyan, Leon Avakyan, Grigory Atroshchenko, Maxim Vetchinnikov, Alexandra Zolikova, Elena Ignat’eva, Mariam Ziyatdinova, Elena Subcheva, Lusegen Bugaev, Vladimir Sigaev
First page: 562
Abstract: Optical materials with a tunable localized surface plasmon resonance (LSPR) are of great interest for applications in photonics and optoelectronics. In the present study, we explored the potential of generating an LSPR band with an ultra-broad range of over 1000 nm in gold nanoparticles (NPs), precipitated through a thermal treatment in ZnO-Al2O3-SiO2 glass. Using optical absorption spectroscopy, we demonstrated that the LSPR band’s position and shape can be finely controlled by varying the thermal treatment route. Comprehensive methods including Raman spectroscopy, X-ray diffraction, and high-resolution transmission electron microscopy were used to study the glass structure, while computational approaches were used for the theoretical description of the absorption spectra. The obtained results allowed us to suggest a scenario responsible for an abnormal LSPR band broadening that includes a possible interparticle plasmonic coupling effect taking place during the liquid–liquid phase separation of the heat-treated glass. The formation of gold NPs with an ultra-broad LSPR band in glasses holds promise for sensitizing rare earth ion luminescence for new photonics devices.
Citation: Ceramics
PubDate: 2024-04-25
DOI: 10.3390/ceramics7020037
Issue No: Vol. 7, No. 2 (2024)
- Ceramics, Vol. 7, Pages 579-595: Hot Corrosion Behavior of Plasma-Sprayed
Gd2Zr2O7/YSZ Functionally Graded Thermal Barrier Coatings
Authors: Rajasekaramoorthy Manogaran, Karthikeyan Alagu, Anderson Arul, Anandh Jesuraj, Dinesh Kumar Devarajan, Govindhasamy Murugadoss, Kamalan Kirubaharan Amirtharaj Mosas
First page: 579
Abstract: The development of advanced thermal barrier coating (TBC) materials with better hot corrosion resistance, phase stability, and residual stresses is an emerging research area in the aerospace industry. In the present study, four kinds of TBCs, namely, single-layer yttria-stabilized zirconia (YSZ), single-layer gadolinium zirconate (GZ), bilayer gadolinium zirconate/yttria-stabilized zirconia (YSZ/GZ), and a multilayer functionally graded coating (FGC) of YSZ and GZ, were deposited on NiCrAlY bond-coated nickel-based superalloy (Inconel 718) substrates using the atmospheric plasma spray technique. The hot corrosion behavior of the coatings was tested by applying a mixture of Na2SO4 and V2O5 onto the surface of TBC, followed by isothermal heat treatment at 1273 K for 50 h. The characterization of the corroded samples was performed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) to identify physical and chemical changes in the coatings. GIXRD was used to analyze the residual stresses of the coatings. Residual stress in the FGC coating was found to be −15.2 ± 10.6 MPa. The wear resistance of TBCs is studied using a linear reciprocating tribometer, and the results indicate that gadolinium zirconate-based TBCs showed better performance when deposited in bilayer and multilayered functionally graded TBC systems. The wear rate of as-coated FGC coatings was determined to be 2.90 × 10−4 mm3/Nm, which is lower than the conventional YSZ coating.
Citation: Ceramics
PubDate: 2024-04-29
DOI: 10.3390/ceramics7020038
Issue No: Vol. 7, No. 2 (2024)
- Ceramics, Vol. 7, Pages 596-606: Experimental Design of the Adhesion
between a PEI/Glass Fiber Composite and the AA1100 Aluminum Alloy with
Oxide Coating Produced via Plasma Electrolytic Oxidation (PEO)
Authors: Rafael Resende Lucas, Luis Felipe Barbosa Marques, Luis Rogerio de Oliveira Hein, Edson Cocchieri Botelho, Rogério Pinto Mota
First page: 596
Abstract: In this study, the AA1100 aluminum alloy underwent the plasma electrolytic oxidation (PEO) process to enhance its adhesion to a thermoplastic composite of polyetherimide (PEI) reinforced with glass fiber, following ASTM D1002:10 standards. A 23 factorial design was employed, varying three parameters in the oxidation process: immersion time, applied electric potential, and electrolyte concentration (Na2B4O7). The joining of aluminum and thermoplastic composite samples was achieved through oxy-fuel welding (OFW), using oxygen and acetylene gases. For the characterization of the joined samples, a universal tensile testing machine was utilized with a displacement speed of 1.5 mm/min. The analysis of the oxide coating involved scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and Fourier transform infrared spectroscopy (FT-IR). Through variance analysis, it was determined that the statistical model encompasses approximately 80% of the variability in the adhesion process between materials. An improvement of up to 104% in adhesion between the materials was observed with the process, indicating an effective bond due to the presence of the thermoplastic matrix in the treated aluminum sample. This improvement is attributed to the morphology of the oxide coating, resembling corals, with micro-pores and recesses that facilitated mechanical anchoring.
Citation: Ceramics
PubDate: 2024-04-29
DOI: 10.3390/ceramics7020039
Issue No: Vol. 7, No. 2 (2024)
- Ceramics, Vol. 7, Pages 607-624: Enhancing Transparency in Non-Cubic
Calcium Phosphate Ceramics: Effect of Starting Powder, LiF Doping, and
Spark Plasma Sintering Parameters
Authors: Kacper Albin Prokop, Sandrine Cottrino, Vincent Garnier, Gilbert Fantozzi, Yannick Guyot, Georges Boulon, Małgorzata Guzik
First page: 607
Abstract: Our objective is to achieve a new good-quality and mechanically durable high-transparency material that, when activated by rare earth ions, can be used as laser sources, scintillators, or phosphors. The best functional transparent ceramics are formed from high-symmetry systems, mainly cubic. Considering hexagonal hydroxyapatite, which shows anisotropy, the particle size of the initial powder is extremely important and should be of the order of several tens of nanometers. In this work, transparent micro-crystalline ceramics of non-cubic Ca10(PO4)6(OH)2 calcium phosphate were fabricated via Spark Plasma Sintering (SPS) from two types of nanopowders i.e., commercially available (COM. HA) and laboratory-made (LAB. HA) via the hydrothermal (HT) protocol. Our study centered on examining how the quality of sintered bodies is affected by the following parameters: the addition of LiF sintering agent, the temperature during the SPS process, and the quality of the starting nanopowders. The phase purity, microstructure, and optical transmittance of the ceramics were investigated to determine suitable sintering conditions. The best optical ceramics were obtained from LAB. HA nanopowder with the addition of 0.25 wt.% of LiF sintered at 1000 °C and 1050 °C.
Citation: Ceramics
PubDate: 2024-04-30
DOI: 10.3390/ceramics7020040
Issue No: Vol. 7, No. 2 (2024)
- Ceramics, Vol. 7, Pages 625-638: Effect of Processing Routes on Physical
and Mechanical Properties of Advanced Cermet System
Authors: Vikas Verma, Margarita García-Hernández, Jorge Humberto Luna-Domínguez, Edgardo Jonathan Suárez-Domínguez, Samuel Monteiro Júnior, Ronaldo Câmara Cozza
First page: 625
Abstract: The present research focuses on the effects of different processing routes on the physical and mechanical properties of nano Ti(CN)-based cermets with metallic binders. Tungsten carbide (WC) is added as a secondary carbide and Ni-Co is added as a metallic binder to nano Ti(CN)-based cermet processed via conventional and spark plasma sintering (SPS). A systematic comparison of the composition and sintering conditions for different cermets’ systems was carried out to design novel composition and sintering conditions. Nano TiCN powder was prepared by 30 h of ball milling. The highest density of >98.5% was achieved for the SPS-processed cermets sintered at 1200 °C and 1250 °C for 3 min at 60 MPa of pressure in comparison to the conventionally sintered cermets at 1400 °C for 1 h with a two-stage compaction process—uniaxially at 150 MPa and isostatically at 300 MPa of pressure. Comparative X-ray diffraction (XRD) analysis of the milled powders at different time intervals was performed to understand the characteristics of the as-received and milled powders. Peak broadening was observed after 5 h of ball milling, and it increased to 30 hr. Also, peak broadening and a refined carbide size was observed in the XRD and scanning electron microscope (SEM) micrographs of the SPS-processed cermet. Transmission electron microscope (TEM) analysis of the milled powder showed that its internal structure had a regular periodic arrangement of planes. SEM base scattered electron (BSE) images of all the cermets primarily showed three major microstructural phases of the core–rim–binder with black, grey, and white contrast, respectively. With the present sintering conditions, a high hardness of ~16 GPa and a fracture toughness of ~9 MPa m1/2 were obtained for SPS-processed cermets sintered at higher temperatures.
