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In this work, stacked SiC fibers paper‐reinforced SiC ceramic matrix composites (SiCnf/SiC CMCs) were prepared by nanoimpregnation and transient eutectic (NITE) process using ultra‐long single‐crystal SiC nanofibers. The effect of the SiCnf surface modification via boron nitride (BN) interphase deposition as well as the sintering additive (Al2O3–Y2O3) content on the density, microstructure, and mechanical properties of SiCnf/SiC CMCs has been investigated systematically. The results revealed that the laminated SiCnf/SiC CMCs feature a significant saw‐tooth‐like curve on the load–displacement test, which indicates that the obtained laminated structure with the weak interlayer binding owning to the BN coating treatment possesses significant toughening to the SiC ceramics. Specifically, the SiCnf/SiC CMCs with the sintering additive content of 12 wt% revealed a fracture toughness of over 10 MPa m1/2 after 60 min of BN interface deposition, which is 104.31% higher than that of the composites prepared without BN coating. [ABSTRACT FROM AUTHOR]

The small‐signal dielectric and piezoelectric coefficients of paper‐derived sodium potassium niobate, K0.5Na0.5NbO3 (KNN), were compared with those of conventionally prepared samples. Results show similar functional properties of paper‐derived KNN without significantly decreasing the small‐signal piezoelectric coefficient. The structure and microstructure analysis of conventional KNN and paper‐derived KNN did not reveal any significant difference in the crystal structure and grain size. However, the temperature‐dependent inter‐ferroelectric phase transition temperature estimated from the temperature‐dependent dielectric permittivity data revealed a decrease of approximately 18°C for the paper‐derived KNN and is possibly associated with the structural and microstructural defects. This work indicates that optimizing suspension chemistry and sintering conditions will be critical to enhance the functional response of paper‐derived KNN further. Moreover, paper‐derived ceramic processing, a novel and cost‐effective additive manufacturing technology, can be potentially used to fabricate other electroceramics with a wide range of porosities and sizes as well as complex geometries and multilayer structures. [ABSTRACT FROM AUTHOR]

SiFeO(N,C)‐based ceramic papers were prepared via a one‐pot synthesis approach by dip‐coating a cellulose‐based paper template with a polymeric perhydropolysilazane precursor modified with iron(III)acetylacetonate. The preceramic composites were subsequently pyrolyzed in ammonia atmosphere at 500, 700, and 1000°C, respectively, and the characteristics of the three resulting ceramic papers were comparatively investigated. Scanning electron microscopy revealed that in each sample, the morphology of the template is successfully transferred on the ceramic system, with the cellulose‐derived fibers being converted to elemental carbon encased by a SiFeO(N,C) coating. Electron transparent cross‐sectional samples for transmission electron microscopy (TEM) were prepared from the ceramic papers, employing a standard ultramicrotomy slice cutting procedure, allowing for a detailed characterization of their in situ generated micro‐/nanostructure as well as occurring crystalline phases. TEM imaging and diffraction revealed that depending on pyrolysis temperature a different microstructure with a distinct phase assemblage is generated in the polymer‐derived ceramic papers. Crystallization from the polymer precursor starts with the precipitation of wüstite (Fe(1‐x)O) nanoparticles at 700°C inside the ceramic coating and secondary ε‐FexN at the fiber‐coating interface. Upon pyrolysis at 1000°C however, the sample primarily accommodates metallic α‐iron nanocrystals that impart ferromagnetic characteristics to the ceramic paper. The results show that the template‐assisted polymer‐derived ceramic route is a feasible approach in the production of complex ceramic compounds with fibrous paper‐like morphology. By adjusting the pyrolysis temperature, microstructure and phase composition of the ceramic paper can be conveniently tailored to the needs of its respective application. [ABSTRACT FROM AUTHOR]

In this paper, two new ternary layered MAX phase ceramics, Sc2GaC and Sc2InC, were successfully synthesized by spark plasma sintering. The crystal structures of two new compounds were determined by X‐ray diffraction. The lattice parameters were a = 3.3609(0) Å and c = 14.5849(9) Å for Sc2GaC, and a = 3.3453(6) Å and c = 15.2236(3) Å for Sc2InC, wherein the Sc atoms were located at (1/3, 2/3, 0.07330[Ga]/0.08268[In]), the A atoms were located at (1/3, 2/3, 3/4), and the C atoms were located at (0, 0, 0). Scanning electron microscopy images of two new MAX phase ceramics were also given in this paper, showing obvious layered characteristics. [ABSTRACT FROM AUTHOR]

Phosphors doped with Mn4+ ions have strong emission in the red and far‐red light regions and are therefore used as red phosphors for indoor plant cultivation light‐emitting diodes (LEDs) and white LEDs (w‐LEDs). This paper introduces La2Mg(Mg1/3Ta2/3)O6: Mn4+ (Mg2La3TaO9: Mn4+) red phosphors prepared by conventional high‐temperature solid‐phase method. The broad excitation band of Mg2La3TaO9: Mn4+ phosphor is effectively excited by ultraviolet and blue light in the range of 250–600 nm, with the emission of 707 nm centered on far‐red light. The phosphor has a high color purity of 99.07% and an internal quantum efficiency of 59.87%. To further enhance the performance of the phosphor, a cation substitution method was adopted in this paper to synthesize La2Mg(Al1/2Ta1/2)O6: Mn4+ phosphor by replacing [1/3Mg2+–2/3Ta5+] in La2Mg(Mg1/3Ta2/3)O6: Mn4+ with [1/2Al3+–1/2Ta5+]. The luminescence intensity and thermal stability of the samples were enhanced. The emission spectrum of the Mg2La3TaO9: Mn4+ samples matched well with the phytochrome PFR (phytochrome that absorbs far‐red light) and is suitable for the preparation of LEDs for indoor plant cultivation. The concentration quenching effect of the samples was investigated, the main mechanism of which is the electric dipole–dipole interaction. Red LEDs and w‐LEDs devices were prepared with the synthesized phosphors that produce light stably at different currents. The w‐LEDs have a correlated color temperature of 5310 K and a color rendering index of 80.1. Therefore, these samples are expected to be used as red components for w‐LEDs. [ABSTRACT FROM AUTHOR]

