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The effect of sintering temperature on the microstructure and electrical properties of ZnO–Bi2O3 varistor ceramics was studied in the present work. Results demonstrate that the Bi-rich phase ZnBi38O60 is generated at the ZnO grain boundaries in the prepared varistor ceramics over a range of 850–1000°C. As the sintering temperature increases, the Bi-rich insulator layer tends to widen, and the average grain size increases to 13.22 μm. The switching field, breakdown strength ( E 1 mA ), and nonlinear coefficient (α) increase, while the leakage current density ( J L ) decreases, because of an increase in barrier height ( φ B ). In addition, the sintering temperature promotes a decrease in the dielectric constant ( ε a ) and an increase in dielectric loss. The ZnO–Bi2O3 varistor ceramic sintered at 1000°C exhibits excellent overall electrical properties, with a switching field of 228.04 V/mm, E 1 mA of 379.76 V/mm, α of 6.02, J L of 140 μA/cm2, φ B of 0.39 eV, and ε a of 172.87 at 1 kHz. [ABSTRACT FROM AUTHOR]

To prepare bio-scaffolds with multi-stage pores, excellent mechanical and biological properties to meet the requirements of personalized bone repair, digital light processing using Pickering emulsion as paste has been proposed here firstly for porous hydroxyapatite scaffolds with complex shape and fine microstructure. It is found that dispersant content, solid loading and oil to water ratio of Pickering emulsions play vital roles on the controlling of pore morphology and pore size distribution of final hydroxyapatite ceramic foams. The multi-stage pores consist of millimeter-scale pores designed by 3D models and micro-pores below 10 µm derived from emulsion droplets. Due to the integration of hierarchical pores at different scale levels and micropores, hydroxyapatite ceramic foams possess outstanding compressive strength of 4.46–8.03 MPa at porosity of 76.59-72.96%. In vitro cell experiments illustrate that rat bone mesenchymal stem cells can spread and adhere to bio-scaffolds, promoting cell proliferation effectively and further verifying their good biocompatibility. [ABSTRACT FROM AUTHOR]

This study delves into the microwave dielectric properties of Li2Y9(SiO4)6O2F ceramics, synthesized using the conventional solid-state method. By employing x-ray diffraction analysis and meticulous data refinement across various temperatures, we unequivocally confirm the hexagonal crystal structure of Li2Y9(SiO4)6O2F ceramics. The refined lattice parameters, observed at a sintering temperature of 1275°C, exhibit a = b = 9.33318 Å, c = 6.71725 Å, with a corresponding unit cell volume of V = 506.73529 Å3. In-depth scrutiny of the microstructure of the ceramics' grains using scanning electron microscopy (SEM) reveals an optimal relative density of 96.2%. Subsequently, the study explores the impact of porosity, packing fraction, relative density, and Si-O bond valence (VSi-O) on the microwave dielectric properties of Li2Y9(SiO4)6O2F ceramics. Notably, the Li2Y9(SiO4)6O2F ceramic sintered at 1275°C demonstrates superior performance metrics, boasting an εr value of 14.28, a Q × f product of 16,760 GHz (at f = 9.4 GHz), and a temperature coefficient of frequency (τf) at 3.14 ppm/°C. This comprehensive investigation contributes valuable insights into optimizing the microwave dielectric characteristics of Li2Y9(SiO4)6O2F ceramics for potential applications in advanced electronic devices. [ABSTRACT FROM AUTHOR]

In this work, a silicate ceramic, CaY2Al4SiO12 (CYASO), with a low dielectric constant and low loss was prepared using traditional solid-state methods. X-ray diffraction (XRD) refinement analysis shows that the CYASO material crystallized into a phase with an Ia-3d space group and an impurity peak. The orthogonal cubic structure of the CYASO ceramic was confirmed through transmission electron microscopy (TEM), and the structure exhibited an orderly layered arrangement. The internal microstructure was characterized using scanning electron microscopy (SEM), which showed that the sample's relative density reached 97.8%. We discuss the correlation between the full width at half maximum (FWHM) of the Raman matrix corresponding to the vibration mode of the symmetric bending mode of AlO4 at the Raman shift of 855 cm−1 and the Q × f value. Additionally, the analysis focused on the various factors that influence the dielectric constant, including density, secondary phase, and porosity changes. The ceramics exhibited remarkable microwave dielectric properties (εr = 8.7, Q × f = 34,700 GHz, τf = −35 ppm/°C) when calcined at 1425°C. CYASO ceramic shows great capacity as a microwave dielectric material. [ABSTRACT FROM AUTHOR]

Powder‐based piezo‐catalysis, as an effective approach to degrade wastewater and produce hydrogen from water splitting, has been widely used in the field of energy conservation and pollution reduction. However, these hard‐to‐recycle powders pose a challenge of secondary pollution in the environment. As a result, this paper provides an alternative strategy based on the manufacture of porous ceramics as a green chemistry approach to replace ferroelectric powders currently used in traditional piezo‐catalysis. The piezo‐catalytic properties of Ba0.75Sr0.25TiO3 (BST) ceramics prepared using freeze casting and direct ink writing techniques are investigated in detail. The positive effect of introducing micro‐ and macro‐pores is explored and discovered, where a BST ceramic with hierarchical pore channels is prepared by a combination of direct ink writing and freeze casting and exhibts the highest first‐order kinetic rate constant per mass of catalysts, k, of up to 2.91 min−1 kg−1 compared to bulk BST ceramics. This study therefore provides the first report for the benefits of hierarchical porous ferroelectric ceramics used in water splitting, with an average H2 production rate reaching 848.88 nmol g−1 h−1. [ABSTRACT FROM AUTHOR]

