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The search for a high- κ dielectric material that combines a high dielectric constant (ϵ ′ ) and low dielectric loss is very crucial because of its widespread use in gate dielectrics to avoid the leakage current that arises due to continued miniaturization of present SiO 2 -based metal-oxide semiconductor field-effect transistor devices. RCrO 3 (R is a rare-earth ion) materials have been at the center of interest because of their intriguing ferroelectric and magnetic properties, as well as their room-temperature colossal dielectric constant (CDC) values. Although CDC (ϵ ′ ∼ 10 4) in RCrO 3 materials is quite common, it is unsuitable for device applications since it is associated with a larger dielectric loss value (tan δ ∼ 7 at 11 kHz). Here we have focused on polycrystalline DyCrO 3 , prepared using multiple synthesis techniques, and thoroughly investigated the origin and tuning of the various dielectric relaxations that give rise to CDC and large dielectric loss values. A clear understanding of the origin of dielectric relaxations enables us to design a specially synthesized DyCrO 3 (SPS-DCO) in which the extrinsic dielectric relaxations driven large dielectric loss values can be completely suppressed and which is found to be associated with optimized high- κ dielectric properties [ ϵ ′ ∼ 130 , tan δ ∼ 0.06 , and temperature coefficient of dielectric constant (TC ϵ) ∼ 2280 ppm/K at 11 kHz, 300 K]. The only remaining intrinsic Debye-type dielectric relaxation in SPS-DCO arises due to electric-field-assisted charge hopping among various valences of Cr (investigated using x-ray photoelectron spectroscopy) that presently limits the lowest attainable loss value. [ABSTRACT FROM AUTHOR]

Silicon carbide (SiC) ceramic stands as a critical material in the realm of high-performance engineering ceramics. However, Crafting SiC ceramics with intricate structures and superior mechanical properties presents notable challenges in shaping, sintering, and processing. Binder jetting (BJ) additive manufacturing has the outstanding advantages of high forming efficiency and no thermal deformation, especially suitable for printing complex structure SiC components.; however, BJ printed green bodies often exhibit low density, resulting in high residual silicon content and diminished strength of the final components. In this work, we introduce a novel strategy to fabricate high-strength SiC components with complex geometries by improving the density of printed SiC green bodies. This method involves modifying the morphology of SiC powder through the molten salt method to increase the density of BJ 3D printed green bodies from 1.24 ± 0.13 g/cm³ to 2.01 ± 0.03 g/cm³, followed by a reactive melt infiltration process. The resulting RB-SiC ceramics display exceptional flexural strength, averaging 280.60 ± 33.05 MPa, and an elastic modulus of 294.67 ± 4.90 GPa. These values represent some of the highest for flexural strength and elastic modulus reported among 3D-printed SiC composites. With its robust mechanical performance and streamlined fabrication process, this strategy holds substantial promise for the production of structural SiC ceramics. [ABSTRACT FROM AUTHOR]

A powder compact with anion‐uptake ability was prepared prior to the proceeding of the solid‐state reaction involving layered double hydroxide (LDH) and kaolinite during calcination. LDH features anion‐exchangeable capability, and kaolinite is used as a raw potty material because of the sintering property. In the present study, the solid‐state reaction of LDH with kaolinite did not proceed at 750°C, resulting in the formation of a mixture of layered double oxide (LDO) and metakaolinite. Unlike LDO, which typically undergoes anion‐uptake accompanied by LDH reconstruction, metakaolinite does not revert to kaolinite without the use of hydrothermal conditions. In addition, the powder compact composed of LDO crumbled, whereas the one containing a mixture of LDO and metakaolinite remained intact. When the powder compact of LDO and metakaolinite mixture was immersed in a methyl orange (MO) aqueous solution, an LDH–MO intercalation compound was generated within the compact. By contrast, no such compound was generated when LDO powder was immersed in an MO aqueous solution. These results indicated that the successful preparation of a powder compact with distinct anion‐uptake ability was different from powder, owing to that the solid‐state reaction of LDO with metakaolinite did not proceed at 750°C. [ABSTRACT FROM AUTHOR]

Unlike metals where dislocations carry strain singularity but no charge, dislocations in oxide ceramics are characterized by both a strain field and a local charge with a compensating charge envelope. Oxide ceramics with their deliberate engineering and manipulation are pivotal in numerous modern technologies such as semiconductors, superconductors, solar cells, and ferroics. Dislocations facilitate plastic deformation in metals and lead to a monotonous increase in the strength of metallic materials in accordance with the widely recognized Taylor hardening law. However, achieving the objective of tailoring the functionality of oxide ceramics by dislocation density still remains elusive. Here a strategy to imprint dislocations with {100}<100> slip systems and a tenfold change in dislocation density of BaTiO3 single crystals using high‐temperature uniaxial compression are reported. Through a dislocation density‐based approach, dielectric permittivity, converse piezoelectric coefficient, and alternating current conductivity are tailored, exhibiting a peak at medium dislocation density. Combined with phase‐field simulations and domain wall potential energy analyses, the dislocation‐density‐based design in bulk ferroelectrics is mechanistically rationalized. These findings may provide a new dimension for employing plastic strain engineering to tune the electrical properties of ferroics, potentially paving the way for advancing dislocation technology in functional ceramics. [ABSTRACT FROM AUTHOR]

Unlike metals where dislocations carry strain singularity but no charge, dislocations in oxide ceramics are characterized by both a strain field and a local charge with a compensating charge envelope. Oxide ceramics with their deliberate engineering and manipulation are pivotal in numerous modern technologies such as semiconductors, superconductors, solar cells, and ferroics. Dislocations facilitate plastic deformation in metals and lead to a monotonous increase in the strength of metallic materials in accordance with the widely recognized Taylor hardening law. However, achieving the objective of tailoring the functionality of oxide ceramics by dislocation density still remains elusive. Here a strategy to imprint dislocations with {100}<100> slip systems and a tenfold change in dislocation density of BaTiO3 single crystals using high‐temperature uniaxial compression are reported. Through a dislocation density‐based approach, dielectric permittivity, converse piezoelectric coefficient, and alternating current conductivity are tailored, exhibiting a peak at medium dislocation density. Combined with phase‐field simulations and domain wall potential energy analyses, the dislocation‐density‐based design in bulk ferroelectrics is mechanistically rationalized. These findings may provide a new dimension for employing plastic strain engineering to tune the electrical properties of ferroics, potentially paving the way for advancing dislocation technology in functional ceramics. [ABSTRACT FROM AUTHOR]