This paper investigates the phase evolution and pulverization mechanism of a self‐pulverizing carbonatable clinker (SPCC) with a variety of raw material compositions. The particle size, mineral phases, and microstructure of SPCC, produced by sintering at 1400°C for 3 h, were systematically studied by laser particle size testing, XRD/QXRD and SEM/EDS. Results show that clinkers sintered by raw materials with low‐Ca/low‐Al (Ca/Si < 1.6; Al2O3 < 10 wt.%) or high‐Ca/medium‐Al (Ca/Si > 2.6; Al2O3 ≈ 10 wt.%) are non‐pulverized after cooling. The mineral phases of C2AS, CA, and C12A7 are considered to facilitate clinker pulverization at low γ‐C2S contents. With the increase of Al2O3 content in raw materials, SPCC is refined in particle size, accompanied by the significant decrease in the content of calcium silicates. Based on the results, guidelines for producing SPCC are proposed. [ABSTRACT FROM AUTHOR]

B Cover Photograph b : Atomic force microscopy topographies and scanning electron microscopy (inserts) images depict the rationally designed interfaces to mitigate the photogenerated charge losses in the hematite photoanode. B Image Credit b : Images are partially modified from the paper Bedin, K.C., Rodríguez-Gutiérrez, I., Peregrino, L.R.P., Vayssieres, L. and Souza, F. L. Souza. On electron loss lowering at hematite photoelectrode interfaces. [Extracted from the article]

[Ca24Al24.08Zr3.92O64]4+(4e−) electrides are ceramic materials with low work functions that can store high‐density free electrons. So, it has great application potential in electron emission. In this paper, The mixed powders of CaO, Al2O3, ZrO2, and Al in a certain stoichiometric ratio were used as precursors, and [Ca24Al24.08Zr3.92O64]4+(4e−) blocks were fabricated through in‐situ reduction. The synthetic block samples have fewer pores, cracks, and impurities, and the blocks' relative density reaches 99.6%. At the same time, the blocks' cages were injected with high‐density electrons during the sintering, and the electron density reached 2 × 1021 cm−3. This makes the sample realize the transition from insulation to conductor. In addition, the block's emission current and effective work function is 1.75 A/cm2 and 2.25 eV, respectively, at 1100°C. The research in this paper provides a new way for the low‐cost and industrial production of high‐quality [Ca24Al24.08Zr3.92O64]4+(4e−). [ABSTRACT FROM AUTHOR]

Helium (He) exerts significant influence on the physicochemical, structural, and electronic properties of pyrochlores. This paper reviews recent advancements in computer simulations aimed at stabilizing nuclear waste, focusing on disordered structures of pyrochlores, zirconate pyrochlores, and high‐entropy pyrochlores. Using Pu‐La2Zr2O7 as a case study, we demonstrate how a first‐principles approach facilitates the understanding of how He modifies the structural and electronic properties of this system. The incorporation of He interstitials in Pu‐La2Zr2O7 typically leads to an expansion in lattice constant and volume swelling. Analysis of the formation energies in this system reveals that octahedral interstitial sites or zirconium (Zr) vacancy sites are favored for He occupation, resulting in the formation of substitutional He atoms. The low concentration of He atoms in Pu‐La2Zr2O7 reduces the formation energy of cation antisite defects. Bader charge analysis indicates that the < Zr‐O > bond exerts a greater influence on the irradiation resistance of the He‐Pu‐La2Zr2O7 system compared to the < La‐O > bond. Moreover, the capacity for He interstitials increases with higher Pu concentration in the octahedrons. [ABSTRACT FROM AUTHOR]

Toward expanding the application of fly ash in cement‐based materials, this study proposes a comprehensive study on predicting the elastic properties of low‐volume fly ash concrete, with the replacement levels limited to 30% or less. Unlike conventional ordinary Portland cement concrete, the inclusion of fly ash in concrete brings alterations in properties from both chemical and physical perspectives: (1) the presence of fly ash liberates the alkaline solution that consumes calcium hydroxide to generate secondary calcium silicate hydrate gels; (2) unreacted fly ash particles exhibits a refinement effect on the micropore structure and contributes to forming a denser solid matrix. In order to characterize these effects on the mechanical properties of fly ash concrete, this paper conducts qualitative assessment of hydration reactions and quantitative calculations of volumetric compounds in the material. Utilizing the Mori‒Tanaka scheme, a predictive model is then developed to integrate the hierarchical effects of constituents at multiple scales on the modulus of elasticity of low‐volume fly ash concrete. The reliability of the proposed model is validated through a series of mechanical tests involving various mix designs, as well as comparison with other published test data. [ABSTRACT FROM AUTHOR]

High‐temperature piezoelectric sensing is usually used in the aerospace, automotive, and power plant fields. High temperature piezoelectric ceramics are considered the key materials in these fields. In this paper, Ca1−x(Ba1/2Sr1/2)xBi2Nb1.985(W3/4Mn1/4)0.015O9 (x = 0.05, 0.10, 0.15 and 0.20) (C1−xBSxBNWM) has been synthesized by a traditional solid state reaction method. The effects of substitution of calcium at the A‐site by barium and strontium on phase evolution and piezoelectric properties of the CaBi2Nb2O9 orthorhombic Aurivillius phases were investigated. The crystal structure of piezoelectric ceramics was characterized by XRD, Rietveld refinement, and Raman spectroscopy. Co‐substitution of barium/strontium (Ba2+/Sr2+) and tungsten/manganese (W6+/Mn4+) resulted in lattice distortion of C1−xBSxBNWM ceramics. The results induce that the tetragonal crystal structure increase with increasing the co‐substitution cations. Isothermal impedance spectroscopy confirmed intrinsic thermally activated conduction in the system. The C1−xBSxBNWM ceramics with x = 0.15 exhibit a very high Curie temperature (TC ∼ 923°C), a reasonable piezoelectric coefficient (d33 = 13.3 pC/N). Remarkably, even after thermal annealing at temperatures up to 800°C, it still retains a high d33 of 13 pC/N. In addition, the C0.85BS0.15BNWM ceramic had a relatively high resistivity (3.82 × 106 Ω·cm, 500°C). The Ca0.85(Ba1/2Sr1/2)0.15Bi2Nb1.985(W3/4Mn1/4)0.015O9 ceramics make possible their application in high‐temperature acceleration transducers. [ABSTRACT FROM AUTHOR]