Bi‐Zn‐Nb‐O‐based microwave dielectric ceramics are promising candidates for wireless communication. Investigations have concentrated on their fabrication methods and doping modification. In this work, the densification mechanism and grain growth kinetics of the Bi‐Zn‐Nb‐O‐based microwave dielectric ceramics were explored. A significantly wide sintering temperature window (800–1000°C) of the monoclinic Bi2Zn2/3Nb4/3O7 (BZN) was found. High‐density stacking faults were observed in BZN grains at the initial stage of sintering, which could act as paths for mass transport, thus remarkably accelerating the densification process and decreasing the densification temperature. On the other hand, BZN possesses a high grain growth exponent and activation energy, which indicates a slow grain growth rate and a high threshold for abnormal grain growth, corresponding to the wide sintering temperature window. Moreover, the BZN ceramics display good microwave dielectric properties stability over a wide temperature range (25–450°C). [ABSTRACT FROM AUTHOR]

As a wide band gap semiconductor, alkaline-earth metal sulfides (AES) with low phonon energy, high laser damage threshold, and high transmittance in infrared, have wide application prospects in bioimaging, spectral conversion, and solid-state lighting. However, AES nanocrystals (NCs) suffer from the weak chemical-stability and low mechanical-stability, and can be easily oxidized in humidity and oxygen. Incorporation of AES NCs into inorganic glass is expected to overcome those inherent limitations. In this work, a new type of oxysulfide glass-ceramics containing CaS, SrS, BaS, Sr x Ba 1−x S, and Ca x Sr 1−x S NCs is developed, and average diameters of these AES NCs are tuned in the range of 3–18 nm. Precipitation of AES NCs not only improves the mechanical properties of glass, but also maintains high transmittance (˃60%) in the spectral range of 1–4.3 µm. Results reported in this work offer a new pathway for developing novel oxysulfide glass-ceramics for multi-functional optical devices. [ABSTRACT FROM AUTHOR]

In order to improve the filtration performance, silicon carbide porous ceramics with network cell wall were fabricated via the polyurethane foaming method using silicon carbide powder, alumina powder, polyether polyol, polymethylene polyphenyl polyisocyanate, dibutyltin dilaurate, triethylenediamine and silicone oil (foam stabilizer) as raw materials. The effects of the solid loadings of the slurry (45%, 50%, 55% and 60%, by mass) on the microstructure, physical properties and their filtration properties towards particu-late matters were studied. The result shows that: (1) with the increasing solid loading, the bulk density and cold compressive strength gradually increase, and the apparent porosity decreases; (2) the micropores generated during the polyurethane foaming process are distributed on the ceramic pore wall to form a network cell wall structure, which increases the collision probability between particles and the wall pores and improves the filtration efficiency; meanwhile, the network cell wall structure also improves the pore interconnectivity and reduces the press drop; (3) when the solid loading is 55%, the silicon carbide based porous ceramics have the bulk density of 0.57 g · cm-3, apparent porosity of 79.2%, cold compressive strength of 3.7 MPa, and the filtering efficiency of the paniculate matter of 91.2%, achieving good regeneration performance. [ABSTRACT FROM AUTHOR]

The oxidation behavior of SiC ceramics is vital to assess its lifetime under extreme conditions within nuclear power systems. Employing systematic first-principles calculations, we studied the oxygen (O) properties in 3C-SiC without and with irradiation-induced defects to understand the oxidation mechanism. Interstitial O (O i n t) exhibits two energetically favored states with an energy difference of only 0.02 eV. Two O i n t atoms have a strong mutual attraction, with a binding energy reaching 0.80 eV. The stability of O-related defects with charge was investigated. The formation energy of O at the carbon site (O C) is negative, implying that the dissolution of O in the host carbon site is exothermic. The binding strengths of O i n t and O C with irradiation-induced defects are notably high. The formation energies of O and carbon vacancy clusters (V C m O n) decrease approximately linearly and turn negative as the number of O increases. The binding energy of V C m O n is still very high, indicating a strong attraction between them. Furthermore, Trapping of O by carbon vacancies may reduce the mobility of O. Electronic properties are analyzed to reveal the interaction mechanism between irradiation-induced defects and O. The irradiation-induced defects may enhance the oxidation of SiC due to the strong binding energies. [ABSTRACT FROM AUTHOR]

Reticulated porous MgO ceramics were fabricated by suspension impregnation method, which involves replication of polyurethane foam with mixed slurry of MgO and MgF2 and subsequent sintering treatments. The objective of the present study is to find a suitable method to ensure uniform macropore or micropore structure of ceramics foam using low-melting additives at moderate sintering temperatures. The microstructures of Magnesia Foam Ceramics (MFC) were evaluated by scanning electron microscopy (SEM) coupled with X-ray diffraction (XRD). The loading amount and apparent porosity of MFC are related to the slurry viscosity and PPI of PU foam. More importantly, compared with different filtration methods of molten crude magnesium, we can draw a conclusion that MFC can clean MgO inclusions and refining agent effectively based on the test results of electron dispersive spectroscopy (EDS) and density of crude magnesium before and after filtration.These results are attributed to the formation of filter sieve removing particles larger than or close to the pore size and to liquid inclusions held to the filter wall by surface forces, owing to specific surface area resulted by macropores and micropores formed in MFC in the presence of polyurethane foam and sintering binder MgF2 powders. [ABSTRACT FROM AUTHOR]

The pure Ag 2 SrV 4 O 12 powder with tetragonal structure was directly synthesized via high-energy milling. The dense Ag 2 SrV 4 O 12 ceramics, sintered at as low temperature as 420 °C, have a low relative permittivity (ε r) of 6.39, a high quality factor (Q × f) of 51,584 GHz (f = 13.66 GHz), and a temperature coefficient of resonance frequency (τ f) of −79.8 ppm/°C. For practical applications, a composite with balanced microwave dielectric properties (ε r = 11.86, Q × f = 38,061 GHz, τ f = −8.2 ppm/°C) was realized at 460 °C by adding TiO 2 with positive τ f to Ag 2 SrV 4 O 12 ceramics. There was no chemical reaction between Ag 2 SrV 4 O 12 ceramic and Ag/Al, which shows the good chemical compatibility of Ag 2 SrV 4 O 12 and Ag/Al. All results indicate that Ag 2 SrV 4 O 12 has a promising future as an ultra-low temperature co-fired ceramic. [ABSTRACT FROM AUTHOR]