In industrial practice, combining grain growth inhibitors (GGIs) with low carbon content effectively restrains WC grain growth in WC-Co cemented carbides. However, the intricate relationship between carbon content, WC grain microstructure, and GGI impact remains unresolved. This study investigates two WC-Co sample sets, maintaining constant VC inhibitor levels but varying carbon content near upper (HC) and lower (LC) limits. SEM analysis revealed distinct morphologies: HC displayed truncated prism shapes, exposing long basal and prismatic terraces, while LC exhibited a saw-tooth morphology with finer grains. EBSD stereology quantified anisotropic WC grain growth, revealing suppressed growth perpendicular to both basal (HC: 0.51 μm vs. LC: 0.38 μm) and prismatic planes (HC: 0.44 μm vs. LC: 0.37 μm) with decreased carbon content. Atomic-resolution EDS showed higher V solute excess in LC at WC(basal)-Co, WC(prismatic)-Co interfaces, and step corners (HC: 4.6, 0.9, and 4.4 atoms/nm2; LC: 5.5, 0.9, and 7.8 atoms/nm2). Our findings elucidate a clear physical understanding that a low carbon content enhances V atom solubility within liquid cobalt, increasing the thickness of complexions to quad-layer on WC (basal)-Co interfaces and forming V-rich nanoprecipitates at step corners. Those inhibitory effects further limited step flow, resulting in pronounced step bunching and a saw-tooth fine-grained morphology in LC sample. This study highlights that complexions housing more inhibitory solute elements exert a stronger drag effect on grain growth front migration. This approach has the potential for studying grain growth in anisotropic materials, highlighting the importance of constructing experimental complexion diagrams in engineering fine-structured ceramics and metals. [ABSTRACT FROM AUTHOR]

Extremely reliable and wear‐resistant components are required for subsea pump applications. For this purpose, materials and components were developed and qualified within the framework of a joint project1, which under media lubrication with water containing particles, exhibit the highest possible wear resistance and can thus achieve the longest possible service life. The developed SiC‐bonded diamond ceramics have diamond contents of up to 60 % by volume and can be manufactured in the form of a solid material or as graded components containing diamonds only in the tribologically stressed areas. The results show that the investigated diamond‐containing ceramics are very suitable for media‐lubricated sliding bearings and mechanical seals in subsea applications. The friction values under media lubrication are very stable and independent of tribological loads. In mechanical seal application, SiC‐bonded diamond shows significantly better friction performance than the reference material SiC. An outlook is given on demonstrator tests that are currently in preparation. [ABSTRACT FROM AUTHOR]

This study focuses on the design, additive manufacturing, and characterization of silicon carbide‐based components with complex geometries. These parts were produced using a novel hybrid technique, previously developed: powder bed fusion of polyamide was used to 3D print two different templates with complex architectures. Preceramic polymer infiltrations and pyrolysis with polycarbosilane and furan resin were performed to obtain the ceramic parts. The final densification was achieved with reactive or nonreactive silicon infiltrations according to four different strategies, producing ceramics comprised of crystalline βSiC, reaction‐bonded βSiC, and low residual silicon. The final gyroid samples (∼70 vol% macroporosity) exhibited a maximum compressive strength of 24.7 ± 2.2 MPa, with a skeleton density of 3.173 ± 0.022 g/cm3, and a relative density of 0.935 ± 0.016. These findings underscore the potential of this manufacturing approach and showcase its effectiveness in fabricating intricate ceramic structures for engineering applications as heat exchangers and catalytic supports. [ABSTRACT FROM AUTHOR]

Additive manufacturing has emerged as a transformative tool in biomedical engineering, offering precise control over scaffold design for bone tissue engineering and regenerative medicine. While much attention has been focused on optimizing pore-based scaffold architectures, filament-based microarchitectures remain relatively understudied, despite the fact that the majority of 3D-printers generate filament-based structures. Here, we investigated the influence of filament characteristics on bone regeneration outcomes using a lithography-based additive manufacturing approach. Three distinct filament-based scaffolds (Fil050, Fil083, and Fil125) identical in macroporosity and transparency, crafted from tri-calcium phosphate (TCP) with varying filament thicknesses and distance, were evaluated in a rabbit model of bone augmentation and non-critical calvarial defect. Additionally, two scaffold types differing in filament directionality (Fil and FilG) were compared to elucidate optimal design parameters. Distance of bone ingrowth and percentage of regenerated area within scaffolds were measured by histomorphometric analysis. Our findings reveal filaments of 0.50 mm as the most effective filament-based scaffold, demonstrating superior bone ingrowth and bony regenerated area compared to larger size filament (i.e., 0.83 mm and 1.25 mm scaffolds). Optimized directionality of filaments can overcome the reduced performance of larger filaments. This study advances our understanding of microarchitecture's role in bone tissue engineering and holds significant implications for clinical practice, paving the way for the development of highly tailored, patient-specific bone substitutes with enhanced efficacy. [ABSTRACT FROM AUTHOR]

BaTiO 3 -based ceramic is considered to be a fascinating dielectric material with high reliability for ultra-thin multilayer ceramic capacitors (MLCC). Here, we fabricated a series of acceptor-doped BaTiO 3 (Mg: 0.2, 0.5, 1.0, 1.5, 2.0, and 5.0 mol%) ceramics with Al 2 O 3 and SiO 2 as sintering additives. With an increase in Mg concentration, the insulation resistance of the BaTi 1- x Mg x O 3 ceramics initially increases and then decreases, in which the 0.5 mol% Mg-doped ceramic achieves superior degradation behavior. The reason is that with the incorporation of the acceptor ion Mg2+, the charge compensation mechanism in the system changes. Initially, barium vacancy is generated, which is gradually dominated by oxygen vacancy. Analysis indicates that the segregation of the acceptor state barium vacancy to the grain boundary increases the schottky barrier of the grain boundary, while the gradual increase of the donor state oxygen vacancy reduces the reliability of the ceramic. This study provides a comprehensive overview illustrating the significant role of point defects in the potential barrier of the grain boundary in acceptor-doped BaTiO 3 ceramics. It identifies a pathway to achieve high reliability in BaTiO 3 -based MLCC. [ABSTRACT FROM AUTHOR]