In this paper, we investigated the effect of processing parameters and composite regulation on the structure and property relationship of lightweight low‐permittivity Li2O–Al2O3–B2O3 dielectric system. Li2BAlO4 ceramic and (1 − x)Li2BAlO4–xSrTiO3 ceramics were synthesized using a conventional solid‐state reaction method. Thermodynamic analysis, sintering temperature, phase formation, crystal structure, and microwave dielectric properties were investigated. Thermal analysis revealed a melting temperature of 847°C, suggesting a comparatively low temperature for the sintering of Li2BAlO4 ceramics. Li2BAlO4 crystalized into a monoclinic structure with P21/c space group, with [Al2B2O8] rings connected by [BO3] triangles and [AlO4] tetrahedra through Al–O–Al bridges. Dense Li2BAlO4 ceramics with a relative density of ∼97.7% were sintered at 750°C and had optimal microwave dielectric properties with relative permittivity (εr) of 5.13, quality factor (Q × f) of 22 610 GHz, and the temperature coefficient of resonance frequency (τf) of −112.5 ppm/°C. The 0.88Li2BAlO4–0.12SrTiO3 composite ceramic has excellent microwave dielectric properties with εr = 8.83, Q × f = 14 000 GHz, τf = 4.6 ppm/°C. The ceramics also demonstrated an inert behavior with silver electrodes proving its application in low‐temperature cofired ceramic (LTCC) technology. [ABSTRACT FROM AUTHOR]

In this paper, we investigated the effect of processing parameters and composite regulation on the structure and property relationship of lightweight low‐permittivity Li2O–Al2O3–B2O3 dielectric system. Li2BAlO4 ceramic and (1 − x)Li2BAlO4–xSrTiO3 ceramics were synthesized using a conventional solid‐state reaction method. Thermodynamic analysis, sintering temperature, phase formation, crystal structure, and microwave dielectric properties were investigated. Thermal analysis revealed a melting temperature of 847°C, suggesting a comparatively low temperature for the sintering of Li2BAlO4 ceramics. Li2BAlO4 crystalized into a monoclinic structure with P21/c space group, with [Al2B2O8] rings connected by [BO3] triangles and [AlO4] tetrahedra through Al–O–Al bridges. Dense Li2BAlO4 ceramics with a relative density of ∼97.7% were sintered at 750°C and had optimal microwave dielectric properties with relative permittivity (εr) of 5.13, quality factor (Q × f) of 22 610 GHz, and the temperature coefficient of resonance frequency (τf) of −112.5 ppm/°C. The 0.88Li2BAlO4–0.12SrTiO3 composite ceramic has excellent microwave dielectric properties with εr = 8.83, Q × f = 14 000 GHz, τf = 4.6 ppm/°C. The ceramics also demonstrated an inert behavior with silver electrodes proving its application in low‐temperature cofired ceramic (LTCC) technology. [ABSTRACT FROM AUTHOR]

In this paper, macroporous high‐entropy spinel oxide (HESO) (Fe0.2Ni0.2Co0.2Mn0.2Zn0.2)3O4 monoliths were successfully fabricated via a sol–gel method followed by calcination. Appropriate polyacrylic acid and propylene oxide contents allow the formation of three‐dimensional co‐continuous xerogel monoliths, and the water/glycerol ratio controls the macropore size of monoliths. Subsequent calcination achieves the precipitation of HESO (Fe0.2Ni0.2Co0.2Mn0.2Zn0.2)3O4 with a singular phase and exceptional structural stability. The macroporous HESO (Fe0.2Ni0.2Co0.2Mn0.2Zn0.2)3O4 demonstrates remarkable performance in the oxygen evolution reaction (OER) with an overpotential of 333 mV at 100 mA cm−2 and a Tafel slope of 43.2 mV dec–1, surpassing that of RuO2 (391 mV) under identical conditions. Furthermore, the catalytic stability of the HESO catalyst remains superior even after 24 h of testing. This process offers a promising avenue for the development of macroporous high‐entropy oxide OER catalysts for overall water splitting. [ABSTRACT FROM AUTHOR]

ABSTRACT Low‐εr (the low dielectric constant) microwave dielectric ceramics play an important role in sub‐6 GHz band communication by virtue of their small signal delay. In this paper, Ba2CoSi2O7 ceramics were synthesized by the solid‐phase reaction method, and X‐ray diffraction (XRD) confirms that they belong to a new melilite structure, with C2/c (No.15) space group, and the ceramics have good microwave dielectric properties with an εr ∼ 7.37, a Q×f (Q = 1/dielectric loss, f = resonant frequency) ∼ 26,320 GHz and a TCF (the temperature coefficient of resonant frequency) ∼ −55 ppm/°C after being sintered at 1150°C, and the theoretical dielectric constants derived from the Clausius–Mosotti as well as the porosity equation, respectively, are also used to further demonstrate the low‐εr properties. Based on the group theory, the one‐dimensional integrable representations of Γacoustic (the phonon modes) and Γoptical (optical modes) of Ba2CoSi2O7 are obtained, and the internal vibrational modes of Ba2CoSi2O7 are deconstructed and the main modes of influence of the electronic polarization are analyzed in conjunction with the results of the validly fitted peaks of the 17 Raman and 25 IR tests. A microstrip Yagi antenna is also designed based on the ceramic properties, which can achieve a gain of 9.65 dBi at the center tuning frequency of 5.47 GHz, with a S11 (return loss) close to −60 dBi. Based on the above results, the Ba2CoSi2O7 ceramic is a low‐εr microwave dielectric ceramic with significant potential for communication application. [ABSTRACT FROM AUTHOR]

Defect chemistry that results in the thermal processing of dielectric and piezoelectric films, crystals and ceramics ultimately controls the properties and long‐term performance of materials and devices. This paper reviews several thermochemical defect reactions using important perovskite base composition dielectrics including Pb(Zr,Ti)O3, (Na,K)NbO3, (Bi0.5Na0.5)TiO3‒BaTiO3, and Ca(Hf,Ti,Mn)O3. Within this group of perovskite‐based functional materials, we note ways the point defects can be formed to create non‐stoichiometric compositions changing the overall cation‐to‐anion ratios during the synthesis process. These reactions can be developed with the loss of volatile species such as metal and oxygen ions. The relative concentrations of these can impact the over conductions in terms of the mixed contributions of ionic conductivity from the oxygen vacancies and the electronic conductivity, along with microstructure and properties in some cases. [ABSTRACT FROM AUTHOR]