The structural characteristics and microwave dielectric properties of SrBi2TeO7 ceramics intended for low-temperature co-fired ceramic (LTCC) applications were investigated. Comprehensive analyses were conducted using x-ray diffraction, structural refinement, transmission electron microscopy, Raman spectroscopy, and x-ray photoelectron spectroscopy. The findings demonstrated that SrBi2TeO7 ceramics possess a pure cubic structure. Scanning electron microscopy characterizes the grain microstructure, revealing a relative density of 95.5% for SrBi2TeO7 ceramic. Optimal microwave dielectric properties were achieved for SrBi2TeO7 ceramics calcined at 765°C, displaying a relative permittivity (εr) of 24.96, a Q × f value of 25,898 GHz (f = 6.6 GHz), and a temperature coefficient of resonant frequency (τf) of –80.7 ppm/°C. The combination of low sintering temperature and minimal dielectric loss renders these ceramics advantageous for utilization in LTCC materials. [ABSTRACT FROM AUTHOR]

This study presents the dielectric properties of Ba2Zr2Si3O12 ceramics, synthesized using the solid state method. The cubic crystal structure of Ba2Zr2Si3O12 ceramics was conclusively verified through the analysis of XRD patterns and subsequent structural refinement. Refined lattice parameters of a = b = c = 10.23178 Å were found, with a corresponding unit cell volume of V = 1071.159026 Å3. The grain microstructure of the ceramics was characterized using SEM, which showed density of 97.6% for the Ba2Zr2Si3O12 ceramic. The Si-O bond valences (VSi-O) were found to be closely related to the τf of the Ba2Zr2Si3O12 ceramics. The microwave dielectric properties of the Ba2Zr2Si3O12 ceramics sintered at 1490°C were ascertained to be εr = 15.08, Q × f = 14885 GHz (f = 9.9 GHz), and τf = −78.6 ppm/°C. [ABSTRACT FROM AUTHOR]

Novel ultra-low-loss Li 3 Mg 3 NbO 7 ceramics were synthesized using solid-state reaction method. The microstructure, bond characteristics, and microwave dielectric properties (MDPs) of the Li 3 Mg 3 NbO 7 ceramics were explored. Furthermore, the Li 3 Mg 3 NbO 7 ceramics crystallized in the orthorhombic rock-salt structure and the optimized density (97.7%) was obtained at 1200 °C. Utilizing complex chemical bond theory (P–V-L theory) and Raman spectra, the connection between structure and properties was constructed. ε r value was mainly affected by the ρ rel and average ionic polarization. The U Nb – O and packing fraction were the key internal factors influencing the Q × f value. The τ f was intimately relevant to Nb–O bond and τ ε. Notably, the Li 3 Mg 3 NbO 7 ceramics sintered at 1200 °C exhibited excellent MDPs (ε r = 14.7, Q × f = 121,047 GHz, τ f = −24.8 ppm/°C), offering enormous prospects for 5G/6G communication applications. [ABSTRACT FROM AUTHOR]

Reactive sintering has been widely utilized to densify ceramics. Although the technology has numerous advantages, the composition of as-sintered ceramics is hard to be adjusted unless additional products are added. In this work, a novel solid-state route based on the reactions among TiN, Al and B were proposed to consolidate TiB 2 -AlN- h BN ceramics (TAB) with tunable compositions (h BN ≤ 42 vol%, AlN ≤ 45 vol%). Dense TAB with high relative density, refined grain size and homogeneous microstructure were obtained via spark plasma sintering at 1800 °C and 60 MPa. It was found that exothermic reactions between the reactants could be ignited during heating, and the order of temperature at which the combustion process occurred was just opposite to the sequence of adiabatic temperature for individual reactions. Effects of h BN and AlN amounts on the densification, microstructure, mechanical properties, machinability and electrical resistivity of as-sintered ceramics were comprehensively investigated. Compared to AlN, h BN content played a more obvious role on those properties. As h BN contents increased from 0 to 42 vol%, the flexural strength, fracture toughness, Vickers hardness and modulus of TAB continuously decreased. TAB with h BN amounts ≥ 13 vol% exhibited better machinability with surface roughness lower than 2.9 µm after machining. Nevertheless, their electrical resistivity values at room temperature fluctuated in a narrow range between 43 μΩ·cm and 83 μΩ·cm, irrelevant with the h BN amounts. • TiB 2 -AlN- h BN ceramics with tunable compositions were reactively densified without adding external h BN or AlN at reduced temperature. • Relationships between the adiabatic temperature and the temperature when reactions occurred in the TiN-Al-B system were investigated. • TiB 2 -AlN- h BN ceramics with synergistically improved mechanical, electrical and machinability were achieved. [ABSTRACT FROM AUTHOR]

Designing high-performance ceramic adsorbent with a wide spectrum of properties such as regulatable pore structure, high surface area, ultrahigh organic dye removal efficiency and renewability in an affordable and rational approach is vital for real-life applications. However, integrating all these individual functionalities simultaneously into one bulky material is still challenging. Herein, hierarchical porous ceramic adsorbents with nanofibrous-granular composite structure were proposed via colloidal co-assembly of coal-containing kaolin waste and silicon to resolve the above conflicting demands. Such structure endows the resultant products with satisfactory surface area of 52 m2 g−1, ultrahigh malachite green removal efficiency of 97.6%, outstanding adsorption capacity of 97.6 mg/g, excellent renewability after calcining at 500 °C. Such ceramic adsorbent provides a sustainable and feasible strategy for fabricating water purification materials. [ABSTRACT FROM AUTHOR]

The spinel and pseudobrookite type ceramic materials have been widely used in different industries including ceramics, refractory and metallurgy. Therefore, their physicochemical properties are important for the development of related processes. In this regard, it is important to understand the formation principles of the spinel and pseudobrookite solid solutions. In the present work, the equilibrium phase relations for the MgO-Al2O3-TiO2 system at 1700°C in air were experimentally determined by high-temperature equilibration-quenching technique followed by XRD and SEM–EDS analyses. The pseudobrookite solid solution was found to be coexisting with spinel solid solution and rutile phase, respectively. The composition evolution and formation principles of the pseudobrookite and spinel solid solutions were further elucidated from the corresponding crystal structures and composition relations. Furthermore, great discrepancies were observed when the 1700°C isotherm from the present work was compared with the isotherm simulated by FactSage 8.1. The evolution of the solid solution existing area was intuitively presented with reference to the experimental data from the literature. The results from present work are important for the development of spinel and pseudobrookite solid solution ceramics as well as the optimization of the thermodynamic database for oxide systems. [ABSTRACT FROM AUTHOR]