The development of low-temperature solid oxide fuel cells (LT-SOFCs) is gaining abundant interest in semiconductor ionic materials (electrodes and electrolytes). Following this concept, an A-site deficiency technique is employed to unilaterally change BaTiO 3 to regulate ionic conduction, further improving the electrolyte's performance. The electrolytes, namely BaTiO 3 , Ba 0·95 TiO 3 , and Ba 0·90 TiO 3 , have carefully been constructed and studied utilizing solid-state ball milling. The A-site deficiency in BaTiO 3 resulted to improve the ionic conductivity and minimize activation energy. This can be attributed to the higher number of oxygen vacancies on the surface and at the interfaces. The enhanced morphology, direct visualization of lattice structures, and the existence of oxygen vacancies caused by A-site deficiency have been studied in detail. Out of all the prepared electrolytes, Ba 0·90 TiO 3 shows an enhanced fuel cell performance of 625 mW/cm2. In comparison, the Ba 0·95 TiO 3 achieved a reasonable fuel cell performance of 573 mW/cm2, and BaTiO 3 achieved 548.40 mW/cm2 at a low temperature of 550 °C. Compensating for the lack of A-site ions is a successful approach to improve ion transportation in fuel cells without creating any leakage of electric current. This is achieved by modifying the arrangement of energy bands that control the movement of charge carriers. The results of this work demonstrate that A-site-deficiency engineering can be used to improve the electrolyte performance of LT-SOFCs, making it a promising method for advancing fuel cell technologies in the future. [Display omitted] [ABSTRACT FROM AUTHOR]

The large piezoelectric coefficient (d 33) and high mechanical quality factor (Q m) are essential for piezoelectric ceramics used in high-power devices. It is pity that the two parameters are usually opposite, with higher d 33 corresponding to lower Q m. In order to well-balance the d 33 and Q m , the rare-earth element Ce with multi-valence was introduced into the 0.06 Pb(Sc 1/2 Nb 1/2)O 3 -0.61 Pb(Mg 1/3 Nb 2/3)O 3 -0.33PbTiO 3 (x Ce-PSN-PMN-PT) ceramics in this work. The structure, electrical properties and optical properties of ceramics were systematically analyzed. Optimal electrical performances (d 33 = 719 pC/N, Q m = 256, and dielectric loss tan δ = 0.007) were obtained in 0.02Ce-PSN-PMN-PT ceramics. These excellent performances originate from the multiscale coordination effects among defect dipoles, local structural heterogeneity, domain structure, phase structure, and grain size. The x Ce-PSN-PMN-PT ceramics exhibit excellent photoluminescence properties in the blue wavelength range. Our research provides a new paradigm for deep-sea electro-optical communication. [ABSTRACT FROM AUTHOR]

Binary CaO‐MgO‐Al2O3‐SiO2 (CMAS) ceramics composites of anorthite‐cordierite composition were synthesized from natural raw materials (kaolin and dolomite rock). The change of SiO2/Al2O3 ratio in kaolin/dolomite mixtures (12, 24, and 36 wt.%) and synthesized composites along with analysis of their phase composition transformations (X‐ray diffraction) during heat treatment (thermogravimetric and differential thermal analysis) give the controlled design of aluminosilicate matrices. The obtained ceramic composites are represented by anorthite, a cordierite‐like phase whose ratio varies from 1.3:1 to 2.8:1. Mullite crystals, also included in the composition, reinforce the anorthite‐cordierite matrix. The morphostructural features of the samples were studied using optical and scanning electron microscopy. The porosity ranges from 7.8% to 24.2% depending on dolomite content. The impurities of iron and titanium interfering with obtaining a qualitative product are leveled by the presented technique including the heat treatment scheme justified by thermogravimetric analysis. Obtained CMAS‐ceramics of anorthite‐cordierite composition correspond to industrial international standards by their technical characteristics and exceed the requirements for heat‐insulating and chemically resistant materials by compressive strength. [ABSTRACT FROM AUTHOR]

This study investigates spatially resolved phonon-mediated thermal transport across nano-sized grains and grain boundaries (GBs) in 3C-SiC using molecular dynamics (MD) simulations. This investigation involves controlling the complete range of inter-grain misorientation tilt angles (θ = 0°–90°) and nanoscale grain sizes (d = 2.18–130.77 nm). The grain boundary energy and interfacial thermal transport are found to be highly θ -sensitive and asymmetric with respect to θ = 45° due to the low symmetry associated with two interpenetrating diatomic SiC fcc lattices. When adjacent grains are tilted at θ = 14.25°, the interfacial heat conduction is highly suppressed compared to other θ values, especially for larger grains. The most stable atomic configuration of the GB region associated with the minimal GB energy results in the highest suppression of heat conduction across the GB interface. Spatially resolved thermal anisotropy reveals a strong GB-mediated nanoscale hydrodynamic phonon Poiseuille effect when heat flows parallel to the GB planes, as shown by our perturbed MD study. With the reduction of d , the intra-grain and inter-GB thermal conductivities decrease due to the enhanced phonon scattering from interfaces, but the difference between these conductivities becomes negligible for the heat flow normal to the GB planes. It is envisioned that nanoscale spatially resolved control of thermal energy will provide useful guidance to engineer nanocrystalline ceramics with tunable interfacial thermal properties. [ABSTRACT FROM AUTHOR]