In this paper, a new micromechanical hysteresis loop constitutive model of C/SiC composites with different interphases was developed considering the probabilistic‐statistical matrix fragmentation process. The lengths of matrix fragmentation were divided into three types, that is, long matrix fragments (LMFs), medium matrix fragments (MMFs), and short matrix fragments (SMFs). The distributions of the LMFs, MMFs, and SMFs with increasing tensile stress were determined using the probabilistic‐stochastic model by assuming the two‐parameter matrix strength distribution. The micro stress field of the LMFs, MMFs, and SMFs upon unloading and reloading was obtained and adopted to determine the corresponding stress‐strain relations. The interaction of matrix fragmentation lengths, especially for the LMFs with large debonding energy (LDE) and SMFs, was considered in the closed‐form constitutive model and hysteresis‐based inverse tangent modulus (ITMs) damage parameter. Synergistic effects of the fiber volumes, peak stresses, and interface debonding energy on the interface damage state, mechanical hysteresis loops, and related ITMs with small debonding energy and LDE were also analyzed. Comparisons of the mechanical hysteresis loops using the new hysteresis models considering matrix stochastic fragmentation and hysteresis models considering constant matrix fragmentation were also discussed. Experimental cyclic tensile hysteresis loops and unloading/reloading ITMs of C/(PyC)/SiC and C/(PyC+SiC)/SiC composites with different interphase thickness (i.e., t = 300, 600, 1000, and 2000 nm) were predicted using the developed constitutive model. Evolution of the unloading/reloading interface slip ratio was analyzed for different tensile peak stresses. [ABSTRACT FROM AUTHOR]

In situ metallization of Ag+ conductive glass was successfully achieved by applying electric and temperature fields to the glass to ensure the controlled migration of ions inside the glass. The transport and kinetic characteristics of Ag+ under the combined effect of electric field and temperature field were investigated by calculating and analyzing Ag+ diffusion coefficient. The correlations between ion transport and current were characterized with potential energy equations. The simulations and experiments of ion transport in the conducting glass were implemented, which revealed the mechanisms of ion transport and interfacial precipitation within the conducting glass. Further more, the existence of Ag+ deprivation layer was confirmed and it was clarified that the depth of the deprivation layer reached 30 µm under thermal polarization conditions of 60 V and 300°C. The microscopic morphology of in situ silver deposition layer was observed using SEM and TOF–SIMS. In addition, It was determined that the in situ metallization of conductive glass under the polarization condition of 60 V at 250°C was the best, and the thickness of deposited silver dendrites reached 1000 nm in the side of cathodically. This paper provides theoretical and experimental references for the optimization of the in situ metallization process for the ion conductive glass. [ABSTRACT FROM AUTHOR]

Increasing the active site of redox reactions on the surface of photocatalysts and accelerating the separation and transfer of photogenerated electron‐hole pairs are effective methods to improve the hydrogen evolution of composite photocatalysts. Non‐precious metal Ni photo‐deposition is anchored in situ on the ZnIn2S4 surface to generate the cocatalyst Ni(OH)2, which improves the photocatalytic hydrogen evolution performance of the composite sample. Under visible light irradiation, the ZnIn2S4 semiconductor stimulates photon‐generated carriers. Ni2+ acts as the defect center of photogenerated electron‐hole pairs to promote the separation of carriers. It serves as the capture site of light‐generated holes to reduce the carrier recombination rate so that the light‐generated electrons on the ZnIn2S4 surface promote H+ reduction in H2. Ni(OH)2 provides the active site for oxidation reaction on the surface of semiconductor materials, allowing the carrier to be consumed faster and improving the photocatalytic stability of semiconductor materials. The addition of 2 wt% Ni2+ resulted in a hydrogen evolution rate of 10 066 µmol·g−1 ·h−1 for ZnIn2S4/Ni(OH)2, which was 2.5 times higher than that of pure ZnIn2S4. This paper presents a reference case for enhancing the stability of sulfide to promote its photocatalytic hydrogen evolution. [ABSTRACT FROM AUTHOR]

In this paper, Ni was introduced into the matrix of carbon fiber reinforced SiOC (C/SiOC) composites by the precursor infiltration and pyrolysis method to catalyze the generation of in situ formed nanostructures including carbon nanotubes (CNTs), turbostratic carbon, and SiC. The effect of in situ formed nanostructures catalyzed by Ni on the properties of the C/SiOC composites was investigated. The results demonstrated that the presence of in situ formed nanostructures in the matrix improved the densification and mechanical properties of C/SiOC composites. In addition, the incorporation of in situ formed nanostructures facilitated the formation of thermal conductivity pathways within the composites, thereby enhancing the thermal conductivity of C/SiOC composites. Furthermore, in situ formed nanostructures‐containing C/SiOC composites developed a carbon friction layer comprising CNTs and turbostratic carbon, which significantly enhanced the abrasion resistance, endowing C/SiOC composites stable friction coefficients, and lower levels of wear. [ABSTRACT FROM AUTHOR]

In ceramic injection molding, the conventional solvent‐debinding process encounters limitations such as solvent cost and environmental pollution. In this paper, a suitable thermal‐debinding process from room temperature to 250°C using carbon/alumina embedding powders with nano and submicron size was developed to remove the soluble binders replacing the conventional solvent debinding of injection molding ZrO2 ceramic. The effects of the embedding powders on microstructure and debinding ratio were studied in detail. The results showed that the main factor influencing debinding ratio was associated with the sufficient dispersing of mixed particles, which was characterized by the relative change ratio of tap volume. A debinding mechanism was proposed to explain the effects of carbon/alumina mixed powders on the debinding ratio and surface cracks. Based on the influencing mechanism, the debinded green part with the elimination of soluble binders and optimal surface was achieved using the mixed powders with C/A = 8/2 on the top and C/A = 4/6 on the bottom. [ABSTRACT FROM AUTHOR]

Powder synthesis is crucial for achieving the densification and facilitating widespread applications of high entropy carbide (HEC). Specifically, the production of fine particle‐size powders is essential to enhance the densification of HECs. Consequently, this paper proposes the molten salt method for synthesizing HEC powders. The synthesis process successfully yielded (Ta Nb Ti V) C powders with a particle size of only 0.44 µm at 1400°C, exhibiting a uniform distribution of each element. Subsequent densification of (Ta Nb Ti V) C within the 1700–1900°C temperature range was carried out using spark plasma sintering. It was observed that as the densification temperature increased, the densification and mechanical properties of HEC significantly improved. This study presents innovative ideas for the preparation of HEC at lower temperatures. [ABSTRACT FROM AUTHOR]