Citation: Ceramics
PubDate: 2024-05-02
DOI: 10.3390/ceramics7020041
Issue No: Vol. 7, No. 2 (2024)
- Ceramics, Vol. 7, Pages 639-651: Utilization of Waste Marble and Bi2O3-NPs
as a Sustainable Replacement for Lead Materials for Radiation Shielding
Applications
Authors: Khalid Alsafi, Mohamed A. El-Nahal, Wafa M. Al-Saleh, Haifa M. Almutairi, Esraa H. Abdel-Gawad, Mohamed Elsafi
First page: 639
Abstract: In an attempt to reutilize marble waste, a new approach is presented in the current study to promote its use in the field of shielding against ionizing radiation. In this study, we aimed to develop a novel and sustainable/eco-friendly lead-free radiation shielding material by improving artificial marble (AM) produced from marble waste combined with polyester by reinforcing it with bismuth oxide (Bi2O3) nanoparticles. Six samples of AM samples doped with different concentrations (0%, 5%, 10%, 15%, 20%, and 25%) of Bi2O3 nanoparticles were prepared. The linear attenuation coefficient (LAC) values were measured experimentally through the narrow beam method at different energies (0.0595 MeV, 0.6617 MeV, 1.1730 MeV, and 1.330 MeV) for all samples with various concentrations of Bi2O3. Radiological shielding parameters such as half value layer (HVL), tenth-value layer (TVL), and radiation shielding efficiency (RSE) were estimated and compared for all the different samples. The results prove that increasing the concentration of Bi2O3 leads to the enhancement of the radiation shielding properties of the AM as a shielding material. It was observed that as the energy increases, the efficiency of the samples falls. High energy dependence was found when calculating the HVL and TVL values of the samples, which increased with increases in the energy of the incident photons. A comparison between the sample with the most efficient gamma radiation attenuation capability (AM-25%), concrete, and lead was conducted, and a discussion regarding their radiation shielding properties is presented herein. The results show that the AM-25% sample is superior to the ordinary concrete over all the studied energy ranges, as evidenced by its significantly lower HVLs. On the contrary, lead is superior to the AM-25% sample over all the studied energy ranges owing to its unbeatable density as a shielding material. Overall, this new type of artificial marble has the potential to be used as a radiation shielding material at low- to medium-gamma energy regions, specifically in medical imaging and radiation therapy.
Citation: Ceramics
PubDate: 2024-05-07
DOI: 10.3390/ceramics7020042
Issue No: Vol. 7, No. 2 (2024)
- Ceramics, Vol. 7, Pages 652-679: Ceramic Matrix Composites:
Classifications, Manufacturing, Properties, and Applications
Authors: Shriya Shrivastava, Dipen Kumar Rajak, Tilak Joshi, Dwesh K. Singh, D. P. Mondal
First page: 652
Abstract: Ceramic matrix composites (CMCs) are a significant advancement in materials science and engineering because they combine the remarkable characteristics of ceramics with the strength and toughness of fibers. With their unique properties, which offer better performance and endurance in severe settings, these advanced composites have attracted significant attention in various industries. At the same time, lightweight ceramic matrix composites (LCMCs) provide an appealing alternative for a wide range of industries that require materials with excellent qualities such as high-temperature stability, low density, corrosion resistance, and excellent mechanical performance. CMC uses will expand as production techniques and material research improve, revolutionizing aerospace, automotive, and other industries. The effectiveness of CMCs primarily relies on the composition of their constituent elements and the methods employed in their manufacturing. Therefore, it is crucial to explore the functional properties of various global ceramic matrix reinforcements, their classifications, and the manufacturing techniques used in CMC fabrication. This study aims to overview a diverse range of CMCs reinforced with primary fibers, including their classifications, manufacturing techniques, functional properties, significant applications, and global market size.
Citation: Ceramics
PubDate: 2024-05-10
DOI: 10.3390/ceramics7020043
Issue No: Vol. 7, No. 2 (2024)
- Ceramics, Vol. 7, Pages 680-688: Nanosized Tungsten Powder Synthesized
Using the Nitridation–Decomposition Method
Authors: Qing-Yin He, Ben-Li Zhao, Shi-Kuan Sun
First page: 680
Abstract: A facile, one-step nitridation–decomposition method was developed for the synthesis of nanosized tungsten powder with a high surface area. This approach involved the nitridation of WO3 in NH3 to form mesoporous tungsten nitride (W2N), followed by in situ decomposition of W2N to directly yield single-phase W particles. The phase and morphology evolution during the synthesis were systematically investigated and compared with the carbothermal reduction of WO3. It was revealed that powdered tungsten product with single-phase particles was obtained after nitridation at 800 °C combined with in situ decomposition at 1000 °C, displaying an average particle size of 15 nm and a large specific surface area of 6.52 m2/g. Furthermore, the proposed method avoided the limitations associated with intermediate phase formation and coarsening observed in carbothermal reduction, which resulted in the growth of W particles up to ~4.4 μm in size. This work demonstrates the potential of the nitridation–decomposition approach for the scalable and efficient synthesis of high-quality, fine-grained tungsten powder.
Citation: Ceramics
PubDate: 2024-05-11
DOI: 10.3390/ceramics7020044
Issue No: Vol. 7, No. 2 (2024)
- Ceramics, Vol. 7, Pages 689-697: Effect of Acid Surface Treatments on the
Shear Bond Strength of Metal Bracket to Zirconia Ceramics
Authors: Punchanit Wongrachit, Bancha Samruajbenjakun, Boonlert Kukiattrakoon, Tanapat Jearanai, Supontep Teerakanok, Pannapat Chanmanee
First page: 689
Abstract: The surface treatment of zirconia prior to bonding remains controversial and unclear. This study aimed to compare the shear bond strength (SBS) of metal brackets to zirconia under surface treatments with either 4% HF or 37% PA in both immediate loading (IML) and artificial aging by thermocycling (TMC). Methods: Eighty-four zirconia were randomly assigned to six groups based on the surface treatment and artificial aging by TMC: (1) No surface treatment (NT); (2) NT + TMC; (3) HF (4% HF for 2 min); (4) HF + TMC; (5) PA (37% PA for 2 min); and (6) PA + TMC. After bracket bonding, only the TMC groups were thermocycled for 5000 cycles. The SBS and adhesive remnant index (ARI) of all groups were analyzed (p < 0.01). Results: TMC significantly lowered the SBS more than the IML in all acid surface treatment groups (p < 0.01). The ARI score after TMC was significantly higher than the IML in all acid surface treatment groups (p < 0.001). No significant differences in the SBS values or ARI scores were observed among the surface treatments (p > 0.01). Conclusions: Two-minute simple etching methods, using either 4% HF or 37% PA, showed an insufficient SBS of metal orthodontic brackets to zirconia after TMC.
Citation: Ceramics
PubDate: 2024-05-14
DOI: 10.3390/ceramics7020045
Issue No: Vol. 7, No. 2 (2024)
- Ceramics, Vol. 7, Pages 698-711: Origin of Temperature Coefficient of
Resonance Frequency in Rutile Ti1−xZrxO2 Microwave Ceramics
Authors: Izaz Khan, Aneela Khan, Raz Muhammad, Minmin Mao, Dandan Han, Kaixin Song, Wen Lei, Dawei Wang
First page: 698
Abstract: In this study, we report the effect of Zr4+ doping on the optical energy gap and microwave dielectric properties of rutile TiO2. Rietveld analysis explicitly confirmed that Zr4+ occupies the octahedral site, forming a single-phase tetragonal structure below the solubility limit (x < 0.10). Notably, at x = 0.025, a significant enhancement in Q × fo was observed. This enhancement was attributed to the reduction in dielectric loss, associated with a decrease in oxygen vacancies and a lower concentration of Ti3+ paramagnetic centers. This conclusion was supported by Raman and electron paramagnetic resonance spectroscopy, respectively. The origin of high τf in rutile Ti1−xZrxO2 is explained on the basis of the octahedral distortion/tetragonality ratio, covalency, and bond strength.