The rare-earth orthoferrite perovskite high-entropy ceramics constitute a recently discovered class of high-entropy oxides featuring single-phase structures. However, the practical application of rare-earth orthoferrite high-entropy ceramics is impeded by high dielectric loss and conductivity. Here, rare-earth orthoferrite high-entropy ceramics Bi 0.2 La0 0.2 Y 0.2 Dy 0.2 Tb 0.2 Fe 1-x Ti x O 3 (x = 0, 0.025, 0.05, and 0.075) were fabricated using the conventional solid-phase method. The ceramic with x = 0.025 shows a reduction in grain size and higher electrical resistivity (256 kΩ). Furthermore, an increase in capacitances at grain boundaries is reported in ceramics with x values exceeding 0.025. The results show that donor doping introduces the presence of free electrons, subsequently enhancing polarization at grain boundaries. This non-equimolar high-entropy approach contributes to a deeper understanding of the unique properties exhibited by rare-earth orthoferrite high-entropy materials. [Display omitted] [ABSTRACT FROM AUTHOR]

In recent years, ceramic membranes have been increasingly used in membrane bioreactors (MBRs). However, membrane fouling was still the core issue restricting the large‐scale engineering application of ceramic MBRs. As a novel and alternative technology, ultrasonic could be used to control membrane fouling. This research focused on the efficiency and mechanism of ultrasonic controlling membrane fouling in ceramic MBRs. The results showed that ultrasonic reduced the sludge concentration in MBR, and the average particle size of sludge was always in a high range. The sludge activity of the system was stable at 6–9 (mg O2·(g MLSS·h)−1), indicating that ultrasonic did not destroy the activity of microorganisms in the system. The extracellular polymer substance (EPS) of the ultrasonic group was slightly higher than that of the control group, while the soluble microbial product (SMP) content was relatively stable. The ceramic membrane of the ultrasonic group has a partial retention effect on the organic components. The application of ultrasonic slowed down the decrease of the hydrophilicity of the ceramic membrane. The main pollutants on the membrane surface exist in the form of aromatic and heteroaromatic rings, alkynes, and so forth. Ultrasonic removes the amide substances from the membrane surface. Membrane fouling resistance is mainly due to membrane pore blockage, accounting for 75.53%. Practitioner Points: Enrich the research on the mechanism of ultrasonic technology in membrane fouling control.The MBR can still operate normally with ultrasonic applied.The time for the ceramic membrane to reach the fouling end point is 2.4 times that without ultrasonic.The main cause of membrane fouling was pore blocking, accounting for 75.53%. [ABSTRACT FROM AUTHOR]

It has long been known that dislocations can be used to tune the functional and mechanical properties of ceramics. However, introducing dislocations with controllable networks and densities into ceramics is difficult. In this study, a mechanical rolling techniquewas proposed to introduce dislocations into ceramics. Using a hard SiC ball with a diameter of 5 mm as a roller, plastic zones and dislocations were successfully produced in a SrTiO3 (STO) single crystal. The plastic zone area and dislocation densities were determined by the applied force (F) and number of rolling cycles. A force of 10 N produced a scalable plastic zone with an area of 140 µm x 5000 µm without crack formation after 100 rolling cycles. The dislocation density at the center of the plastic deformation zone can reach ~1014 m², which is an order of magnitude higher than that achieved previously by others. Increasing the applied force increased the density of the introduced dislocations, for example, ~2 x 1014 m-2 under F = 30 and 35 N, however, lead to crack nucleation in the sample. The dislocations introduced significantly enhanced the mechanical properties of the STO crystal. The measured Vickers' hardness and fracture toughness increased by 55%-60% and 23%-24%, respectively, compared to the crystal before rolling. This method can serve as a robust technique for engineering dislocations in ceramics, fulfilling the requirements of dislocation-tuned mechanical and functional investigations. [ABSTRACT FROM AUTHOR]

The design of three‐dimensional (3D)‐printed heterogeneous ceramics exhibiting isotropic and anisotropic dielectric permittivities at microwave frequencies is studied for dielectric resonator antenna (DRA) applications. The heterogeneous ceramics are engineered by using periodic structures made up of subwavelength unit cells filled with zirconia ceramic and air. Ceramic stereolithography (CSLA) allows the 3D printing of a one‐piece ceramic block mixing isotropic and anisotropic dielectric regions. In order to demonstrate the possibility of exploiting such 3D‐printed ceramics, a singly fed dual‐band circularly polarised DRA is presented. To achieve circular polarisation at both bands, the relative permittivity of the dielectric resonator is locally controlled by introducing anisotropic dielectric regions. The 3D‐printed DRA is finally measured, and its results agree well with the simulations. [ABSTRACT FROM AUTHOR]

Manufacturing thick (>10 mm) alumina (Al2O3) parts through the ceramic additive manufacturing technique of digital light processing (DLP) is difficult due to the large amount of polymer that must be removed. Nearly 35–65 vol% of a fugitive UV‐curable polymer is used in commercial ceramic slurries in order to maintain shape through the DLP process. During the thermal debind, gases form and escape quickly due to pressure build‐up, leading to defects in the form of print layer delamination. Here, we analyze the polymer decomposition through thermogravimetric analysis in order to design a less aggressive thermal debind schedule through strategic thermal holds and decreased heating rates. The new schedule led to a 83% reduction in average delaminations per sample (from 6.9 delaminations per sample to 1.2 delaminations per sample) and up to a 100% increase in wall thickness (from nominally 10–20 mm). A complex, Al2O3 turbine rotor (with maximum wall thickness of 5 mm in the center hub section) of a JetCat P400 engine was fabricated to compare the new schedule to the manufacturer provided one. The improved thermal debind schedule produced a turbine rotor with no observable delamination defects. [ABSTRACT FROM AUTHOR]

Effective thermal insulation materials rely on the fabrication of dense, ultra‐high‐temperature ceramics that can withstand harsh environments. Hafnium carbide‐based ceramics are one of the leading materials that have the potential to perform relatively well in high‐temperature oxidizing environments under mechanical loading due to their thermal and mechanical stability. In this study, we explore the effects of processing conditions to create dense, ablation‐resistant HfC–SiC composites with a fixed composition of HfC–20 wt.% SiC using a hot‐pressing method. Sintering pressure, temperature, and time were varied and the material's relative density, phase composition, morphology, microstructure, and hardness were investigated. Composite ceramics with 99% relative density relative to a theoretical value were created by hot pressing at 2100°C for 1 h at 50 MPa and displayed a fine microstructure with an average grain size of ∼5 µm and a Vickers hardness of 22.9 ±.8 GPa. The mass loss was determined using an oxyacetylene torch with cross‐section investigations of oxide surface formations and subsurface microstructural changes. These HfC–SiC samples developed a 410 nm hafnium oxide layer on the surface upon torch exposure and had an average calculated recession rate of.028 µm/s. [ABSTRACT FROM AUTHOR]