Ti4+-ion-doped (n + 1)SrO − nCeO2 (n = 2) ceramic systems were prepared with the conventional solid-state reaction method, and the effects of the phase structures and compositions, sintering behaviors, microstructures and microwave dielectric properties of these ceramic systems were investigated in detail as a function of TiO2 content. The analytical results of the XRD patterns show that the pure (n + 1)SrO − nCeO2 (n = 2) system is a composite-phase ceramic system with coexisting SrCeO3 and Sr2CeO4 phases (represented as a SrCeO3 + Sr2CeO4 system), which belong to the orthogonal structures of the Pmcn (62) and Pbam (55) space groups, respectively. For the xTiO2-(1 − x) (SrCeO3 + Sr2CeO4) (x = 0.1–0.4) ceramic samples, the secondary phase Sr2TiO4 can also be detected within the range of the investigated components. Meanwhile, the Raman spectroscopy, SEM-EDS, and HRTEM (SAED) analysis results also verified the correctness and consistency of the phase structures and compositions for all the given specimens. In addition, complex impedance spectroscopy was used to detect the conductive behavior of these compound ceramic systems, and the calculation results show that the appropriate addition of Ti4+-ions can make the SrCeO3 + Sr2CeO4 system have better thermal stability. The composition of x = 0.2 multiphase structural ceramic sample sintered at 1330 °C for 4 h has a near zero τf value of ~−4.6 ppm/°C, a moderate εr of ~40.3 and a higher Q × f~44,020 GHz (at 6.56 GHz). The relatively superior-performing ceramics developed in this work are expected to provide a promising microwave dielectric material for communication components. [ABSTRACT FROM AUTHOR]

The development of high-performance solid-state electrolyte (SSE) films is critical to the practical application of all-solid-state Li metal batteries (ASSLMBs). However, developing high-performance free-standing electrolyte films remains a challenging task. In this work, we demonstrate a novel scalable solvent-free process for fabricating high ceramic content composite solid-state electrolyte (HCCSE) films. Specifically speaking, a mixture of ceramic and polymer is dry mixed, fibered, and calendered into a free-standing porous ceramic film, on which polymer precursor is coated and polymerized to bridge the inorganic ceramic particles, resulting in a flexible HCCSE film with a ceramic content of up to 80 wt.%. High ceramic content not only leads to high ionic conductivity but also brings good mechanical properties; while the organic phase enables electrode electrolyte interfacial stability. When Li10GeP2S12 (LGPS) and polymeric ionic liquid-based solid polymer electrolytes (PIL-SPEs) were used as the inorganic and organic phases, respectively, the room temperature ionic conductivity of the resulted HCCSE reaches 0.91 mS·cm−1. Based on this HCCSE, Li∥Li symmetric battery cycled stably for more than 2,400 h with ultra-low overpotential, and ASSLMBs with different cathodes (LiFePO4 and sulfurized polyacrylonitrile (PAN-S)) present small polarization and decent cyclability at room temperature. This work provides a novel scalable solvent-free strategy for preparing high-performance freestanding composite solid-state electrolyte (CSE) film for room temperature ASSLMBs. [ABSTRACT FROM AUTHOR]

Inkjet printing technology can make tiles with very rich and realistic patterns, so it is widely adopted in the ceramic industry. However, the frequent nozzle blockage and inconsistent inkjet volume by inkjet printing devices, usually leads to defects such as stayguy and color blocks in the tile surface. Especially, the stayguy in complex pattern is difficult to identify by naked eyes due to it is easily covered by complex patterns and becomes invisible, this brings great challenge to tile quality inspection. Nowadays, the machine learning is employed to address the issues. The existing machine learning methods based on hand‐crafted features are capable of stayguy detection of the tiles with a simple pattern, but not applicable for complex patterns due to the interference of pattern in feature extraction. The emerging deep‐learning‐based methods have the potential to be applied for stayguy detection with complex patterns, but cannot achieve real‐time detection due to high complexity. In this paper, a lightweight hand‐crafted feature enhanced convolutional neural network (named HFENet) is proposed for rapid defect detection of tile surface. First, we perform data enhancement on the original image by global histogram equalization and image addition. Second, for the special shape of stayguy which is usually vertical, we embed the extended vertical edge detection operator (Prewitt) as convolution kernel into HFENet to extract the hand‐crafted vertical edge features of the test image and eliminate the interference of complex pattern in the feature extraction. Third, the 5 × 1 asymmetric convolution kernel with a dilation rate of 2 is used to improve the utilization of convolution kernel and reduce the complexity of the model. Fourth, to reach the real‐time requirements, a memory access cost‐aware design is proposed, which can orchestrate the number of shallow convolution layers and deep convolution layers in feature extraction. The experiments were performed on the ceramic tile image data set captured by high‐resolution industrial cameras in ceramic tile production line. Experimental results show that the HFENet outperforms the state‐of‐the‐art semantic segmentation networks (i.e., UNet, FCN‐8s, SegNet, DeepLabV3+, etc.) and lightweight networks (i.e., ShuffleNet, MobileNet, and SqueezeNet). All the code and data are available at a GitHub repository (https://github.com/RobotvisionLab/HFENet). [ABSTRACT FROM AUTHOR]

Ceramic foams constructed by aqueous-based foam templating have demonstrated great potential in industrial and research applications. However, a multiple-phased suspension with inherently improved complexity inevitably leads to a severe deterioration of foam stability. Herein, we proposed a colloidal co-assembly strategy that introduces Al–Al2O3 dual-phased particles for constructing ultralight yet mechanically robust cellular ceramics. Owing to the Al2O3 oxidation layer on Al particles, both of Al and Al2O3 suspensions demonstrated similar zeta potential and rheological properties, enabling a stable foam structure after colloidal co-assembly. High-temperature oxidation of Al particles contributed to the reinforcement of cell wall and formation of Al2O3 whiskers. The calcined products demonstrated a lightweight structure (0.31 g cm−3), a robust compressive strength (3.64 MPa) at a porosity level of 88.5%, and a relatively high specific surface area (14.7 m2 g−1 ). The current strategy paves the way for the construction of high-performance ceramic foams for a broad range of applications. [ABSTRACT FROM AUTHOR]