Citation: Ceramics
PubDate: 2024-05-23
DOI: 10.3390/ceramics7020046
Issue No: Vol. 7, No. 2 (2024)
- Ceramics, Vol. 7, Pages 712-734: Lead-Free NaNbO3-Based Ceramics for
Electrostatic Energy Storage Capacitors
Authors: Sairatun Nesa Soheli, Zhilun Lu, Dongyang Sun, Islam Shyha
First page: 712
Abstract: The burgeoning significance of antiferroelectric (AFE) materials, particularly as viable candidates for electrostatic energy storage capacitors in power electronics, has sparked substantial interest. Among these, lead-free sodium niobate (NaNbO3) AFE materials are emerging as eco-friendly and promising alternatives to lead-based materials, which pose risks to human health and the environment, attributed to their superior recoverable energy density and dielectric breakdown strength. This review offers an insightful overview of the fundamental principles underlying antiferroelectricity and the applications of AFE materials. It underscores the recent advancements in lead-free NaNbO3-based materials, focusing on their crystal structures, phase transitions, and innovative strategies devised to tailor their electrostatic energy storage performance. Finally, this review delineates the prevailing challenges and envisages future directions in the realm of NaNbO3-based electrostatic energy storage capacitors, with the goal of fostering further advancements in this pivotal field.
Citation: Ceramics
PubDate: 2024-05-23
DOI: 10.3390/ceramics7020047
Issue No: Vol. 7, No. 2 (2024)
- Ceramics, Vol. 7, Pages 735-742: Microwave-Assisted Hydrothermal Synthesis
of Hydroxyapatite Flakes as Substrates for Titanium Dioxide Film
Deposition
Authors: Néstor Méndez-Lozano, Eduardo E. Pérez-Ramírez, Miguel de la Luz-Asunción
First page: 735
Abstract: This article describes the synthesis of hydroxyapatite (HAp) flakes through a microwave-assisted hydrothermal method. These flakes suggest possible applications as a substrate for depositing titanium dioxide (TiO2) films using chemical vapor deposition with metal–organic precursors (MOCVD). The results reveal the formation of crystalline hydroxyapatite characterized by a uniform morphology. Additionally, we demonstrated the successful deposition of TiO2 coatings on the hydroxyapatite flakes, resulting in a distinctive faceted prism morphology. Our findings affirm the effective synthesis of the HAp/TiO2 composite material. To further explore the material’s practical applications, we recommend assessing the photocatalytic activity of these composite membranes in future research.
Citation: Ceramics
PubDate: 2024-05-28
DOI: 10.3390/ceramics7020048
Issue No: Vol. 7, No. 2 (2024)
- Ceramics, Vol. 7, Pages 743-758: Improving the Transparency of a MgAl2O4
Spinel Damaged by Sandblasting through a SiO2-ZrO2 Coating
Authors: Akram Zegadi, Abdelwahhab Ayadi, Ikram Khellaf, Mohamed Hamidouche, Gilbert Fantozzi, Alicia Durán, Yolanda Castro
First page: 743
Abstract: Transparent materials in contact with harmful environments such as sandstorms are exposed to surface damage. Transparent MgAl2O4 spinel used as protective window, lens or laser exit port, among others, is one of the materials affected by natural aggressions. The impact of sand particles can cause significant defects on the exposed surface, thus affecting its optical and mechanical behavior. The aim of this work is to improve the surface state of a spinel damaged surface by the deposition of a thin layer of SiO2-ZrO2. For this purpose, spinel samples obtained from different commercial powders sintered by Spark Plasma Sintering were sandblasted and further coated with a SiO2-ZrO2 thin layer. The coating was successfully synthesized by the sol/gel method, deposited on the sandblasted samples and then treated at 900 °C, reaching a final thickness of 250 nm. The results indicated that sandblasting significantly affects the surface of the spinel samples as well as the optical transmission, confirmed by UV-visible spectroscopy and profilometry tests. However, the deposition of a SiO2-ZrO2 coating modifies the UV-visible response. Thus, the optical transmission of the S25CRX12 sample presents the best transmission values of 81%, followed by the S25CRX14 sample then the S30CR sample at 550 nm wavelength. An important difference was observed between sandblasted samples and coated samples at low and high wavelengths. At low wavelengths (around 200 nm), sandblasting tends to improve significantly the transmission of spinel samples, which exhibit a low transmission in the pristine state. This phenomenon can be attributed to the healing of small superficial defects responsible for the degradation of transmission such as pores or flaws. When the initial transmission at 200 nm is high, the sandblasting worsens the transmission. Sandblasting reduces slightly the transmission values for long wavelengths due to the formation of large superficial defects like chipping by creation and propagation of lateral cracks. The coating of the sandblasted samples exhibits some healing of defects induced by sandblasting. The deposition of the SiO2-ZrO2 layer induces a clear increase in the optical transmission values, sometimes exceeding the initial values of the transmission in the pristine state.
Citation: Ceramics
PubDate: 2024-05-28
DOI: 10.3390/ceramics7020049
Issue No: Vol. 7, No. 2 (2024)
- Ceramics, Vol. 7, Pages 759-776: Investigation of Variability of Flaw
Strength Distributions on Brittle SiC Ceramic
Authors: Jacques Lamon
First page: 759
Abstract: The present paper investigates flaw strength distributions established using various flexural tests on batches of SiC bar test specimens, namely four-point bending as well as three-point bending tests with different span lengths. Flaw strength is provided by the elemental stress operating on the critical flaw at the fracture of a test specimen. Fracture-inducing flaws and their locations are identified using fractography. A single population of pores was found to dominate the fracture. The construction of diagrams of p-quantile vs. elemental strengths was aimed at assessing the Gaussian nature of flaw strengths. Then, empirical cumulative distributions of strengths were constructed using the normal distribution function. The Weibull distributions of strengths are then compared to the normal reference distributions. The parameters of the Weibull cumulative probability distributions are estimated using maximum likelihood and moment methods. The cumulative distributions of flexural strengths for the different bending tests are predicted from the flaw strength density function using the elemental strength model, and from the cumulative distribution of flexural strength using the Weibull function. Flaw strength distributions that include the weaker flaws that are potentially present in larger test pieces are extrapolated using the p-quantile diagrams. Implications are discussed regarding the pertinence of an intrinsically representative flaw strength distribution, considering failure predictions. Finally, the influence of the characteristics of fracture-inducing flaw populations expressed in terms of flaw strength interval, size, dispersion, heterogeneity, and reproducibility with volume change is examined.
Citation: Ceramics
PubDate: 2024-06-04
DOI: 10.3390/ceramics7020050
Issue No: Vol. 7, No. 2 (2024)
- Ceramics, Vol. 7, Pages 777-795: CaCO3-Infused Carbon Fiber Aerogels:
Synthesis and Characterization
Authors: Cristina Mosoarca, Iosif Hulka, Pavel Șchiopu, Florina S. Rus, Radu Bănică
First page: 777
Abstract: Carbon aerogels represent a distinctive category of high surface area materials derived from sol-gel chemistry. Functionalizing these aerogels has led to the development of composite aerogels with the potential for a wider range of applications. In this study, the technique of lyophilization was employed to fabricate aerogel composites consisting of inorganic salts and cellulosic fibers. Cellulose carbonization can occur through chemical dehydration by heat treatment in an inert atmosphere. X-ray diffraction analysis spectra and scanning electron microscopy images indicate that the formed polymeric composites contain partially carbonized cellulose fibers, amorphous carbon, and calcium carbonates. CaCO3 primarily forms through the reaction of CaCl2, which moistens cellulose or amorphous carbon fibers with CO2 in ammonia fumes. The water loss in 3D structures was analyzed using thermogravimetric analysis, Fourier Transform Infrared Spectroscopy, and ultraviolet-visible-near-infrared spectroscopy. Depending on the synthesis method, 3D structures can be created from partially or completely dehydrated cellulose fibers. The aerogels were examined for their ability to support the growth of bacterial biofilm and then adorned with metal silver and AgCl to produce bactericidal products. Due to their open pores and CaCO3 content, these aerogels can serve as durable and environmentally friendly thermal insulators with bactericidal properties, as well as a medium for absorbing acidic gases.
Citation: Ceramics
PubDate: 2024-06-06
DOI: 10.3390/ceramics7020051
Issue No: Vol. 7, No. 2 (2024)
- Ceramics, Vol. 7, Pages 796-806: Fabrication of Dicarboxylic-Acid- and
Silica-Substituted Octacalcium Phosphate Blocks with Stronger Mechanical
Strength
Authors: Sugiura, Saito, Yamada, Horie
First page: 796
Abstract: Octacalcium phosphate (OCP) is an attractive base material to combine into components developed for medical purposes, especially those used in bone replacement procedures, not only because of its excellent biocompatibility but also because of its ability to intercalate with multiple types of molecular layers such as silica, dicarboxylic acid, and various cations. On the other hand, there are no examples of simultaneous substituting for several different compounds on OCPs. Therefore, in this study, the physical and mechanical strength (DTS: diametral tensile strength) of OCPs substituted with both silica and dicarboxylic acids (thiomalate: SH-malate) were evaluated. By optimizing the amount of SH-malate, we were able to prepare a block consisting of OCPs with both silica and SH-malate supported in the interlayer. The composition of the OCP-based compound comprising this block was Ca8Na1.07H6.33(PO4)4.44(SiO4)1.32(SH-malate)2.40∙nH2O. Interestingly, the low mechanical strength, a drawback of silica-substituted OCP blocks, could be improved by dicarboxylic acid substituting. The dicarboxylic acid addition increased the mechanical strength of silica-substituted OCP blocks, and the acid successfully incorporated into the interlayer, even with the presence of silica. These results are expected to advance the creation of better silica-substituted OCPs and improved bone replacement materials.