Ytterbium disilicate (Yb2Si2O7) is a potential environmental barrier coating (EBC) material. In this paper, the microstructure and phase composition of plasma‐sprayed Yb2Si2O7 coatings with different spraying process were systematically investigated to optimize the spraying power and spraying distance. Furthermore, in order to obtain Yb2Si2O7 coating with single phase, a certain proportion of SiO2 was added to the Yb2Si2O7 powder to compensate for the volatilization of SiO2 during plasma‐spraying process, and the influence of spraying powder composition on the microstructure and phase structure (composition and content) of Yb2Si2O7 coatings were also characterized in detail. The results showed that the Yb2Si2O7 coating was dense with fewer pores and cracks at the spraying power of 40 kW and the spraying distance of 100 mm. Yb2Si2O7 coating with the "sandwich" structure was composed of Yb2Si2O7, Yb2Si2O7 + Yb2SiO5, and Yb2SiO5 three microstructures, which was mainly caused by the volatilization of SiO2 in Yb2Si2O7 spraying powder. The Yb2Si2O7 coating contained 90.68 mol.% Yb2Si2O7 phase and 9.32 mol.% Yb2SiO5 phase after crystallization at 1300°C for 20 h. The coating was composed of Yb2Si2O7 phase and amorphous phase after SiO2 addition. Yb2SiO5 phase precipitated from the coating after heat treatment at 1300°C, and its content decreased with the increase of SiO2 content. The content of the Yb2Si2O7 phase was as high as 99.41 mol.% when SiO2 content was 10 mol.%, which would provide a scientific basis for further research on stoichiometric Yb2Si2O7 EBCs with excellent properties. [ABSTRACT FROM AUTHOR]

A large adiabatic temperature change along with a wide operating temperature region is usually required for the electrocaloric materials to fulfill their refrigeration function. In general, doping foreign ions into BaTiO3 is the frequently utilized strategy in order to obtain excellent electrocaloric materials for the practical application. In the current paper, BaTiO3 lead‐free ferroelectric ceramics were doped by Ca2+ and Sn4+ simultaneously in order to generate a coexistence state at room temperature, where ferroelectric domains and nanodomains exit. As a result, a large polarization and a wide operating temperature range were finally induced. It is found that Ba0.9Ca0.1Ti0.85Sn0.15O3 has a maximum adiabatic temperature change of 0.85 K and an excellent working temperature region (65 K, ∆T > 90% Tmax) was achieved under an electric field of 50 kV/cm. The above phenomenon indicates that the modified BaTiO3 ceramics can be a good potential electrocaloric material in the state of cross‐existence of ferroelectric domains and nanodomains. [ABSTRACT FROM AUTHOR]

The full matrix parameters of a piezoelectric material are crucial for designing and evaluating piezoelectric devices. However, due to their inverse problematic nature, commonly used single‐sample characterization methods heavily depend on the accuracy of initial values and mode matching. In this paper, we propose a quasi‐31‐vibrator method to directly evaluate these parameters by designing the sample geometry and establishing the relationship equation between the parameters. This approach completely bypasses the need for characteristic spectrum simulation and mode identification processes. Subsequently, we tested the full matrix parameters of PZT‐5H ceramics and compared the simulated impedance spectra with the measured ones. The presence of well‐fitting spectra validates the feasibility of the method. This method will contribute to characterize the parameters of new piezoelectric materials and advance the intelligent implementation of measuring full matrix parameters. [ABSTRACT FROM AUTHOR]

Here, we provide the correct glass transition temperatures for 10°C/min cooling/heating rate-treated samples. Corrigendum to "A tetrad effect in the glass transition of lanthanide-doped sodium disilicate glasses" (J. Am. Ceram. In our paper "A tetrad effect in the glass transition of lanthanide-doped sodium disilicate glasses", rather than plotting values for the glass transition (T SB g sb ) for a matched cooling/heating rate of 10°C/min (as stated in that paper), we erroneously plotted values for the glass transition (T SB g sb ) of first calorimetric runs on glasses "as synthesized" with unknown thermal history (i.e., cooling rate). [Extracted from the article]

A novel method for preparation of ZrB2 coatings has been proposed by combination of molten salt synthesis of ZrB2 nanoparticles and subsequent electrophoretic deposition of the as‐synthesized ZrB2 nanoparticles in the same molten system in this paper. Nanoscale ZrB2 particles have been produced by borothermal reduction of ZrO2 in NaCl‐KCl‐AlF3 melt at 980°C. Then electrophoretic deposition of the as‐synthesized ZrB2 nanoparticles has been achieved in the resulting molten suspension at a reduced temperature of 900°C, yielding relatively dense ZrB2 coatings on graphite substrates with a thickness of around 25 μm. Moreover, the effect of different cell voltages ranging from 0.8 V to 1.4 V (i.e., electric field 0.4–0.7 V/cm) on the prepared ZrB2 coatings has been investigated. Finally, during the tests at 600°C–800°C in air, ZrB2 coatings deposited at a cell voltage of 1.2 V have exhibited good high‐temperature oxidation resistance. [ABSTRACT FROM AUTHOR]

Bismuth layer structured ferroelectrics (BLSFs) have drawn much attention due to their great potential for high‐temperature applications. It is generally accepted that BLSFs with small orthorhombic distortion should have low TC. In this paper, we report an anomalous example Li0.5Bi2.5Nb2O9 (LBN), which has small orthorhombic distortion but very high TC. LBN shows the highest TC (834°C) among currently reported prototype alkali‐metal BLSFs, which is attributed to its small tolerance factor. However, the refinement result reveals that LBN is orthorhombic with the space group of A21am, and the orthorhombic distortion of LBN a/b is merely 1.0019. The measurement of piezoelectric coefficient (d33 ∼ 6 pC/N) and observation of striped domain structure confirm the ferroelectricity nature of LBN. This work deepens our understanding of BLSFs and may lead to the finding of more novel BLSFs with high performance. [ABSTRACT FROM AUTHOR]