The potential of dislocations (line defects) in ceramics may have been greatly underrated until most recently. Promising proofs‐of‐concept have been demonstrated for dislocation‐tuned functional and mechanical properties, revealing a new research front for dislocations in ceramics for a wide range of potential applications. However, it is commonly known that ceramics are hard (difficult to deform) and brittle (easy to fracture), particularly at room temperature. It remains a great challenge to mechanically tailor dislocations in ceramics. To address this pressing bottleneck, this article discusses the mechanics‐based dislocation engineering in ceramics by examining the three fundamental factors of dislocation nucleation, multiplication, and motion. Successful experimental approaches to tune dislocation density and plastic zone size on single‐crystal strontium titanate are demonstrated. The dislocation‐based competition between plastic deformation and crack formation is discussed. The aspects of coupling external fields to manipulate dislocations are highlighted, which may hold the key to modulating the charged dislocation cores in ceramics and opening new routes for mechanical tailoring of dislocations at room temperature. Some open questions and challenges for engineering dislocations in ceramics are discussed. [ABSTRACT FROM AUTHOR]

Ultra-wide bandgap semiconductor Ceria oxide attracts tremendous interest because of its high stability and electrical properties. The ionic transport properties of CeO 2 have tremendously been elaborated in terms of electrolytes, especially using bulk doping like Sm doped Ceria and gadolinium doped Ceria, but challenges remain. In this work, we propose the surface doping of Sn into CeO 2 for the engineering of the electronic structure of CeO 2 with a focus on surface properties. The Sn doping into CeO 2 enables the Fermi-level to lower level, which further induces a local electric field, dramatically enhancing the surface proton transport at the surface and interface. Furthermore, higher concentrations of Oxygen vacancies and lattice disturbance on the surface layer are mainly ascribed to surface modification, which eventually promotes proton transport. The prepared fuel cell device based on Ce 0.9 Sn 0.1 O 2 as an electrolyte has delivered a total high performance of 905 mW cm−2 and proton performance of 787 mW/cm2 along with an ionic and protons conductivity of 0.21 and 0.19 S cm−1 at 520 °C. The surface doping of Sn in CeO 2 builds continuous surfaces as proton channels for high-speed transport. This work presents a reasonable methodology to develop high-performance, low-temperature ceramic fuel cells. [Display omitted] • CeSnO 2 was synthesized using the sol-gel technique. • The designed cell has a high ionic conductivity of 0.21 S/cm at 520 °C. • The proposed device has delivered a remarkable power output of 905 mW/cm2 520 °C. • Formation of BIEF due to surface doping dramatically enhances the surface's proton transport. • The DFT calculation was performed to assist the experimental results. [ABSTRACT FROM AUTHOR]

The ceramic materials of advanced thermal-barrier coatings (TBCs) must be exposed to high temperatures (over 1200°C) over a long lifespan. To meet this requirement, researchers have recently developed phase-stable ceramic materials. However, most of the newly developed materials have low fracture toughness and are easily cracked. Double-layered TBCs (DL–TBCs) can potentially provide a fast route to engineering applications of ceramic materials. The present paper attempts to extend the lifespan of DL–TBCs by matching the thickness ratio of the top layer to the bottom layer. First, the lifespans of different DL–TBCs with equivalent thermal insulation were determined in an iso-thermal cyclic test. The lifespan increased and then decreased with increasing thickness ratio. The optimized matching design of the thickness ratio (approximately 2:3) more than doubled the lifespan. Subsequently, the failure mechanism of DL–TBCs with different thickness ratios was analyzed through simulations. Varying the thickness ratio changed the lifespan by influencing the cracking driving force. Finally, to optimize the double-layer structures, the structural evolution was characterized under thermal exposure. Sintering-induced stiffening largely increased the cracking driving force, posing a main failure threat. The simulation suggested that lowering the stiffening degree in the top layer can further extend the TBC lifespan. [ABSTRACT FROM AUTHOR]

These advanced materials have a wide range of uses such as electronics, engineering ceramics and bio-ceramics. On the cover are different crystal morphologies of cerium oxide investigated for treatment of mild traumatic brain injury. B Cover Photograph b : I Articles from The International Symposium on Novel and Nano Materials 2022 (ISNNM 2022) are featured in this issue. [Extracted from the article]

Lead-free piezoceramics with superior piezoelectric properties don't meet the requirements of practical applications due to their lower phase transition temperature and poor thermal stability. In the present work, we report a new insight into the effect of glass phase on the piezoelectric, Curie temperature and thermal stability of (Ba 0.85 Ca 0.15)(Ti 0.9 Zr 0.1)O 3 (BCZT) ceramic. Unlike traditional glass materials with more than 80% of B 2 O 3 and SiO 2 as glass formers, our approach is to fabricate a glass phase (Ba 0.85 Ca 0.15)(Ti 0.9 Zr 0.1)O 3 -0.05B 2 O 3 (abbreviate BBCZT) with the same elements and concentrations as the ceramic phase. The ceramics-doped glass samples with the composition [(1-x)BCZT-xBBCZT], where x=(0.0, 0.025, 0.05, 0.075 and 0.1 wt%), were sintered according to the glass phase content. The effect of BBCZT glass composition on the crystal structure, dielectric, ferroelectric and piezoelectric properties of BCZT was investigated in detail. X-ray diffraction revealed that the addition of glass phase causes a defect engineering of the tricritical triple point of BCZT ceramic, where the tetragonal (T) and rhombohedral (R) phases were suppressed by the addition of glass phase and the T-phase has completely vanished at x = 0.05. The maximum value of permittivity (ε = 4102) and converse piezoelectric coefficient (d* 33 = 1150 Pm/V) were achieved for the 0.975BCZT-0.025BBCZT sample at ambient temperature. Furthermore, the diffusion coefficient (γ) and Curie temperature (T c) were observed to increase beyond x = 0.025, indicating enhanced thermal stability of BCZT at high glass content. These results qualify that the addition of (BBCZT) can enhance piezoelectric properties, phase transition temperature and thermal stability of BCZT ceramic which can meet wide requirements of practical applications. [ABSTRACT FROM AUTHOR]