Citation: Ceramics
PubDate: 2024-06-07
DOI: 10.3390/ceramics7020052
Issue No: Vol. 7, No. 2 (2024)
- Ceramics, Vol. 7, Pages 807-820: Mullite 3D Printed Humidity Sensors
Authors: Yurii Milovanov, Arianna Bertero, Bartolomeo Coppola, Paola Palmero, Jean-Marc Tulliani
First page: 807
Abstract: Mullite substrates with two different porosities were 3D printed, and tested as humidity sensors. To evaluate the effects of porosity on humidity sensitivity, the samples were sintered at 1400 °C (Sensor 1) and 1450 °C (Sensor 2). The sensors were tested in a range from 0% to 85% relative humidity (RH) at room temperature. When exposed to water vapor at room temperature, the impedance value dropped down from 155 MΩ under dry air to 480 kΩ under 85 RH% for Sensor 1 and from 115 MΩ under dry air to 410 kΩ for Sensor 2. In addition, response time and recovery time were below 2 min, whatever the firing temperature, when RH changed from 0% to 74%. Finally, tests carried out involving ammonia, methane, carbon dioxide and nitrogenous oxide, as well as ethanol and acetone, showed no interference.
Citation: Ceramics
PubDate: 2024-06-10
DOI: 10.3390/ceramics7020053
Issue No: Vol. 7, No. 2 (2024)
- Ceramics, Vol. 7, Pages 821-839: Influence of Nanoceramic-Plated Waste
Carbon Fibers on Alkali-Activated Mortar Performance
Authors: Matteo Sambucci, Yazeed A. Al-Noaimat, Seyed Mostafa Nouri, Mehdi Chougan, Seyed Hamidreza Ghaffar, Marco Valente
First page: 821
Abstract: Waste carbon fibers as reinforcing elements in construction materials have recently gained increasing interest from researchers, providing outstanding strength performance and a lower environmental footprint compared to virgin fibers. Combination with cement-free binders, namely alkali-activated materials, is becoming increasingly important for sustainable development in the construction industry. This paper presents results relating to the potential use of waste carbon fibers in alkali-activated mortars. The waste carbon fiber fraction utilized in this research is difficult to integrate as reinforcement in ceramic–cementitious matrices due to its agglomerated form and chemical inertness. For this reason, a nanoceramic coating pretreatment based on nanoclay has been implemented to attempt improvements in terms of deagglomeration, dispersibility, and compatibility with alkali-activated materials. After chemical–physical and microstructural analysis on the nanoclay-plated fibers (including X-ray diffraction, IR spectroscopy, contact angle measurements, and electron microscopy) mortars were produced with four different dosages of treated and untreated waste fibers (0.25 wt.%, 0.5 wt.%, 0.75 wt.%, and 1 wt.%). Mechanical tests and fractographic investigations were then performed. The nanoclay coating interacts compatibly with the waste carbon fibers and increases their degree of hydrophilicity to improve their deagglomeration and dispersion. Compared to the samples incorporating as-received fillers, the addition of nanoclay-coated fibers improved the strength behavior of the mortars, recording a maximum increase in flexural strength of 19% for a fiber content of 0.25 wt.%. This formulation is the only one providing an improvement in mechanical behavior compared to unreinforced mortar. Indeed, as the fibrous reinforcement content increases, the effect of the nanoclay is attenuated by mitigating the improvement in mechanical performance.
Citation: Ceramics
PubDate: 2024-06-19
DOI: 10.3390/ceramics7020054
Issue No: Vol. 7, No. 2 (2024)
- Ceramics, Vol. 7, Pages 29-38: Effect of Thickness on Ferroelectric
Properties of Bi3.25La0.75Ti3O12 Thin Films
Authors: Wenfeng Yue, Yali Cai, Quansheng Guo, Dawei Wang, Tingting Jia
First page: 29
Abstract: The pursuit of low-power/low-voltage operation in devices has prompted a keen interest in the mesoscale effects within ferroelectric thin films. The downsizing of ferroelectrics can significantly influence performance; for instance, the remanent polarization and coercive field are susceptible to alterations based on thickness. In this study, randomly oriented Bi3.25La0.75Ti3O12 thin films were fabricated on Pt/Ti/SiO2/Si substrates using the sol–gel method, and SEM observations revealed rod-like grains in all thin films. The investigation delved into the correlation between dielectric and ferroelectric properties with thin film thickness. The thin film exhibited an increased remanent polarization and a reduced coercive electric field. Additionally, the ferroelectric domain structure was scrutinized through PFM, and the resistor properties of the BLT4 thin film were studied, which shows the potential of BLT thin films in non-volatile memory and memristor.
Citation: Ceramics
PubDate: 2024-01-06
DOI: 10.3390/ceramics7010003
Issue No: Vol. 7, No. 1 (2024)
- Ceramics, Vol. 7, Pages 39-54: Study of the Resistance of
Lithium-Containing Ceramics to Helium Swelling
Authors: Artem L. Kozlovskiy, Dmitriy I. Shlimas, Daryn B. Borgekov, Maxim V. Zdorovets
First page: 39
Abstract: The paper presents the results of studies of the resistance of lithium ceramics to helium swelling during its accumulation in the structure of the near-surface layer, and the identification of the three types of lithium ceramics most resistant to radiation degradation: Li4SiO4, Li2TiO3, and Li2ZrO3. The simulation of helium swelling under high-dose irradiation was carried out by irradiation with He2+ ions with fluences of 1 × 1016 ion/cm2–5 × 1017 ion/cm2, which allows for simulating the implanted helium accumulation with a high concentration in the damaged surface layer (about 500 nm thick). The samples were irradiated at a temperature of 1000 K, the choice of which was determined by the possibility of simulating radiation damage as close as possible to real operating conditions. Such accumulation can result in the formation of gas-filled bubbles. Through the application of X-ray phase analysis, indentation testing, and thermophysical parameter assessments, it was ascertained that among the three ceramic types, Li4SiO4 ceramics exhibit the highest resistance to helium-induced swelling. These ceramics experienced less significant alterations in their properties compared to the other two types. An analysis of the correlation between the structural and strength parameters of lithium-containing ceramics revealed that the most significant changes occur when the volumetric swelling of the crystal lattice becomes the dominant factor in structural alterations. This phenomenon is manifested as an accelerated degradation of strength characteristics, exceeding 10%. At the same time, analysis of these alterations in the stability of thermophysical parameters to the accumulation of structural distortions revealed that, regardless of the type of ceramics, the degradation of thermophysical properties is most pronounced under high-dose irradiation (above 1017 ion/cm2).
Citation: Ceramics
PubDate: 2024-01-08
DOI: 10.3390/ceramics7010004
Issue No: Vol. 7, No. 1 (2024)
- Ceramics, Vol. 7, Pages 55-67: Improving the Quality of Ceramic Products
by Removing the Defective Surface Layer
Authors: Alexander S. Metel, Marina A. Volosova, Enver S. Mustafaev, Yury A. Melnik, Anna A. Okunkova, Sergey N. Grigoriev
First page: 55
Abstract: The surface of ceramic products manufactured using diamond grinding is replete with shallow scratches, deep grooves and other defects. The thickness of the defective layer amounts to 3–4 µm and it must be removed to increase wear resistance of the products when exposed to intense thermomechanical loads. In this study, removal of the defective layers from samples made of ZrO2, Al2O3 and Si3N4 with a beam of fast argon atoms was carried out with a stripping rate of up to 5 µm/h. To prevent contamination of the source of fast argon atoms by the sputtered dielectric material, the beam was compressed and passed to the sample through a small hole in a wide screen. Due to the removal of the defective layer, abrasive wear decreased by an order of magnitude and the adhesion of coatings deposited on the cleaned ceramic surfaces improved significantly.