Summary: With the rapid development of electronic industry, the miniaturization and integration of components have become an irreversible development trend, which puts forward high requirements for lead‐free ceramic materials with excellent recoverable energy storage density and efficiency. In addition, it is also a great challenge to sustain excellent energy storage performance under different environmental conditions. In this work, a combined design strategy was proposed to induce polar nano regions and reduce grain size by introducing SrTi0.5Zr0.5O3 (STZ). The addition of STZ reduced the grain size to submicron level, accompanied by relaxation enhancement. The high energy storage properties (Wrec = 1.85 J/cm3, η = 65.92%) were achieved in 0.80Bi0.5Na0.5TiO3‐0.20SrTi0.5Zr0.5O3 (BNT‐STZ) ceramics at 150 kV/cm. Excellent temperature stability (40°C‐160°C) and frequency stability (1‐500 Hz) of energy storage performance have been obtained under 100 kV/cm, with the fluctuations below 8%. Importantly, A high power density of 3.64 MW/cm3 and a transitory discharge time (t0.9 ~ 0.632 μs) were achieved for 0.80BNT‐0.20STZ ceramic under 160 kV/cm. These characteristics indicate that 0.80BNT‐0.20STZ ceramic is expected to be applied in high‐power equipment. Highlights: A combined design strategy was proposed to induce polar nano regions and reduce grain size by introducing STZ.0.80BNT‐0.20STZ ceramic possesses a recoverable energy density of 1.85 J/cm3 and efficiency of 65.92%.0.80BNT‐0.20STZ ceramic exhibits good electrical stability in wide frequency (1‐500 Hz) and temperature range (40‐160°C).A high power density (PD) of 3.64 MW/cm3 and a transitory discharge time (t0.9 ~ 0.632 μs) can be achieved. [ABSTRACT FROM AUTHOR]

In this work, the efficacy of sintering aid BaO–ZnO–Li2O–B2O3–SiO2 (BZLBS) on the sintering process at lower temperatures was verified for the Ca0.244Li0.3Nd0.404Ti0.96Al0.02Nb0.02O3 (CLNTAN) ceramics. Crystalline phases and dielectric properties of samples were systematically investigated as well. The results exhibited that the BZLBS apparently reduced the sintering temperature of CLNTAN by forming the liquid phase. Additionally, doping BALBS sintering aid not only reduced the sintering temperature, but also declined the dielectric constant (εr) and the quality factor (Q × f) for CLNTAN ceramic. Eventually, the microwave dielectric properties are as follows: εr = 104.7, Q × f = 2560 GHz and τf = − 2.1 ppm/°C (sintered at 950 °C). The results demonstrated that the CLNTAN ceramic doped with 4 wt% BZLBS is a potential LTCC ceramic application. [ABSTRACT FROM AUTHOR]

• (1-x)ZnO + xNa 2 CO 3 (x = 0, 0.5, 1.0, 1.5 mol%) varistor ceramics were fabricated via the solid-state sintering technique at a low sintering temperature of 900 ℃. • The Na 2 CO 3 additive markedly reduced the donor density and interface state density. However, it increased the barrier height, thereby enhancing the switching field, breakdown strength, and the nonlinear coefficient. • The dielectric constant of varistor ceramic decreased with increasing Na 2 CO 3 concentrations because that the dielectric constant is proportional to the ratio of the average grain size to the depletion layer width. Herein, (1-x)ZnO + xNa 2 CO 3 (x = 0, 0.5, 1.0, and 1.5 mol%) varistor ceramics were prepared via conventional solid-state sintering at a low sintering temperature of 900 ℃. The microstructure and electrical properties of these varistor ceramics were systematically investigated as a function of Na 2 CO 3 concentration. Results revealed that the prepared varistor ceramics exhibit the hexagonal structure without a secondary phase. The increase of Na 2 CO 3 concentration promotes the ZnO grain growth. Owing to an increasement in the barrier height at the grain boundaries, the nonlinear electrical properties of the ceramics considerably improve with increasing Na 2 CO 3 concentration. The optimal composition of 98.5 mol%ZnO + 1.5 mol%Na 2 CO 3 corresponds to a nonlinear coefficient of 3.55, leakage current density of 450 μA/cm2, breakdown strength of 241.2 V/mm, and barrier height of 0.57 eV. Moreover, the dielectric properties of the varistor ceramics are considerably affected by Na 2 CO 3 concentration. [ABSTRACT FROM AUTHOR]

Gas-in-liquid foam templating is considered as a promising method for commercial-scale production of porous materials. However, Ostwald ripening occurs frequently during the preparation, which could bring about inhomogeneous bubbles with large sizes and deteriorate the performance of resultant products. To tackle this challenging task, we report a gelation network-triggered morphology-regulation strategy during the foaming process. As an exemplar, boehmite sol was incorporated into the andalusite suspension to stabilize the foam framework. After casting, the wet foam was able to maintain its overall shape, since andalusite particles were anchored onto the gas-liquid interface by the gelation network during mechanical frothing. The samples calcined at 1400°C feature homogeneous bubble with hierarchical porous architecture, smaller pore size with a mean value of 5.32 μm and robust compressive strength of 11.97MPa at a porosity level of 84 %. Our approach substantially broadens the design philosophy of high performance porous ceramics. [ABSTRACT FROM AUTHOR]