Five kinds of 2D chiral ceramics of 3 mol% yttria-stabilized tetragonal ZrO 2 (3Y-TZP) material with an extensive relative density range was fabricated by an additive manufacturing technique based on the digital light processing (DLP) system. The in-plane compressive behaviours of the chiral structures were investigated with a uniaxial compression test. The effects of geometric parameters, including the ligament length-radius ratio and the wall thickness-radius ratio, were studied carefully through experiments. Furthermore, the relationships between Poisson's ratios and relative densities of the five chiral structures were obtained by finite element analysis. The results illustrated that increasing the relative density, like decreasing L/r or increasing t/r, is an excellent way to increase the mechanical properties of chiral ceramics, while decreasing L/r is a better way to increase the energy absorption capacity for chiral ceramics from an engineering perspective. Anti-tetrachiral ceramics own the best energy absorption capacity due to their strong deformation abilities brought by the deformation mode. The Poisson's ratio of 2D chiral structures also varies with the relative density. [ABSTRACT FROM AUTHOR]

Silicon carbide is one of the most important high-performance engineering ceramics. However, SiC ceramics with complex structure and high mechanical performance are difficult to shape, sinter, and process. Additive manufacturing is expected to solve the above problems, but the photosensitive slurry with low solid content leads to high residual Si content and low strength of final components. Here, we presented one novel strategy to prepare high-strength SiC components with complex structure by introducing quasi-spherical diamond powder as the high-density carbon source through vat photopolymerization 3D printing technology and reactive melt infiltration process. The final RB–SiC ceramics exhibited a specific flexural strength of 312.45 ± 18.75 MPa and elastic modulus of 359.16 ± 4.57 GPa, demonstrating one of the highest flexural strength and elastic modules among those reported for 3D-printed SiC composites. Owing to the high mechanical performance and simple fabrication process, this strategy has significant advantages in the manufacturing of structural SiC ceramics. [ABSTRACT FROM AUTHOR]

High speed and high efficiency machining of superalloy is a big technological challenge faced by the cutting tool industry in the world. In the present study, cutting performance of nickel-based superalloy was significantly improved by engineering the texture of SiAlON ceramic cutting tools with grains oriented parallel to the cutting edge. Orientation of the rod-like grains played a significant role in the wear resistance of SiAlON ceramic. With the rod-like grains parallel to the cutting edge of the tool, the resistance to notched wear and peeling was much higher, resulting in slow and stable flank and rake wear. The tool life of the textured tool with rod-like grains parallel to the cutting edge was 17% higher than that of the untextured tool. On the other hand, for the tools with the grains perpendicular to the rake or flank face, the friction generated during machining would be parallel to the grain direction, which led to the rapid peeling on the tool surface along the moving direction of the workpiece or the chip flow direction, resulting in rapid tool wear. The preferred orientation of mechanical properties designed by engineering grain orientation provides the possibility to optimize the cutting performance of SiAlON ceramic tool in turning superalloys. [ABSTRACT FROM AUTHOR]

Boron carbide ceramics possess high hardness, but they generally are subjected to low toughness due to strong covalent bonds. However, the fabrication of dense and pure polycrystalline boron carbide bulks with excellent mechanical properties by conventional methods remains a significant challenge. Here, the fine-grained and pure polycrystalline boron carbide bulks have been successfully fabricated utilizing submicron-sized boron carbide powder as starting materials under the condition of high pressure (5.5 GPa) and low temperature range (1000–1400 °C). The well-sintered boron carbide bulk recovered at 1000 °C exhibits a mean grain size of 205.2 ± 191.2 nm and relative density of up to ∼97%, and the measured Vickers hardness and fracture toughness achieve 35.0 ± 2.8 GPa and 4.6 ± 0.5 MPa m0.5, respectively. The outstanding trade-off between hardness and toughness demonstrated that the synergistic effect between fine grain size and dislocation, and the interplay between amorphous grain-boundary phases and pores via grain-boundary sliding have critical role in contributing to improve hardness and toughness, respectively. This study has essential implications in sintering fine-grained and pure polycrystalline engineering ceramics and superhard materials, which provide a tuning approach to enhance the mechanical properties. [ABSTRACT FROM AUTHOR]

With the progress of ceramic engineering, tough technical ceramics such as nacre-like alumina now exhibit complex fracture patterns with high degrees of deflection, branching and bridging. If these mechanisms highly contribute to improving crack resistance, the crack geometries go beyond the hypotheses assumed in standard techniques to quantify toughness, making it difficult to understand the mechanisms responsible for crack propagation. We report a robust local solution based on a combination of analytical formulas and finite element analysis to accurately estimate the effective stress intensity factors at the tips of multiple deflected cracks. The influence of sample size on local R-curves is analysed and shown to be less important relative to standard methods. We use this method to evaluate the direct influence of zirconia nanoparticles in the nacre-like structure and highlight the role of these findings in the understanding of mechanical response and future optimisation of highly textured tough ceramics. [ABSTRACT FROM AUTHOR]

The effect of MnO 2 additives on the sintering behavior and mechanical properties of alumina-toughened zirconia (ATZ, with 10 vol% alumina) composites was investigated by incorporating different amounts of MnO 2 (0, 0.5, 1.0, and 1.5 wt%) and sintering at various temperatures ranging from 1300 to 1450 °C. The addition of MnO 2 up to 1.0 wt% improved the sintered density, hardness, flexural strength, and fracture toughness of the composite. However, the addition of 1.5 wt% MnO 2 degraded the relative density, hardness, and flexural strength of the composite due to the transformation of the ZrO 2 phase from tetragonal to monoclinic and grain coarsening. Optimal results were obtained with 1.0 wt% MnO 2 and sintering at 1450 °C, which improved the mechanical properties (hardness: 13.5 GPa, flexural strength: 1.2 GPa, fracture toughness: 8.5 MPa m1/2) and lowered the sintering temperature compared to the conventional sintering temperature of ATZ composites (1550 °C). Thus, the ATZ composite doped with MnO 2 is a promising material for structural engineering ceramics owing to its improved mechanical properties and lower sintering temperature. [ABSTRACT FROM AUTHOR]