Citation: Ceramics
PubDate: 2024-01-11
DOI: 10.3390/ceramics7010005
Issue No: Vol. 7, No. 1 (2024)
- Ceramics, Vol. 7, Pages 68-85: Ceramics 3D Printing: A Comprehensive
Overview and Applications, with Brief Insights into Industry and Market
Authors: Mohamed Abdelkader, Stanislav Petrik, Daisy Nestler, Mateusz Fijalkowski
First page: 68
Abstract: 3D printing enables the creation of complex and sophisticated designs, offering enhanced efficiency, customizability, and cost-effectiveness compared to traditional manufacturing methods. Ceramics, known for their heat resistance, hardness, wear resistance, and electrical insulation properties, are particularly suited for aerospace, automotive, electronics, healthcare, and energy applications. The rise of 3D printing in ceramics has opened new possibilities, allowing the fabrication of complex structures and the use of diverse raw materials, overcoming the limitations of conventional fabrication methods. This review explores the transformative impact of 3D printing, or additive manufacturing, across various sectors, explicitly focusing on ceramics and the different 3D ceramics printing technologies. Furthermore, it presents several active companies in ceramics 3D printing, proving the close relation between academic research and industrial innovation. Moreover, the 3D printed ceramics market forecast shows an annual growth rate (CAGR) of more than 4% in the ceramics 3D printing market, reaching USD 3.6 billion by 2030.
Citation: Ceramics
PubDate: 2024-01-18
DOI: 10.3390/ceramics7010006
Issue No: Vol. 7, No. 1 (2024)
- Ceramics, Vol. 7, Pages 86-100: Revascularization of Non-Vital, Immature,
Permanent Teeth with Two Bioceramic Cements: A Randomized Controlled Trial
Authors: Alaa Shaker, Mohamed Salem Rekab, Mohammad Alharissy, Naji Kharouf
First page: 86
Abstract: The aim of this study was to clinically and radiographically assess the effects of two bioceramic cements as coronal plug materials for the revascularization of non-vital, immature, permanent teeth with apical periodontitis. Twenty non-vital, immature, permanent, anterior teeth with apical periodontitis were included in this study. Samples were randomly divided into two groups based on the coronal plug materials used; group I (GI): Well Root PT (Vericom, Gangwon-do, Korea) and group II (GII): MTA Biorep (Itena Clinical, Paris, France) (n = 10). Follow-up was conducted clinically and radiographically for up to 12 months to evaluate the changes in root dimensions and resolution of the periapical disease and investigate the degree of success. Data were statistically analyzed using ANOVA tests and Mann–Whitney U tests at a 0.05 significance level. At 12 months, none of the patients in either test group had clinical signs/symptoms. There was a slight increase in root length (4.4% in GI and 3.4% in GII) and a slight increase in dentin wall thickness (10.2% in GI and 9.9% in GII) with no statistically significant (p > 0.05) differences. Whilst there was a significant decrease in lesion dimension in all patients after 12 moths of treatment (93% in GI and 91% in GII), there were no statistically significant differences between the two study groups (p > 0.05). Regarding the degree of success, all cases (100%) achieved the primary goal (the elimination of symptoms and the evidence of bony healing), while 60% in GI and 40% in GII achieved the secondary goal (increased root wall thickness and/or increased root length). No statistically significant difference was found between groups (p > 0.05). Both bioceramic cements showed satisfactory clinical and radiographic findings. Premixed calcium aluminosilicate and tricalcium silicate cements could be used as coronal plug materials in revascularization procedures. Bioceramic cements can be considered promising coronal plug materials for the revascularization of immature, permanent teeth with necrotic pulps and apical periodontitis due to their physicochemical and biological properties.
Citation: Ceramics
PubDate: 2024-01-25
DOI: 10.3390/ceramics7010007
Issue No: Vol. 7, No. 1 (2024)
- Ceramics, Vol. 7, Pages 101-114: Glass Composition for Coating and Bonding
of Polycrystalline Spinel Ceramic Substrates
Authors: Jacob Hormadaly
First page: 101
Abstract: Design considerations of the lead-based glass composition was broadened beyond the two known criteria of matched index of refraction and thermal coefficient of expansion to include previous studies of thick film materials. Five criteria for the glass-design composition were used: matched index of refraction and thermal coefficient of expansion, components (MgO and Al2O3) to slow down dissolution of spinel (MgAl2O4) into the glass, non-crystallizing glass in a broad temperature range and glass with good chemical durability. Synthesis and characterization of glass, glass paste preparation and its application to spinel substrates to form coating and bonding and optical characterizations in the UV, VIS and IR of coated, uncoated, and bonded spinel substrates of two commercial sources are described. Enhancement of transmittance exceeding the theoretical value of polished spinel was found for the first time when glass coating was applied to a ground face of semi-polished spinel.
Citation: Ceramics
PubDate: 2024-01-25
DOI: 10.3390/ceramics7010008
Issue No: Vol. 7, No. 1 (2024)
- Ceramics, Vol. 7, Pages 115-136: A CFD Analysis of the Desalination
Performance of Ceramic-Based Hollow Fiber Membranes in Direct Contact
Membrane Distillation
Authors: MHD Maher Alrefaai, Mohd Hafiz Dzarfan Othman, Mohammad Rava, Zhong Sheng Tai, Abolfazl Asnaghi, Mohd Hafiz Puteh, Juhana Jaafar, Mukhlis A. Rahman, Mohammed Faleh Abd Al-Ogaili
First page: 115
Abstract: In this numerical study, the performance of ceramic-based mullite hollow fiber (HF) membranes in a direct contact membrane distillation (DCMD) process was evaluated. Three types of membranes were tested: (i) hydrophobic membrane C8-HFM, (ii) rod-like omniphobic membrane (C8-RL/TiO2), and (iii) flower-like omniphobic membrane (C8-FL/TiO2). The CFD model was developed and validated with experimental results, which were performed over a 500 min period. The initial mass flux of C8-HFM was 30% and 9% higher than that of C8-FL/TiO2 and C8-RL/TiO2, respectively. However, the flower-like omniphobic membrane C8-FL/TiO2 had the lowest drop in flux, around 11%, while the rod-like omniphobic membrane C8-RL/TiO2 had a 15% reduction, both better than the 23% reduction in the hydrophobic membrane C8-HFM over the 500 min. The study also analyzed the impact of fouling by examining the variation in mass transfer coefficient (MTC) over time. The results indicated that the ceramic-based mullite HF membranes with TiO2 flowers and rods demonstrated a high resistance to fouling compared to C8-HFM. The modified membranes could find applications in the desalination and handling of seawater samples containing organic contaminants. The CFD model’s versatility can be utilized beyond the current investigation’s scope, offering a valuable tool for efficient membrane development solutions, particularly for challenges such as the presence of organic contaminants in seawater.
Citation: Ceramics
PubDate: 2024-01-26
DOI: 10.3390/ceramics7010009
Issue No: Vol. 7, No. 1 (2024)
- Ceramics, Vol. 7, Pages 137-165: Archaeometric Investigations on
Archaeological Findings from Palazzo Corsini Alla Lungara (Rome)
Authors: Tilde de Caro, Fiammetta Susanna, Paola Fraiegari, Renato Sebastiani, Veronica Romoli, Simone Bruno, Andrea Macchia
First page: 137
Abstract: This study reports the analytical investigations on clayey and ceramic finds, characterised by high variability in terms of prime materials, with the aim to determine the role of this important ceramic production situated close to the city walls, fortuitously found during service excavations developed in the garden of Palazzo Corsini in Rome. The complexity of the finds led to the choices of appropriate methodologies and techniques suitable for defining the diagnostic elements of each find. Optical microscopy (OM) combined with micro-Raman (µ-Raman) spectroscopy, X-ray diffractometry (XRD), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM/EDS), and differential thermal analysis (DTA) were used to analyse the nature and microstructure of the ceramic and burned clay that were found. In such a complicated setting, the objective of conducting chemical analyses is to provide clues to describe the various kinds of ceramics produced, the production and processing methods, and, as a result, the typology of the workshop.
Citation: Ceramics
PubDate: 2024-01-30
DOI: 10.3390/ceramics7010010
Issue No: Vol. 7, No. 1 (2024)
- Ceramics, Vol. 7, Pages 166-191: Effect of Binder on Oxidation Properties
of Tungsten Carbides: A Review by a Conceptual Classification Approach
Authors: Zahra Fathipour, Morteza Hadi, Mohammad Reza Maleki, Filipe Fernandes
First page: 166
Abstract: This study presents a conceptual classification scheme to review the literature on improving the oxidation resistance of tungsten carbide by modifying the binder. The first parts of the article are dedicated to the specification of the databases, the search method, and the description of the criteria chosen to classify the articles. Then, the data collected are presented in statistical graphs according to the proposed classification scheme. The data analyzed show that most of the significant improvements in oxidation resistance are achieved with advanced production processes, especially HIP and SPS, which eliminate porosity to a very high degree. In addition, statistical studies showed that the use of new replacement binders, Ni3Al, Fe–based alloys, FeAl, and Al2O3, improved the oxidation properties in 75–100% of cases. Meanwhile, the use of high–entropy alloys (HEAs) as cermet binders may be the subject of future research for oxidation, given the recently published results of good mechanical properties.