• ZrB2-SiC ceramics were joined using Ni foil filler and spark plasma sintering. • Joining mechanisms of ZrB2-SiC ceramics were identified. • Mechanical tests were performed to evaluate the mechanical properties of the fabricated joints. • Oxidation behaviour of the joint was characterised and analysed over a wide range of temperature. Joining is crucial for ultra-high temperature ceramics (UHTCs) to be used in demanding environments due to the difficulty in manufacturing large and complex ceramic components. In this study, ZrB 2 -SiC composite UHTCs parts were joined via Ni foil as filler, and the mechanical properties and oxidation behaviour of the fabricated ZrB 2 -SiC/Ni/ZrB 2 -SiC (ZS/Ni/ZS) joint were investigated. Firstly, dense ZrB 2 -SiC composites were prepared from nano-sized powders by spark plasma sintering (SPS). The ZrB 2 -SiC parts were then joined using SPS. Furthermore, the elastic modulus, hardness, shear strength and high temperature oxidation behaviour of the ZS/Ni/ZS joint were examined to evaluate its properties and performance. The experimental results showed that the ZrB 2 -SiC parts were effectively joined via Ni foil using SPS and the resultant microstructures were free from any marked defects or residual metallic layers in the joint. Although the elastic modulus and hardness in the joining zone were lower than those in the base ZrB 2 -SiC ceramics, the shear strength of the joint reached ∼161 MPa, demonstrating satisfactory mechanical properties. Oxidation tests revealed that the ZS/Ni/ZS joint possesses good oxidation resistance for a wide range of elevated temperatures (800–1600 oC), paving the way for its employment in extreme environments. [ABSTRACT FROM AUTHOR]

In this paper, 3D-SiC network skeleton with different structures was successfully constructed by regulating the microstructure of SiC foam ceramic struts via polyurethane replication technology combined with reactive infiltration of Si and solid-state sintering. Then, SiC/Al composites with 3D-interpenetrated network structure (3D-SiC/Al) were fabricated via vacuum pressure infiltration of Al alloy into the 3D-SiC skeleton, for application as electronic packaging. The effects of different skeleton structures on the thermal conductivity (TC), coefficient of thermal expansion (CTE), and flexural strength of the composites were investigated in detail. Furthermore, representative volume element (RVE) models of the 3D-SiC/Al composites were developed and their heat transfer properties and dimensional stability were also comparatively analyzed by finite element (FE) simulations. The results showed that the 3D-SiC/Al composites exhibited high TC of 196 W/m·K, low CTE of 8.03 × 10−6 K−1, and excellent flexural strength of 272 MPa. Low thermal deformation parameter (TDP) and Ashby map demonstrated that the synergistic effect of a complete 3D network skeleton and a clean well-bonded interface in the 3D-SiC/Al composites facilitated the integration of low CTE and high TC even at a low SiC content of 30 vol%. The FE results revealed a 63.5 % reduction in thermal stress and nearly an order of magnitude increase in heat flux for the RVE model of 3D-SiC (30 vol%)/Al composite compared to the RVE model of SiC P (60 vol%)/Al composite. This work provides a novel and scalable method for designing and synthesizing various composites for electronic packaging. [ABSTRACT FROM AUTHOR]

Li 3 Mg 4 NbO 8 -basic composite ceramics were elaborated via the solid-state reaction process, in which LiF and Ba 3 (VO 4) 2 were utilized as a sintering aid and reinforcement phase, respectively. The sinterability, phase assemblage, microstructures, and microwave dielectric performances of Li 3 Mg 4 NbO 8 –LiF–Ba 3 (VO 4) 2 composite ceramics were thoroughly researched. The co-addition of LiF–Ba 3 (VO 4) 2 can simultaneously lower the sintering temperature and improve the thermal stability of Li 3 Mg 4 NbO 8 -basic ceramics. Solid state activated sintering is responsible for the low-temperature densification of the present ceramics. The coexistence of rock-salt structural Li 3 Mg 4 NbO 8 /Li 4 Mg 4 NbO 8 F and hexagonal structural Ba 3 (VO 4) 2 phases was demonstrated by the combinational XRD and SEM-EDS analysis results. The 0.65(Li 3 Mg 4 NbO 8 –LiF)-0.35Ba 3 (VO 4) 2 ceramics fired at 825 °C/5 h exhibited promising microwave dielectric performances: τ f = 0.5 ppm/°C along with ε r = 13.8 and Qxf = 68500 GHz. The good compatibility of the developed ceramics with Ag demonstrates it potential for use in LTCC technology. [ABSTRACT FROM AUTHOR]

In this study, novel lead-free (1- x)Sr 0·7 Bi 0·2 TiO 3 - x La(Mg 0·5 Zr 0.5)O 3 ((1- x)SBT- x LMZ) ceramics were designed and fabricated by the conventional solid-state reaction method. The dielectric performance, energy storage characteristics and charge-discharge behavior of the ceramics were systematically investigated. Specifically, the temperature stability of dielectric constant is improved by doping SBT with LMZ. On a separate note, BDS is also enhanced ascribed to the reduction of the grain size. Consequently, the 0.87SBT-0.13LMZ exhibits high critical electric field of 340 kV/cm with ultrahigh efficiency (η) of 98.2% and recoverable energy storage density (W rec) of 1.22 J/cm3. Moreover, pulsed charge-discharge test elucidates that 0.87SBT-0.13LMZ possesses great thermal stability (30 °C–150 °C) along with a fast discharge period of 0.125 μs, high power density (P D) of 72.38 MW/cm3 as well as a high pulsed discharge energy density (1.2 J/cm3) at 380 kV/cm. Based on these outstanding characteristics, the 0.87SBT-0.13LMZ is considered as a potential candidate for pulse systems. [ABSTRACT FROM AUTHOR]

yBa1−xSrxCuSi2O6-(1−y) Ba0.55Sr0.45TiO3 (x = 0, 0.2 and y = 10 wt%, 30 wt%) ferroelectric-dielectric composite ceramics were prepared by the solid-state sintering method. The relationship among phase composition, microstructures and dielectric properties has been investigated. By adjusting the content of the Ba1−xSrxCuSi2O6 and the content of Sr2+ in the Ba1−xSrxCuSi2O6, the effect of the dielectric material on BST was studied. With the increase of Ba1−xSrxCuSi2O6 content and the increase of the Sr2+ content, the dielectric peak of the composite material is gradually suppressed and broadened, and the Curie temperature (Tc) moves to the low temperature. The introduction of Ba1−xSrxCuSi2O6 reduced the permittivity of the composite material to a certain extent, at the same time, the dielectric tunability and quality factor (Q) value are maintained at a high level. The dielectric tunability of the four composite ceramics obtained is still higher than 10% under the applied electric field (at 30 kV/cm). The 30 wt% BCSO–70 wt% BST55 system and the 30 wt% BSCSO–70 wt% BST55 system has lower dielectric permittivity (830, 577), higher dielectric tunability (17.3%, 10.2% at 30 kV/cm) and a decent Q value (149 at 1.25 GHz, 168 at 1.31 GHz). [ABSTRACT FROM AUTHOR]