In this communication, we demonstrate a simple but powerful method to engineer dislocations into large plastic zones in various single‐crystal ceramic materials via room‐temperature scratching. By using a Brinell indenter with a diameter of 2.5 mm, we successfully produced plastic zones with a width and depth of ∼150 µm in a single scratch track, while the length of the scratch track can be arbitrarily long depending on the sample size. Increasing the number of repetitive scratching cycles increases the dislocation density up to ∼1013 m−2 without visible crack formation. The outlined experimental procedure is showcased on single‐crystal SrTiO3, MgO, ZnS, and CaF2 to demonstrate the general applicability of this technique. In light of the increasing research interest in dislocation‐tuned functional and mechanical properties in ceramics, our method will serve as a simple, fast, and robust technique to pave the road for scaling up the required large plastic zones for dislocation engineering in ceramics. [ABSTRACT FROM AUTHOR]

Power semiconductors based on silicon carbide (SiC) and gallium nitride (GaN) technologies are becoming increasingly important since they allow smaller sizes, lighter weight, lower costs, and higher efficiency of power electronics systems. Nov 8-10 Inspection Expo & Conference Austin, Texas, USA Meet industry experts, attend expert panel presentations and breakout sessions, and make connections that can boost your career and keep your inspections business on the cutting edge. Nov 5-8 LatinCorr & Intercorr 2023 Barra da Tijuca, Rio de Janeiro, Brazil In partnership with ABRACO and the AMPP Brazil Chapter, this long-awaited event will feature a comprehensive program that will help you stay ahead of industry trends and innovations in materials protection. [Extracted from the article]

Silicon nitride (Si 3 N 4) is an excellent engineering ceramic with high strength, fracture toughness, wear resistance, and good chemical and thermal stability. Recently, the enhanced thermal conductivity enables Si 3 N 4 to have potential application prospects in the electronic and orthopedic fields. Metal bonding with Si 3 N 4 is often the key to these applications. Here we report a facile approach for the titanium-activated Cu bonding on Si 3 N 4 substrates using an atmosphere plasma spray (APS) process. With X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) observation, it was shown that the interaction between the pre-bonded Ti (by APS) on Si 3 N 4 promoted the adhesion and high bonding strength of APS Cu on Si 3 N 4. The interfacial structure and phases were characterized, and tensile strength, electrical resistivity, thermal conductivity, and residual stress of Cu bonded Si 3 N 4 were measured accordingly. The APS deposited Cu layer is dense, has a high purity, and is joined firmly with Ti pre-bonded Si 3 N 4 substrate. The maximum tensile strength between Cu and Si 3 N 4 is as high as 89.4 MPa. The Si 3 N 4 substrate bonded with highly dense Cu demonstrates a low surface resistivity of 8.72 × 10−4 Ω∙mm, and high thermal conductivity of 98.12 W/m·K, which shows potential applications in electronic devices. • High tensile strength and high thermal conductivity Cu bonding silicon nitride substrate realized by the atmosphere plasma spraying. • No oxidation of Cu and Ti occurred during the APS under air atmosphere, and the surface resistivity of Cu layer is 8.72 × 10−4 Ω∙mm. • Copper circuit could be directly bonding to silicon nitride substrate with a mask. [ABSTRACT FROM AUTHOR]

A water hydraulic axial piston pump has become the preferred power component of environmentally friendly water hydraulic transmission systems, due to its advantages of a compact structure, high power density, and so on. The poor friction and wear performance in the water medium, especially under extreme conditions of high speed and high pressure, limit the engineering application of the water hydraulic axial piston pump. In this review, the research progress for key friction pair materials (such as special corrosion-resistant alloys, engineering plastics, and engineering ceramics) for water hydraulic axial piston pumps is, firstly, summarized. Secondly, inspired by nature, the processing methods, lubrication drag-reduction mechanism, and tribological properties of the biomimetic surface textures are discussed. The effects of the surface texture shape, equivalent diameter, depth, and arrangement on the pump's tribological properties are reviewed in detail. Finally, the application status of, and problems with, surface texture technology in water hydraulic axial piston pumps are summarized. It is suggested that future studies should focus on the multi-field coupling lubrication anti-friction mechanism of the multi-type composite texture under extreme conditions and mixed lubrication; and the anti-wear performance of the texture coupled with a coating modification, to further promote the surface texture in the field of lubrication antifriction engineering applications. [ABSTRACT FROM AUTHOR]

Alumina (Al 2 O 3) remains one the most important engineering ceramic for industrial applications. In addition to the α phase, transition alumina phases have interesting characteristics. Controlling the obtained phase structure from alumina melt requires processes with extreme cooling rates and therefore limits the tailoring capabilities. This study investigates how the cooling rate of pure alumina affects its microstructural properties and phase structure in plasma-based processing. The paper reports phase changes in micron sized granulated alumina particles in high-temperature plasma spheroidization and compares the results to plasma sprayed alumina coatings. Both plasma processes involve melting of the material followed by subsequent rapid cooling. Direct comparison on the alumina phase transitions is obtained for the two methodically distinct processing routes, creating unique microstructures due to difference in their cooling rates. • Alumina properties can be adjusted by controlling the cooling rate in melt quenching. • The alumina phase structure can be reprogrammed to fit a specific application. • Plasma spheroidization allows a new way to study the intermediate phases in alumina. [ABSTRACT FROM AUTHOR]

The electronic structure of the band gap determines the amount of light and its wavelength that can be absorbed by a semiconductor. Most photocatalysts are semiconductor materials, therefore, the state-of-art band gap engineering plays an important role in the efficiency of the photocatalytic reactions. Metal oxides are the most abundant semiconductors in the Earth's crust, most of which possess large band gaps. In order for oxides to be able to absorb solar energy, the band gap must be reduced. In this review, band gap of high-pressure phases of some well-known metal oxides like TiO2, ZnO, and Y2O3 are studied, which are known to be unstable at ambient pressure while having the advantage of narrow band gaps. High-pressure torsion (HPT) is introduced as an effective method for stabilization of high-pressure phases, and these phases show good activity under visible light for water splitting hydrogen or oxygen production, and/or CO2 reduction reactions. High-entropy oxides and oxynitrides are another group of materials that will be introduced for effective photocatalytic properties, synthesized by the HPT method. [ABSTRACT FROM AUTHOR]