Citation: Ceramics
PubDate: 2024-01-31
DOI: 10.3390/ceramics7010011
Issue No: Vol. 7, No. 1 (2024)
- Ceramics, Vol. 7, Pages 192-207: Plasma Actuators Based on Alumina
Ceramics for Active Flow Control Applications
Authors: Frederico F. Rodrigues, Kateryna O. Shvydyuk, João Nunes-Pereira, José C. Páscoa, Abílio P. Silva
First page: 192
Abstract: Plasma actuators have demonstrated great potential for active flow control applications, including boundary layer control, flow separation delay, turbulence control, and aircraft noise reduction. In particular, the material used as a dielectric barrier is crucial for the proper operation of the device. Currently, the variety of dielectrics reported in the literature is still quite restricted to polymers including Kapton, Teflon, poly(methyl methacrylate) (PMMA), Cirlex, polyisobutylene (PIB) rubber, or polystyrene. Nevertheless, several studies have highlighted the fragilities of polymeric dielectric layers when actuators operate at significantly high-voltage and -frequency levels or for long periods. In the current study, we propose the use of alumina-based ceramic composites as alternative materials for plasma actuator dielectric layers. The alumina composite samples were fabricated and characterized in terms of microstructure, electrical parameters, and plasma-induced flow velocity and compared with a conventional Kapton-based actuator. It was concluded that alumina-based dielectrics are suitable materials for plasma actuator applications, being able to generate plasma-induced flow velocities of approximately 4.5 m/s. In addition, it was verified that alumina-based ceramic actuators can provide similar fluid mechanical efficiencies to Kapton actuators. Furthermore, the ceramic dielectrics present additional characteristics, such as high-temperature resistance, which are not encompassed by conventional Kapton actuators, which makes them suitable for high-temperature applications such as turbine blade film cooling enhancement and plasma-assisted combustion. The high porosity of the ceramic results in lower plasma-induced flow velocity and lower fluid mechanical efficiency, but by minimizing the porosity, the fluid mechanical efficiency is increased.
Citation: Ceramics
PubDate: 2024-02-06
DOI: 10.3390/ceramics7010012
Issue No: Vol. 7, No. 1 (2024)
- Ceramics, Vol. 7, Pages 208-221: Optical and Spectroscopic Properties of
Ho:Lu2O3 Transparent Ceramics Elaborated by Spark Plasma Sintering
Authors: Lucas Viers, Simon Guené-Girard, Gilles Dalla-Barba, Véronique Jubéra, Éric Cormier, Rémy Boulesteix, Alexandre Maître
First page: 208
Abstract: In this work, transparent ceramics were manufactured from nanopowders synthesized by aqueous coprecipitation followed by Spark Plasma Sintering (SPS) to ensure rapid and full densification. The photoluminescence of Ho:Lu2O3 transparent ceramics was studied in the Visible and IR domains as a function of Ho3+ dopant level from 0.5 at.% to 10 at.%. A cross-relaxation mechanism was identified and favors the 2 μm emission. All of the obtained results indicate that the optical properties are very similar between Lu2−xHoxO3 transparent ceramics and single crystals. Thus, the SPS technique appears to be a very promising method to manufacture such ceramics, which could be used as amplifier media for high-energy solid-state lasers.
Citation: Ceramics
PubDate: 2024-02-08
DOI: 10.3390/ceramics7010013
Issue No: Vol. 7, No. 1 (2024)
- Ceramics, Vol. 7, Pages 222-234: Influence of Non-Invasive Zirconium Oxide
Surface Treatment on Phase Changes
Authors: Kinga Regulska, Bartłomiej Januszewicz, Anna Jędrzejczak, Leszek Klimek
First page: 222
Abstract: The aim of the research was to find a zirconia treatment method that would reduce or minimize the transformation from the tetragonal phase to the monoclinic phase. Background: Yttria-stabilized zirconia is increasingly chosen for the base of permanent prosthetic restorations. To achieve a good bond between the prosthetic cup and the veneer material, the material must be treated to achieve surface development. This is a mechanical process, during which an unfavorable transformation from the tetragonal into the monoclinic phase takes place, which leads to the weakening of the internal structure of zirconium dioxide, and later damages the prosthetic restoration. Methods: The tested material consisted of cylindrical samples of 3Y-TZP CeramillZi zirconium oxide, which were sintered after cutting out from the block. After sintering, the samples were subjected to the following types of processing: laser structuring, chemical etching and plasma etching. After the surface treatments, the samples were subjected to diffraction tests to determine the phase composition. Next, the wettability was tested to determine the surface free energy. Results: On the basis of the conducted tests, it was noticed that the applied treatments caused a phase transformation from the tetragonal to the monoclinic phase. After the process of chemical etching, the range of the monoclinic phase for the sample was 5%; after plasma etching, it was 8%, and after laser structuring, it was 2%. In addition, post-surface free energy studies have shown that zirconia is wetted better with an apolar than a polar liquid. Conclusions: The obtained results indicate that the transformation was minimized with the treatments we applied; that is why they are called non-invasive methods. According to the literature data, depending on the parameters of the sandblasting process, the percentage of the monoclinic phase in the treated surfaces ranges from 22% to 52%, which confirms the above-mentioned conclusion.
Citation: Ceramics
PubDate: 2024-02-08
DOI: 10.3390/ceramics7010014
Issue No: Vol. 7, No. 1 (2024)
- Ceramics, Vol. 7, Pages 235-249: Temperature-Dependent Elastic Properties
of B4C from First-Principles Calculations and Phonon Modeling
Authors: Sara Sheikhi, Wylie Stroberg, James D. Hogan
First page: 235
Abstract: Boron carbide plays a crucial role in various extreme environment applications, including thermal barrier coatings, aerospace applications, and neutron absorbers, because of its high thermal and chemical stability. In this study, the temperature-dependent elastic stiffness constants, thermal expansion coefficient, Helmholtz free energy, entropy, and heat capacity at a constant volume (Cv) of rhombohedral B4C have been predicted using a quasi-harmonic approach. A combination of volume-dependent first-principles calculations (density functional theory) and first-principles phonon calculations in the supercell framework has been performed. Good agreement between the elastic constants and structural parameters from static calculations is observed. The calculated thermodynamic properties from phonon calculations show trends that align with the literature. As the temperature rises, the predicted free energy follows a decreasing trend, while entropy and Cv follow increasing trends with temperature. Comparisons between the predicted room temperature thermal expansion coefficient (TEC) (7.54×10−6 K−1) and bulk modulus (228 GPa) from the quasi-harmonic approach and literature results from experiments and models are performed, revealing that the calculated TEC and bulk modulus fall within the established range from the limited set of data from the literature (TEC = 5.73–9.50 ×10−6 K−1, B = 221–246 GPa). Temperature-dependent Cijs are predicted, enabling stress analysis at elevated temperatures. Overall, the outcomes of this study can be used when performing mechanical and thermal stress analysis (e.g., space shielding applications) and optimizing the design of boron carbide materials for elevated temperature applications.
Citation: Ceramics
PubDate: 2024-02-21
DOI: 10.3390/ceramics7010015
Issue No: Vol. 7, No. 1 (2024)
- Ceramics, Vol. 7, Pages 250-263: Mussel-Inspired Construction of
Silica-Decorated Ceramic Membranes for Oil–Water Separation
Authors: Qibo Zhou, Qibing Chang, Yao Lu, Jing Sun
First page: 250
Abstract: In recent years, ceramic membranes have received widespread focus in the area of liquid separation because of their high permeability, strong hydrophilicity, and good chemical stability. However, in practical applications, the surface of ceramic membranes is prone to be contaminated, which degrades the permeation flux of ceramic membranes during the separation process. Inspired by mussels, we imitate the biomimetic mineralization process to prepare a ceramic membrane of nano–silica on the pre-modified zirconia surface by co-deposited polydopamine/polyethyleneimine. The modified ceramic membranes were utilized for the purpose of oil–water separation. Separation performance has been tested using a disc ceramic membrane dynamic filtration device. The outcomes revealed an enhanced permeability in the modified membrane, measuring as 159 L m−2 h−1 bar−1, surpassing the separation flux of the unmodified membrane, which was 104 L m−2 h−1 bar−1. The permeation performance of the modified membrane was increased to 1.5 times. Modified ceramic membranes are highly resistant to fouling. From the beginning to the end of separation process, the oil rejection rate of the modified ceramic membrane is always higher than 99%. After a 2 h oil–water separation test run, modified ceramic membrane permeate flux can be restored to 91% after cleaning. It has an enormous capacity for application in the area of oil–water separation.