Compared to samples sintered from directly mixed powders, reactive sintering enables the production of denser ceramic materials with finer grains at even lower temperatures. However, there is a lack of quantitative comparisons between the two sintering approaches in terms of densification mechanisms and grain growth kinetics. In this work, taking two types of TiB 2 -SiC- h BN ceramics sintered from raw powders containing TiB 2 , SiC and h BN (TSB-M) and TiN, Si and B 4 C (TSB-R) as model materials, above mechanisms were quantitatively investigated using spark plasma sintering. Effects of dwell temperature and sintering pressure on the microstructure evolutions, densification kinetics as well as grain growth of TSB-R and TSB-M were thoroughly examined. The densification mechanisms for both samples under different conditions were revealed by calculating the effective stress exponent and apparent activation energy. According to regression coefficients for different grain growth exponents, the dominated growth mechanisms for SiC and TiB 2 grains were also explored. [ABSTRACT FROM AUTHOR]

A nanograin (Gd 2 Hf 2 O 7 , GHO) ceramic is prepared using a sol-gel and cold-pressing sintering method as a potential curing matrix material for the high-level radioactive waste (HLW). The microstructure, phase evolution, Raman spectra and aqueous durability of the nanograin GHO samples are comprehensively studied. Results show that the sintered powder of the GHO ceramic undergoes a transition from defective fluorite to a pyrochlore structure in the process of increasing the sintering temperature from 1273 to 1673 K. As the pressing pressure increases from 5 to 30 MPa, the density of the GHO sample increased from 7.25 to 8.25 g cm−3, and the corresponding open porosity decreases from 7.61 to 3.95%. XRD, Raman, and microstructure analysis confirmed that the GHO sample pressed at 30 MPa and sintered after 1673 K exhibits a typical nanograin pyrochlore structure with an average grain size of 167 nm. The normalized release rates of Gd and Hf elements in the optimized GHO sample after 42 days are 6.7 × 10−6 g m−2 d−1 and 7.9 × 10−7 g m−2 d−1, respectively, which exhibited good aqueous durability. The results can provide an alternative candidate for the development of HLW curing matrix material with enhanced environmental stability. [ABSTRACT FROM AUTHOR]

A ceramic core of network-structured ZrSiO 4 surrounding large particles of fused quartz was designed. Experimental results show that the ceramic core prepared by digital light processing (DLP)-3D printing technology, nano-sized ZrO 2 reacting with large SiO 2 particles to generate network-structure ZrSiO 4 in the process of re-sintering. The network structure significantly improves the bending strength of the core while maintaining a high porosity. The stable Al 2 O 3 in the core improved the high-temperature strength of the ceramic core. This is the first study on designing the microstructure of ceramic cores using stereolithography 3D printing technology. The study provides a new idea on the additive manufacturing of ceramic cores. [Display omitted] [ABSTRACT FROM AUTHOR]

By chemical substitutions with Ba2+ and La3+ at A-site in PbHfO 3 -based ceramics, an ultrahigh energy storage efficiency of 91% and high energy density of 7.3 J cm−3 are achieved simultaneously at 290 kV cm−1 in Pb 0.925 Ba 0.045 La 0.03 (Hf 0.6 Sn 0.4) 0.9925 O 3 ceramics. [Display omitted] Near-zero remanent polarization, high breakdown electric field, high saturation polarization and low electrical hysteresis are necessary conditions for antiferroelectric ceramics to obtain excellent energy storage performance. Here, Pb 0.925 Ba x La 0.075−x (Hf 0.6 Sn 0.4) 0.98125+x/4 O 3 lead-based antiferroelectric ceramics were prepared by a rolling process. The composition modulations of Ba and La are beneficial to adjust the phase switching field, improve the saturation polarization and reduce the electrical hysteresis, leading to an enhanced energy storage performance. Simultaneously, the Pb 0.925 Ba 0.045 La 0.03 (Hf 0.6 Sn 0.4) 0.9925 O 3 ceramic exhibited a high energy storage density of 7.3 J cm−3 and an energy storage efficiency of 91%, revealing that this composition is an outstanding candidate in pulsed energy storage application and lays a foundation for further study on the energy storage performances of PbHfO 3 -based antiferroelectric ceramics. [ABSTRACT FROM AUTHOR]

High-density (∼99.34%), fine-grained (∼685 nm) ZnO ceramic was successfully fabricated by the high-pressure cold sintering. The influences of solvent (liquid phase) fraction and the applied pressure on densification in this process have been carefully studied. The excess solvent can result in grain refinement, but impedes the densification of ceramic. Significantly, the role of pressure is unlike that in the traditional pressure-assisted sintering, which can improve the densification and inhibit grain growth. There is a critical pressure (∼1 GPa) that can be associated with the transition of recrystallization from heterogeneous nucleation to homogeneous nucleation. When the pressure is lower than this critical value, the applied pressure can improve densification, but cannot inhibit grain growth. Above the critical value, the densification is dramatically weakened and many small crystals in the interstitial space between grains can be found. [ABSTRACT FROM AUTHOR]