Nowadays, the glass transition kinetics is most commonly described in terms of the Tool–Narayanaswamy–Moynihan (TNM) model. Evaluation of one of the most prominent features of the structural relaxation motions—the relaxation nonlinearity—was traditionally done using the peak‐shift (PS) method. This paper introduces, for the first time, extensive testing of the PS method by means of theoretical simulations for all practically observable types of structural relaxation behavior and all types of glassy/amorphous materials (tested range of the glass transition temperatures: −55 to 1000°C; tested range of the relaxation activation energies: 300–1300 kJ⋅mol−1). For the majority of types of structural relaxation behavior, the PS method tends to slightly overestimate the value of the TNM nonlinearity parameter x (by ∼ 0.05–0.10). In the specific cases of the highly linear behavior (↑ x) combined with a broad distribution of relaxation times, the PS method systematically vastly underestimates the value of x. A new, improved temperature program was proposed for the PS method, eliminating the major intrinsic drawback of the originally proposed version of the PS methodology. In addition, based on the comparison between the theoretically simulated and real‐life experimental data, a new approach (based on the characteristic PS dependence shape) was introduced to estimate the width of the relaxation times distribution. [ABSTRACT FROM AUTHOR]

Noncontact temperature measurement using thermochromic materials is vital in the field of temperature indication, but the related mechanisms behind thermochromic behavior are diverse and high complexity, and the color‐temperature correspondence is poorly explored. This paper systematically studied the thermochromic mechanisms and color‐temperature correspondence in the cobalt‐doped LaCrO3 coatings via experiment and density functional theory study. The coatings appear reversible thermochromism from green to black with temperature and composition, functions from room temperature to 700°C. This thermochromism is attributed to the lattice expansion and bandgap reduction as the temperature increase, and a model of temperature effect bandgap was proposed. Meanwhile, the coating temperature can be inferred from the color change because the CIE chromaticity coordinate of the coating varies linearly with temperature, and the mean relative error of thermochromic measurements is 8.28%. Furthermore, the cobalt doped introduces impurity energy levels and enhances the interaction between photons and carriers, which reduce the bandgap and increase the absorption in the visible spectrum resulting in darker colors. This work provides a stable and efficient high‐temperature thermochromic coating that has a wide thermochromic temperature range and clear color‐temperature correspondence, which shows broad application prospects in the field of thermal indication at high temperatures. [ABSTRACT FROM AUTHOR]

Single‐crystal core multimaterial fibers have a wide range of applications in optics. Though some multimaterial fibers with single‐element crystal cores have been manufactured successfully, the preparation of binary and multielement crystals is limited by segregation or stoichiometry deviation during the thermal drawing and recrystallization process. This paper presents a new method, several times recrystallization by laser, to solve the crystal segregation problem of binary or multielement crystal core multimaterial fibers. [ABSTRACT FROM AUTHOR]

Engineering the optical bandgaps of classic ferroelectrics from the typical ultraviolet range down to the visible range is an emerging methodology of developing the next‐generation optoelectric and opto‐ferroelectric devices including ferroelectric solar cells, light‐driven transistors and modulators, and multi‐sensors/energy harvesters. Recently, a material interface comprised of a pseudo‐morphotropic phase boundary between the tungsten bronze and perovskite phases of the KNBNNO [(K,Na,Ba)x(Ni,Nb)yOz] has been reported to be an effective approach for bandgap engineering while retaining excellent ferroelectricity and piezoelectricity of the perovskite‐phased KNBNNO. However, this approach requires the compositions of the materials to be determined at the synthesis stage, leaving little room for any further modification of the microstructure and functional properties at the post‐processing stage. This paper presents a post‐processing method, that is, atmospheric annealing in N2 and O2, to grow the necessary tungsten bronze phase out of the perovskite phase in the KNBNNO. This method is advantageous over the previously reported because it enables to grow the tungsten bronze–perovskite interface region independent of the initial composition. The distinctive electrical properties and the giant tunability of photoconductivity of the tungsten bronze phase, the perovskite phase, and the interface are characterized in detail in this paper, supporting the exploitation of fabricating opto‐ferroelectric devices using the reported method which is compatible and comparable with some of the post‐processing methods applied in the silicon industry. [ABSTRACT FROM AUTHOR]

In this paper, X‐ray‐activated super long persistent ultraviolet A luminescence from Ca3(PO4)2: Ce3+ has been observed. The crystal structure analysis has shown that the as‐prepared samples are pure β‐Ca3(PO4)2 phases with rhombohedral structure and R3c space group. The photoluminescent spectra of the samples all consist of a broad band in 340–400 nm UVA1 region, which is assigned to the 5d1–4f1 electronic transition of Ce3+ ions. More important, under the 3 min X‐ray irradiation, Ca3(PO4)2: Ce3+ show super long persistent luminescence in the UVA1 region, which can persist for more than 16 h. And its afterglow intensity after 16 h decay is still 4.10 times stronger of the back ground intensity. Furthermore, only 10 s X‐ray irradiation can induce excellent long persistent UVA luminescence of Ca3(PO4)2: 0.08Ce3+, which can persist for more than 5 h and afterglow emission intensity is about 3.03 times of the background intensity. The trap analysis has confirmed that the different X‐ray irradiation time do not create new traps and there is the same trap with 0.75 eV trap depth existing even under the extremely low X‐ray dose (10 s X‐ray irradiation). Furthermore, under 10 s X‐ray irradiation, the thermoluminescence (TL) intensity of Ca3(PO4)2: 0.08Ce3+ still reaches 0.32 times of the initial TL intensity even after 120 min, which thus leads to the super long persistent luminescence. Thus, the large amounts of trapped electrons induced by the high energy X‐ray irradiation are the principal cause for super long persistent UVA luminescence of Ca3(PO4)2: Ce3+. [ABSTRACT FROM AUTHOR]