Citation: Ceramics
PubDate: 2024-02-22
DOI: 10.3390/ceramics7010016
Issue No: Vol. 7, No. 1 (2024)
- Ceramics, Vol. 7, Pages 264-275: Use of Ultra-Translucent Monolithic
Zirconia as Esthetic Dental Restorative Material: A Narrative Review
Authors: Ghada Alrabeah, Abdulrahman H. Al-Sowygh, Samaher Almarshedy
First page: 264
Abstract: It has been observed in recent years that zirconia (Zr) is being increasingly used for a wide range of clinical applications. There are several reasons for this, but the most significant one is its excellent mechanical properties, specifically its transformation toughening properties compared to other dental ceramics and its improved natural appearance when compared to ceramometal restorations. As a result of the advancement of chairside milling and developments in rapid-sintering technology, the fabrication of dental restorations has become more computerized, time-saving, and accurate over the past few decades. However, a main disadvantage of conventional Zr restorations is that they lack the translucency of glass–ceramics, although they are extremely strong. Recently, by increasing the yttrium %, changing the grain size, and reducing the impurities, the ultra-translucent monolithic zirconia “5-mol%-yttria-stabilized tetragonal zirconia polycrystals” has been introduced, with successful attempts to make translucent Zr an aesthetically attractive option for minimally invasive veneer restorations. It is important to note that veneer restorations do not possess the mechanical retentive features of the tooth preparations and rely primarily on bonding to resin cement. This presents a great challenge for the inert Zr since it does not bond chemically with resin cement, unlike glass–ceramic materials that establish chemical adhesion with resin cement, favoring their use for indirect veneer restorations. Taking this into account, this article aims to review the progressive development of ultra-translucent monolithic Zr materials as they are available today and, in the future, represents a concerted drive toward maximum translucency and strength, which renders them a viable treatment option for esthetic veneer restorations.
Citation: Ceramics
PubDate: 2024-02-23
DOI: 10.3390/ceramics7010017
Issue No: Vol. 7, No. 1 (2024)
- Ceramics, Vol. 7, Pages 276-290: LiGdxY1−xF4 and LiGdF4:Eu3+
Microparticles as Potential Materials for Optical Temperature Sensing
Authors: Ekaterina I. Oleynikova, Oleg A. Morozov, Stella L. Korableva, Maksim S. Pudovkin
First page: 276
Abstract: In this work, the physical characterization of LiGdxY1−xF4 (x = 0.05, 0.3, 0.7, and 1.0) and LiGdF4:Eu3+ microparticles was performed. The distribution coefficient of LiGdxY1−xF4 (x = 0.05) was determined for the first time (0.84). Based on kinetic characterization data, the LiGdF4 sample was chosen for further Eu3+ doping (0.1 and 1.0 at.%). For the LiGdF4:Eu3+ sample, Eu3+ emission was clearly observed under the excitation of Gd3+. This fact indicates an effective energy transfer from Gd3+ to Eu3+. The temperature-dependent spectral characterization of the LiGdF4:Eu3+ (1.0%) sample revealed that in the 30–250 K temperature range, a broad emission peak is evidenced. Its intensity sharply increases with the temperature decrease. We made a suggestion that this phenomenon is related to the irradiation-induced defects. The integrated luminescence intensity ratio of this broad peak and the Eu3+ emission were taken as temperature-dependent parameters. The sensitivity values are very competitive, and the first maximum occurs at 174 K (3.18%/K). The kinetic characteristics of both Gd3+ and Eu3+ did not demonstrate a notable temperature dependence. The LiGdF4:Eu3+ sample showed the possibility of being used as an optical temperature sensor, operating in the cryogenic temperature range.
Citation: Ceramics
PubDate: 2024-02-23
DOI: 10.3390/ceramics7010018
Issue No: Vol. 7, No. 1 (2024)
- Ceramics, Vol. 7, Pages 291-309: Sustainable Approaches for the Additive
Manufacturing of Ceramic Materials
Authors: Alice Villa, Pardeep Gianchandani, Francesco Baino
First page: 291
Abstract: Additive manufacturing technologies collectively refer to a set of layer-wise deposition methods that typically rely on CAD-CAM approaches for obtaining products with a complex shape/geometry and high precision and reliability. If the additive manufacturing of polymers is relatively easy and scalable due to the low temperatures needed to obtain processable inks, using similar technologies to fabricate ceramic products is indeed more challenging and expensive but, on the other hand, allows for obtaining high-quality results that would not be achievable through conventional methods. Furthermore, the implementation of additive manufacturing allows for the addressing of some important concerns related to the environment and sustainability, including the minimization of resource depletion and waste production/disposal. Specifically, additive manufacturing technologies can provide improvements in energy consumption and production costs, besides obtaining less waste material and less CO2 emissions, which are all key points in the context of the circular economy. After providing an overview of the additive manufacturing methods which are specifically applied to ceramics, this review presents the sustainability elements of these processing strategies, with a focus on both current and future benefits. The paucity of specific available studies in the literature—which are included and discussed in this review—suggests that the research on additive manufacturing sustainability in the field of ceramic materials is in the preliminary stage and that more relevant work still deserves to be carried out in the future to explore this fascinating field at the boundary among ceramics science/technology, production engineering and waste management.
Citation: Ceramics
PubDate: 2024-02-23
DOI: 10.3390/ceramics7010019
Issue No: Vol. 7, No. 1 (2024)
- Ceramics, Vol. 7, Pages 310-328: High-Performance Ceramics in
Musculoskeletal Surgery: Current Use and Future Perspectives
Authors: Jörg Eschweiler, Johannes Greven, Björn Rath, Philipp Kobbe, Ali Modabber, Frank Hildebrand, Filippo Migliorini, Ulf Krister Hofmann
First page: 310
Abstract: Osteoarthritis (OA) is a prevalent disease among the elderly population, necessitating effective treatment options. Total joint arthroplasty (TJA) is a reliable surgical procedure that has shown good long-term clinical outcomes for OA. However, certain challenges, such as implant failure caused by particle-induced aseptic loosening or hypersensitivity to metal ions, remain unresolved in TJA. High-performance ceramic implants have emerged as a promising solution to address these persistent implant-related issues. This review article provides an overview of the composition and characteristics of ceramics used in TJA, highlighting their potential advantages and associated risks. While ceramic implants have demonstrated excellent performance in vivo for hip and knee arthroplasty, their bioinert behaviour is still considered a crucial factor regarding cementless options. Therefore, novel methods are investigated that seem to be able to combine the benefits of ceramic materials with an excellent osseointegration behaviour, which makes ceramics as implant materials an even stronger option for future applications.
Citation: Ceramics
PubDate: 2024-02-23
DOI: 10.3390/ceramics7010020
Issue No: Vol. 7, No. 1 (2024)
- Ceramics, Vol. 7, Pages 329-341: Analysis of the Luminescent Emission
during Flash Sintering of 8YSZ and 20SDC Ceramics
Authors: Reginaldo Muccillo, Julio Cesar C. A. Diaz, Eliana N. S. Muccillo
First page: 329
Abstract: Light-emission data were collected before, during, and after the occurrence of the flash event in pressureless electric-field-assisted (flash) sintering experiments on ZrO2: 8 mol% Y2O3 (8YSZ) and CeO2: 20 mol% Sm2O3 (20SDC) ceramic green pellets to analyze the luminescent emission from the samples. The experiments were performed at 800 °C with an applied electric field of 100 V·cm−1 at 1 kHz, limiting the electric current to 1 A. Luminescence data were obtained in the 200–1200 nm (ultraviolet–visible–near-infrared) range. The deconvolution of the optical spectra allowed for the identification of emission bands in the visible range due exclusively to the samples. The wavelength maxima of the emission bands in 8YSZ were found to be different from those in 20SDC. It is suggested that these bands might originate from the interaction of the electric current, resulting from the application of the electric field, with the depleted species located at the space-charge region at the grain boundaries of these ceramics. The main results represent a contribution to help to clarify the mechanisms responsible for the fast densification with inhibition of grain growth in electroceramics.