This study introduced a novel low-loss tungstate ceramic, La 7 Nb 3 W 4 O 30 (LNWO), synthesized using the solid-state techniques. The structural analysis of the La 7 Nb 3 W 4 O 30 ceramic material, utilizing X-ray diffraction (XRD) patterns and followed by detailed structural refinement, validated its rhombohedral structure. Transmission electron microscopy (TEM) was utilized to confirm the ordered layer arrangement characteristic of the rhombohedral structure. The internal structure was characterized by scanning electron microscopy (SEM), with the sample's relative density reaching 97.5 %. The correlation between the full width at half maximum (FWHM) of the Raman matrix at 901 cm−1 corresponding to the symmetric bending mode vibrations of WO 5 and the Q × f value was discussed. Furthermore, the main factors affecting the dielectric constant, including density, bond valence, secondary phases, and variations in porosity, were analyzed. Encouragingly, the ceramic showed significant microwave dielectric properties when it was sintered at 1425 °C (ε r = 23.68, Q × f = 26,687 GHz (f = 7.2 GHz), τ f = −35.2 ppm/°C). [ABSTRACT FROM AUTHOR]

A novel Li 4 AlSbO 6 (LASO) microwave dielectric ceramic with a monoclinic structure and space group C12/c1 was successfully prepared using traditional solid-state methods. When the sintering temperature was 1200 °C, it had excellent microwave dielectric properties, with ε r = 8.2, Q × f = 22,098 GHz, and τ f = −15.53 ppm/°C. Raman spectroscopy analysis showed that the FWHM of the strong peak at 691 cm−1 reflected the variation trend of Q × f value and was opposite to the variation trend of Q × f value. Additionally, the augmentation in the Q × f value can be attributed to a higher relative density. As per the bond valence analysis, ε r is closely connected to the rattling and compressing effects of A-site cations, and the higher ε theo than ε r in Li 4 AlSbO 6 can be attributed to the strong compression effect induced by Li+. Additionally, τ f may be influenced by both the Sb–O bond and relative density. [ABSTRACT FROM AUTHOR]

In this study, we prepared a novel series of Li 2 x Cu 1- x MoO 4 (x = 0.02, 0.04, 0.06, 0.08, and 0.10) microwave ceramics. The dynamic sintering behavior, crystal phases, micro-morphologies, and dielectric properties of the samples were studied. The substitution of Li+ contributed to refining the crystal grain size, promoting the densification of microstructure, and enhancing the quality factor. Due to different valence substitutions, Cu+ ions were created, which were verified by X-ray photoelectron spectroscopy (XPS) and Raman experiments. In addition, the Raman shift, full width at half maximum (FWHM) value of the A 1g peak, and crystal microstrains were analyzed to gain a mechanistic understanding of the influence of structure on the dielectric properties. When x = 0.08, the Li 2 x Cu 1- x MoO 4 ceramic sintered at 675 °C exhibited optimal comprehensive properties with ε r = 8.17, Qf = 68 476 GHz, and τ f = −25 ppm/°C, and good chemical stability between the ceramic and Al electrode was also achieved. These promising properties make Li 2 x Cu 1- x MoO 4 (x = 0.08) more suitable for ultra-low temperature co-fired ceramic (ULTCC) applications. [ABSTRACT FROM AUTHOR]

A novel Li 3 Mg 4 NbO 8 compound was fabricated through the process of solid-state reaction. The crystal structure, sinterability and microwave dielectric properties of the Li 3 Mg 4 NbO 8 ceramics were investigated. XRD refinement and Raman spectra results ascertained that the Li 3 Mg 4 NbO 8 compound crystallized into an orthorhombic Li 3 Mg 2 NbO 6 -like structure with space group Fddd. The ε r value was strongly impacted by the relative density and average ionic polarization. The Q × f value was mainly affected by the relative density and average grain size. The Li 3 Mg 4 NbO 8 ceramics sintered at 1150 ℃ showed outstanding microwave dielectric performance: ε r = 13.8 ± 0.14, Q × f = 103 400 ± 3500 GHz (at 9.6 GHz), τ f = −36.0 ± 1 ppm/℃. Additionally, the bond characteristics were calculated for a better understanding of the structure-property correlation for Li 3 Mg 4 NbO 8 ceramics. [ABSTRACT FROM AUTHOR]

The properties of ceramic slurry play a crucial role in the production of high-quality ceramic cores. In stereolithography 3D printing process, ceramic slurry should have high solid loading as far as possible. In this work, slurry with high solid loading and low viscosity was successfully prepared by changing the resin composition. When HDDA:TMPTA was 6:2, slurry exhibited low viscosity, high stability and excellent curing properties. Ceramic cores were successfully prepared by the optimized slurry with a solid loading of 60 vol%. The effects of sintering temperature on ceramic cores were studied. As the increase of sintering temperature, the bulk density gradually increased and the open porosity decreased. The ceramic cores exhibited excellent properties at 1250 °C. This work provided a theoretical basis for the optimisation and application of slurry on stereolithography 3D printing ceramic cores. [Display omitted] [ABSTRACT FROM AUTHOR]

The temperature enduring capacity of turbine blades determines the thrust-weight ratio of aero-engines. The heat dissipation efficiency of blades is improved mainly through designing complex internal cooling channel. As a transitional component of blade preparation, the shape of ceramic cores has become gradually complex. The traditional process is difficult to meet the preparation requirements of ceramic core with complex structure due to the limitation of mold. Stereolithography 3D printing provides a feasible technology for the preparation of ceramic cores with complex structures. The key to high-performance ceramic core via the stereolithography 3D printing lies in the prepare ceramic slurry with high solid loading, low viscosity and uniform stability. Choosing suitable dispersant is an effective way to prepare above standard slurry. In this study, the effects of single and dual dispersants on the rheological properties of ceramic slurry were systematically investigated. The action mechanism of the dispersant was analyzed. The functional relationship between solid loading and viscosity was elucidated. The silicon-based ceramic core slurry with 70 vol% solid loading and viscosity of 10520 mPa s (12.6 s−1) was obtained. Through optimizing printing parameters, the complex structure silicon-based ceramic core was fabricated. The influence of solid loading on the microstructure and physical properties of the ceramic core was investigated. The results show that with the increase of solid loading, the shrinkage of ceramic core lowers and the flexural strength of ceramic core strengthens. The successfully preparation of complex structure ceramic core based on high solid loading slurry promotes the extensively implemented of stereolithography 3D printing technology in the field of ceramic core. [Display omitted] [ABSTRACT FROM AUTHOR]