As a luminescent center ion in materials for deep red and near‐infrared light, Cr3+ has been extensively studied in octahedral host materials. In this study, using zinc aluminate (ZnAl2O4) and magnesium aluminate (MgAl2O4) spinels with abundant octahedra as substrates, a series of Zn1−xMgxAl2O4:0.5%Cr3+ (x = 0, 0.2, 0.4, 0.6, 0.8, and 1) fluorescent powders were first prepared via a high‐temperature solid‐state method. The influence of different Mg/Zn ratios on (Zn/Mg)Al2O4:0.5%Cr3+ optical properties was thoroughly explored. Experimental results show that an increase in the Mg/Zn ratio reduces the crystal field strength (Dq) and leads to distortion of the [AlO6] octahedra, resulting in broadening of the photoluminescence emission spectrum. Furthermore, the addition of Mg gradually reduces the formation of inverse spinel. An appropriate Mg/Zn ratio can improve luminescent intensity and quantum efficiency. In summary, this paper, through bandgap engineering by adjusting the Mg/Zn ratio, provides a detailed account of the changes in optical properties and the underlying mechanisms during the transition from ZnAl2O4:0.5%Cr3+ to MgAl2O4:0.5%Cr3+ spinels. It offers valuable insights for further research on the practical applications of Cr3+ in areas such as lighting displays and bioimaging. [ABSTRACT FROM AUTHOR]

With the emergence of 5G–6G communication technology, the miniaturization and integration of electronic components are crucial. Ba3Ti4Nb4O21 (BTN) ceramics with hexagonal structures have attracted special attention due to their high dielectric constant, which shows greater application potential in communication base stations and dielectric resonators. However, its high sintering temperature and low‐quality factors also greatly limit the application field. In this paper, boric acid (H3BO3) as a dopant, was used to investigate the influence on the structure, microstructure, Raman spectrum, and microwave properties for Ba2.92Cu0.08(Zn1/3Nb2/3)2Ti2Nb4O21 (BCZTN)‐xHB (0.25≤x≤1.25 wt%) ceramics. The results reflected that H3BO3 was an effective additive, which could promote ceramic densification, accelerate grain growth and uniform distribution, and enhance its microwave performance. Among them, high densification was 93.92 ± 0.35%, and the Q × f value ∼16981 ± 340 GHz at x = 0.75, was more than 2∼3 times higher than other BTN‐based ceramics. Superior microwave dielectric properties were achieved for 0.75 wt% H3BO3‐doped BCZTN ceramic sintered at 900°C: εr∼42.35 ± 0.48, Q×f∼16981 ± 340 GHz, and τf∼40.02 ± 1.43 ppm/°C. More encouragingly, BCZTN‐0.75HB ceramic did not chemically react with Ag, which suggested that it had the potential to be a candidate material for low‐temperature co‐fired ceramics base station communication devices. [ABSTRACT FROM AUTHOR]

In this paper, X‐ray‐activated super long persistent ultraviolet A luminescence from Ca3(PO4)2: Ce3+ has been observed. The crystal structure analysis has shown that the as‐prepared samples are pure β‐Ca3(PO4)2 phases with rhombohedral structure and R3c space group. The photoluminescent spectra of the samples all consist of a broad band in 340–400 nm UVA1 region, which is assigned to the 5d1–4f1 electronic transition of Ce3+ ions. More important, under the 3 min X‐ray irradiation, Ca3(PO4)2: Ce3+ show super long persistent luminescence in the UVA1 region, which can persist for more than 16 h. And its afterglow intensity after 16 h decay is still 4.10 times stronger of the back ground intensity. Furthermore, only 10 s X‐ray irradiation can induce excellent long persistent UVA luminescence of Ca3(PO4)2: 0.08Ce3+, which can persist for more than 5 h and afterglow emission intensity is about 3.03 times of the background intensity. The trap analysis has confirmed that the different X‐ray irradiation time do not create new traps and there is the same trap with 0.75 eV trap depth existing even under the extremely low X‐ray dose (10 s X‐ray irradiation). Furthermore, under 10 s X‐ray irradiation, the thermoluminescence (TL) intensity of Ca3(PO4)2: 0.08Ce3+ still reaches 0.32 times of the initial TL intensity even after 120 min, which thus leads to the super long persistent luminescence. Thus, the large amounts of trapped electrons induced by the high energy X‐ray irradiation are the principal cause for super long persistent UVA luminescence of Ca3(PO4)2: Ce3+. [ABSTRACT FROM AUTHOR]

In this paper, we examine the cleavage fracture anisotropy in tantalum carbides, namely, TaC, α‐Ta2C, and ζ‐Ta4C3 − x, using density functional theory (DFT) calculations. Our investigation identifies the presence of multiple low‐energy cleavage planes indicating multiple potential pathways for crack propagation in these ceramics, even the low symmetry compounds. The anisotropy characteristics of cleavage fractures exhibited by α‐Ta2C and ζ‐Ta4C3 − x closely align with the intrinsic fracture anisotropy observed in TaC. Notably, there exist at least three pyramidal planes in ζ‐Ta4C3 − x whose cleavage energies are less than those of the carbon‐depleted basal planes, previously reported to have the lowest cleavage energy. The observed preference in experiments for cleavage along carbon‐depleted basal planes, exclusive of other identified low‐energy planes, points to factors beyond cleavage energy influencing cleavage plane preference. [ABSTRACT FROM AUTHOR]

The penetration of copper‐smelting slag into refractories is a major challenge to the research of chromium‐free refractories for copper‐smelting furnace. In this paper, Y2O3 was added to regulate the pore structure of periclase refractories, which enhanced their various properties, especially corrosion resistance to copper converter slag. The results showed that the periclase refractories doped with 1.0 wt.% Y2O3 (1Y sample) possessed the optimum properties. Compared to the sample without Y2O3, the apparent porosity of 1Y sample was decreased by 7.3%, and its average pore diameter was only 3.7 μm. The addition of Y2O3 filled the pores among MgO grains and promoted the expansion of high melting point silicates, thereby reducing the pore size and causing more complex pore structures. This was beneficial to improving the corrosion resistance of periclase to copper slag, especially to prevent the penetration of Cux+ and Na+. After static slag corrosion, the permeability index was significantly decreased by 41% compared to periclase refractories without Y2O3. Moreover, compared to industrial MgO–Cr2O3 refractories, the 1Y sample possessed better resistance to copper slag erosion based on rotating finger tests, and its permeability index and penetration depth decreased by almost 50%. [ABSTRACT FROM AUTHOR]