Citation: Ceramics
PubDate: 2024-02-25
DOI: 10.3390/ceramics7010021
Issue No: Vol. 7, No. 1 (2024)
- Ceramics, Vol. 7, Pages 342-363: Franklinite-Zincochromite-Gahnite Solid
Authors: Guillermo Monrós, José A. Badenes, Mario Llusar, Carolina Delgado
First page: 342
Abstract: Franklinite-zincochromite-gahnite solid solutions were prepared using ceramic or coprecipitation methods, and their pigmenting capacity as cool ceramic pigments in different glazes (double and single firing frits and porcelain frit) was studied. XRD, UV–Vis–NIR diffuse reflectance, CIEL*a*b* colour analysis, band gap measurements, and the photocatalytic degradation of Orange II were carried out to characterise the samples. The following criteria for high red colouring capacity and high NIR reflectance at the minimum Cr amount were found to be the optimal compositions for an intense reddish cool pigment: Zn(Fe1.8Cr0.2), Zn(Al1.5Cr0.5) and Zn(Al1.3Cr0.5Fe0.2)O4. All the powders showed a direct semiconductor behaviour, with a band gap of approximately 2 eV, which fell in the visible range (620 nm); the visible light photocatalysis of Orange II was moderate, but franklinite-zincochromite Zn(Fe1.8Cr0.2) stood out compared with silver orthophosphate.
Citation: Ceramics
PubDate: 2024-03-01
DOI: 10.3390/ceramics7010022
Issue No: Vol. 7, No. 1 (2024)
- Ceramics, Vol. 7, Pages 364-384: Holistic Characterization of MgO-Al2O3,
MgO-CaZrO3, and Y2O3-ZrO2 Ceramic Composites for Aerospace Propulsion
Systems
Authors: Kateryna O. Shvydyuk, João Nunes-Pereira, Frederico F. Rodrigues, José C. Páscoa, Senentxu Lanceros-Mendez, Abílio P. Silva
First page: 364
Abstract: Aerospace propulsion systems are among the driving forces for the development of advanced ceramics with increased performance efficiency in severe operation conditions. The conducted research focused on the mechanical (Young’s and shear moduli, flexural strength, hardness, and fracture toughness), thermal (thermal conductivity and coefficient of thermal expansion), and electric (dielectric properties) characterization of MgO-Al2O3, MgO-CaZrO3, and stable YSZ ceramic composites. The experimental results, considering structural and functional traits, underscore the importance of a holistic understanding of the multifunctionality of advanced ceramics to fulfill propulsion system requirements, the limits of which have not yet been fully explored.
Citation: Ceramics
PubDate: 2024-03-02
DOI: 10.3390/ceramics7010023
Issue No: Vol. 7, No. 1 (2024)
- Ceramics, Vol. 7, Pages 385-400: Hydrogen Permeation Properties of Ternary
Ni–BaCe0.9Y0.1O3–Ce0.9Gd0.1O2 Cermet Membranes
Authors: Yoshiteru Itagaki, Hiroyuki Mori, Takumi Matsubayashi, Hiromichi Aono
First page: 385
Abstract: A ternary Ni–BaCe0.9Y0.1O3 (BCY)–Ce0.9Gd0.1O2 (GDC) cermet involving 40 vol% Ni was fabricated, and its hydrogen permeation characteristics were evaluated when the GDC volume fraction was varied from 0 to 30 vol%. The X-ray diffraction results of the cermet after sintering at 1400 °C revealed that GDC was dissolved in BCY when the GDC volume composition was 20 vol%. Regardless of the BCY and GDC volume fractions, the metal conductivity of the cermet was dominated by Ni. After the addition of only 1 vol% GDC, the particle sizes of Ni and BCY in the cermet significantly decreased, and the particle size decreased as the volume fraction of GDC increased. The hydrogen permeability increased with increasing temperature and for up to 10 vol% GDC, and a maximum permeation rate of 0.142 mL min−1 cm−2 was obtained at 700 °C. This value is comparable to or better than previously reported values for Ni-cermets under the same conditions. The amount of hydrogen permeation decreased above 10 vol% GDC. This study demonstrated that Ni-BCY-GDC cermet is a material that has both high hydrogen permeability and CO2 resistance.
Citation: Ceramics
PubDate: 2024-03-13
DOI: 10.3390/ceramics7010024
Issue No: Vol. 7, No. 1 (2024)
- Ceramics, Vol. 7, Pages 401-410: Beyond Scanning Electron Microscopy:
Comprehensive Pore Analysis in Transparent Ceramics Using Optical
Microscopy
Authors: Francesco Picelli, Jan Hostaša, Andreana Piancastelli, Valentina Biasini, Cesare Melandri, Laura Esposito
First page: 401
Abstract: Developing an effective method of quantifying defects in the bulk of transparent ceramics is a challenging task that could facilitate their widespread use as a substitute for single crystals. Conventionally, SEM analysis is used to examine the microstructure but it is limited to the material surface. On the other hand, optical transmittance assesses material quality, but does not provide information on the size and concentration of defects. In this study, we illustrate the use of a digital optical microscope for the non-destructive, precise, and rapid analysis of residual porosity in transparent ceramics. YAG-based ceramics doped with Yb have been selected for this study because they are used as laser gain media, an application that requires virtually defect-free components. Different production processes were used to produce YAG samples, and the digital optical microscope analysis was used to compare them. This analysis was shown to be effective and precise to measure the size and concentration of the residual pores. In addition, the comparison of samples obtained with different production processes showed that the size and distribution of the residual porosity is affected by the drying step of the powders before shaping by pressing, as well as by the sintering aids used to ease the densification. It also showed that the transmittance is influenced by both the total volume and the concentration of the pores.
Citation: Ceramics
PubDate: 2024-03-15
DOI: 10.3390/ceramics7010025
Issue No: Vol. 7, No. 1 (2024)
- Ceramics, Vol. 7, Pages 411-425: Structural and Dielectric Properties of
Titania Co-Doped with Yttrium and Niobium: Experimental Evidence and DFT
Study
Authors: Deborah Y. B. Silva, Reginaldo Muccillo, Eliana N. S. Muccillo
First page: 411
Abstract: This work explores the impact of the sintering temperature and co-dopant contents on the microstructure and dielectric properties of (Y0.5Nb0.5)xTi1−xO2 (0.025 ≤ x ≤ 0.10) ceramics synthesized by the solid state reaction method. The physical mechanism underlying the colossal electric permittivity was systematically investigated with experimental methods and first principles calculations. All specimens exhibited the characteristic tetragonal structure of rutile, besides secondary phases. A niobium- and yttrium-rich secondary phase emerged at the grain boundaries after heating at 1500 °C, changing the main sintering mechanism. The highest value of the electric permittivity (13499 @ 60 °C and 10 kHz) was obtained for (Y0.5Nb0.5)0.05Ti0.95O2 sintered at 1480 °C, and the lowest dissipation factor (0.21@ 60 °C and 10 kHz) for (Y0.5Nb0.5)0.1Ti0.90O2 sintered at 1500 °C. The dielectric properties of Y3+ and Nb5+ co-doped TiO2 are attributed to the internal barrier layer capacitance (IBLC) and electron-pinned dipole defect (EPDD) mechanisms.
Citation: Ceramics
PubDate: 2024-03-17
DOI: 10.3390/ceramics7010026
Issue No: Vol. 7, No. 1 (2024)
- Ceramics, Vol. 7, Pages 426-435: Effects of Replacing Co2+ with Zn2+ on
the Dielectric Properties of Ba [Zn1/3(Nb1/2Ta1/2)2/3]O3 Ceramics with
High Dielectric Constant and High Quality Factor
Authors: Yuan-Bin Chen, Yu Fan, Shiuan-Ho Chang, Shaobing Shen
First page: 426
Abstract: In this study, we used solid-state synthesis to prepare Ba[(ZnxCo1−x)1/3(Nb0.5Ta0.5)2/3]O3 microwave ceramics for mobile communications. Compared with Ba[Zn1/3(Nb0.5Ta0.5)2/3]O3, in the prepared materials, Co2+ substitution with Zn2+ improved the Q × f value and enabled densification and sintering at a lower temperature. We used X-ray diffraction (XRD) and scanning electron microscopy (SEM) to analyze the obtained microstructure. Ba[(ZnxCo1−x)1/3(Nb0.5Ta0.5)2/3]O3 was found to have a 1:2 ordered hexagonal structure, and its Q × f value increased with the increase in sintering temperature. In this work, excellent microwave dielectric properties—τf = −0.7 ppm/°C, εr = 34.5, and Q × f = 110,000 GHz—were obtained by sintering Ba[(Zn0.3Co0.7)1/3(Nb0.5Ta0.5)2/3]O3 at 1400 °C for 5 h.
Citation: Ceramics
PubDate: 2024-03-17
DOI: 10.3390/ceramics7010027
Issue No: Vol. 7, No. 1 (2024)