Engineering ceramics are widely used in aerospace, 3C electronics, life sciences and other fields. However, the hard brittleness of engineering ceramics makes it difficult to process, prone to damage during processing, and difficult to balance processing efficiency and quality. In this paper, the grinding experiments of zirconia ceramics were carried out by applying precompressive stress under CA–MQL (Cold Air Minimal Quantity Lubrication, CA–MQL). The grinding force, surface morphology, subsurface damage, residual stress and roughness of zirconia ceramics under CA–MQL and traditional wet lubrication (WET) at multiple grinding depths were compared under precompressive stress of 0 MPa, 200 MPa and 400 MPa. The results show that CA–MQL significantly improves the grinding surface quality when the grinding depths are 30 μm and 50 μm compared with WET. The optimized surface roughness of 400 MPa precompressive stress combined with CA–MQL grinding reaches 17.12%. Precompressive stress significantly reduces the surface residual compressive stress by up to 32.8%. [ABSTRACT FROM AUTHOR]

Yttria-stabilized zirconia (YSZ)-based engineering ceramics are manufactured by adding non-oxide additives as the typical toughening mechanism of zirconia (ZrO 2). In this study, YSZ-10/20 vol% WC composite ceramics were prepared by pressureless sintering and hot pressing to view reaction pathways based on different driving forces. During the reactions, the decarburization of WC and the formation of ZrC were investigated at temperatures of ≥1500 °C. W was detected at 1700 °C, which is related to the thermodynamic stability of various chemical reactions in the ZrO 2 -WC binary system. The hardness of the composite ceramics decreased, whereas the fracture toughness and wear resistance increased. The phase evaluation and reaction pathways from the thermodynamic perspective derived from the YSZ-WC binary system suggest considerable potential for the future composition designs of ZrO 2 -based non-oxide composite ceramics. [ABSTRACT FROM AUTHOR]

In engineering ceramic grinding, the wheel wear states have an important influence on the processing efficiency and grinding quality. To address the difficulty of online monitoring of wheel wear states, a signal reconstruction method based on parameter-adaptive variational modal decomposition was proposed. Experiments on the entire life cycle of the grinding wheel were performed, and the wear states were classified based on the observed surface morphologies of the wheel and workpiece. Subsequently, acoustic emission signals were collected by nodes, and high correlation frequency bands were chosen and reconstructed. The signal features were extracted, and the wear states were identified based on a random forest optimization feature combination, finally. In this study, taking alumina ceramic as an example, eight groups of single-factor experiments were designed based on cumulative grinding depth to determine the optimal linear speed of the grinding wheel, worktable moving rate, and other process parameters. A total of 160 groups of AE signal samples were obtained. The results show that feature extraction by frequency bands can better reflect the changes in the grinding wheel wear states than the overall signal. In addition, optimization feature combinations based on the bands after decomposition, filtering, and reconstruction can divide and identify the various wear states more effectively. The comprehensive identification accuracy reached 90.6%. The accuracy of identifying the severe wear state reached 100%. Thus, the proposed method provides theoretical guidance for the practical industrial applications of online monitoring of wheel wear states. [ABSTRACT FROM AUTHOR]

SiC-based ceramics are of great interest for various advanced applications. However, its fabrication requires high-temperature treatment at ∼2000 – 2100 °С. In this study, we developed an approach based on low-temperature reactive spark plasma sintering to produce dense SiC-based ceramics with superior mechanical properties. It was found that an SPS temperature of 1600 °C and introduction of 10 – 15 wt% of mechanically activated non-oxide Ti–Si–C additive is required to manufacture ceramics with a theoretical density of higher than 90%. Nonetheless, employing 5 – 15 wt% of the additive mixture and an SPS temperature of 1700 °C, the maximum density of ∼ 98% was achieved. The controlled formation and decomposition of the in-situ Ti 3 SiC 2 MAX phase enables the fabrication of the engineering ceramics with enhanced compressive strength (550 MPa), elastic modulus (485 GPa), and microhardness (32 GPa), which are comparable to the best-reported SiC ceramics. The study has a significant potential for practical application in the production of advanced SiC-based ceramics for various purposes and could be used for further understanding and development of the high-temperature sintering methods. [Display omitted] • Ball mill mixing activates raw addictive powder but doesn't affect its composition. • Increasing SPS temperature to 1700 °C enhances SiC-based ceramics density. • Increasing additive content to 15 wt% enables the fabrication of dense SiC ceramics. • In situ Ti 3 SiC 2 MAX phase facilitates the formation of nanocomposite ceramic structure. • SiC ceramics with in situ Ti 3 SiC 2 additive shows superior mechanical characteristics. [ABSTRACT FROM AUTHOR]

Ceramic is an engineering material that has endeared itself to many sectors especially the building services sector where it is used for floor tiles. Machining is a necessary finishing operation after casting and other forming operations. A very important machining operation performed on ceramic materials such as tiles is grinding to pave way for easy installation, aesthetics and safety. This work investigates the elemental and chemical composition of the raw materials used in the production of the ceramic tiles under investigation and study the effect of different grinding procedures on some mechanical properties of the ceramic tiles. The tiles were ground at two different grinding speeds and two different levels (continuous and intermittent at 2 seconds intervals). Breaking strength, flexural strength, hardness, and surface roughness before and after grinding were analyzed using the Signal-to-Noise (S/N) ratio. The result revealed that the elements and their respective oxides present in the raw materials were able to give strength, rigidity and support to the ceramic article. Also, grinding was found to affect the mechanical properties of the ceramic tile samples as the breaking strength and flexural strength reduces from 339.77 N for the control sample to as low as 273.30 N and 16.40 N/mm² respectively. [ABSTRACT FROM AUTHOR]