So far, developed microwave absorbers exhibit significant changes in absorption with temperature, which hinder their operation within a wide temperature range. In this paper, a microwave absorber based on SiBCN ceramics was prepared. Due to the excellent high‐temperature stability of SiBCN ceramics, its permittivity changes less with temperature, avoiding the issue of performance deterioration or even failure that traditional refractory absorbers face at high temperatures. The experiment proves the absorption bandwidth for –15 dB of the SiBCN metamaterials absorber (SMA) is 12 GHz at 800°C, with a maximum absorptivity of 99.99%. According to the computed data, the resonance loss contributes 81.9 to 94.5% of the microwave absorption of SMA. This work demonstrates significant potential for applications in radar stealth under harsh conditions. [ABSTRACT FROM AUTHOR]

Functionally graded ceramics (FGCs), which combine the properties of various composite ceramics, have been widely used in the aerospace, armament, and other industries. One of the newest melt‐growth ceramic additive manufacturing techniques, laser directed energy deposition (LDED), enables the creation of gradient materials by controlling the ratio of powder delivery. Ceramic–ceramic type gradient materials are the subject of fewer studies, and the majority of LDED gradient material systems now in research are metal–metal type and metal–ceramic type gradient materials. In this paper, LDED is used to create TiCp reinforced Al2O3 FGCs with three different transition paths. The results indicate that the longitudinal section of the gradient samples distinctly exhibits characteristics of gradient distribution. Furthermore, as the proportion of TiCp increases, there is a corresponding increase in the proportion of TiCp particles in the samples. The microstructure of Al2O3 transforms from columnar crystals to irregular shapes. Regarding the mechanical properties of the gradient samples, the area containing 30 wt.% of TiCp shows a significant improvement in wear resistance, with a 48.13% increase compared to the Al2O3 region. Additionally, this region demonstrates a 12.62% rise in hardness and a 9.48% increase in fracture toughness. [ABSTRACT FROM AUTHOR]

Recently, there has been a growing demand for broadband near‐infrared (NIR) phosphor. The paper proposes a novel Cr3+ doped Ca2Y3Sb3O14 phosphor through basic research of Ca2Ln3Sb3O14: Cr3+ (Ln = Sc, Lu, and Y) phosphor. Under 467 nm excitation, Ca2Y3Sb3O14: Cr3+ phosphor shows a broad NIR emission band (650–950 nm) centered at 776 nm with a full width at half‐maximum of 110 nm. The optimal Cr3+ doping concentration is 0.05, with an internal quantum efficiency of 78%. Meanwhile, the photoluminescence emission intensity at 373 K remains 61.3% of that at room temperature. Using phosphor‐in‐glass technology, a glass–ceramic plate showed a slight improvement in its thermal stability compared to the pure phosphor. Combining Ca2Y3Sb3O14: 0.05Cr3+ phosphor with a commercial blue‐light‐emitting chip presents an output power of 44.51 mW with a photoelectric conversion efficiency of 14.78% at a drive current of 100 mA. These results suggest that the Ca2Y3Sb3O14: Cr3+ phosphor has great potential in the pc‐light‐emitting diodes. [ABSTRACT FROM AUTHOR]

Dielectric capacitors have been widely studied in advanced electronics systems due to their rapid discharge rate and high-power density. Among them, relaxor ferroelectrics characterized by nanodomains possess broad application prospects as dielectricmaterialswith high energy density and high efficiency. In this paper, the dielectric characteristics, energy storage performance, and charge--discharge behavior of rare-earth Yb-doped Sr0.7Bi0.2TiO3 ceramics are systematically investigated. The Yb-doped SBT ceramics reduced the grain size, improved the insulation and thermal conductivity, and significantly improved the dielectric breakdown strength. Finally, a high recoverable energy density of 2.32 J/cm³ and an excellent energy storage efficiency of 92.2% were obtained at 300 kV/cm. In addition, pulsed charge--discharge tests show that Sr0.7Bi0.15Yb0.05TiO3 possesses a rapid discharge rate and high-power density with superior thermal stability. Based on these outstanding characteristics, Sr0.7Bi0.15Yb0.05TiO3 exhibits promising applications in pulsed power systems. [ABSTRACT FROM AUTHOR]

The brittleness of Si3N4 ceramics has always limited its wide application. In this paper, Si3N4 ceramics were prepared based on foam. Combining the unique honeycomb structure of the ceramic foams and the self‐toughening mechanism of Si3N4, the strengthening and toughening of Si3N4 ceramics can be further achieved by adjusting the microstructure of Si3N4 ceramic foams. The powder particles are self‐assembled by particle‐stabilized foaming to form a foam body with a honeycomb structure. It was pretreated at different temperatures (1450–1750°C). The microstructure evolution of foamed ceramics at different pretreatment temperatures and the conversion rate of α‐Si3N4 to β‐Si3N4 at different pretreatment temperatures were explored. Then the foamed ceramics with different microstructures are hot‐press sintered to prepare Si3N4 dense ceramics. The effects of different microstructures of foamed ceramics on the strength and toughness of Si3N4 ceramics were analyzed. The experimental results show that the relative density of Si3N4 ceramics prepared at a particle pretreatment temperature of 1500°C is 97.8%, and its flexural strength and fracture toughness are relatively the highest, which are 1089 ± 60 MPa and 12.9 ± 1.3 MPa m1/2, respectively. Compared with the traditional powder hot‐pressing sintering, the improvement is 21% and 33%, respectively. It is shown that this method of preparing Si3N4 ceramics based on foam has the potential to strengthen and toughen Si3N4 ceramics. [ABSTRACT FROM AUTHOR]

Oxidation of SiC plays a critical role in the durability of ceramic matrix composites, as large changes in molar volume generate significant stresses that can drive cracking in adjacent features. The analysis of such phenomena requires coupling between descriptions of diffusion through the oxide, growth of the oxide domain (i.e., evolution of the oxide/SiC interface), and creep relaxation in the oxide at elevated temperatures. This paper presents a two‐dimensional finite element framework that uses a single finite element mesh to predict these behaviors; large changes in the oxide geometry are simulated by tracking the oxidation front as a discrete interface and periodically re‐meshing. The numerical performance of the framework is illustrated using an analytical description of oxidation of a flat surface and subsequent stress evolution. The framework is then used to analyze internal oxidation within a cylindrical cavity for a wide range of temperatures and water vapor concentrations pertinent to gas turbines. The results are used to discuss the roles of oxide growth rate, creep, and geometry with respect to the tensile stresses that develop in the adjacent SiC, and their implications for oxidation‐driven damage at high temperatures. [ABSTRACT FROM AUTHOR]

Ettringite‐accelerated binders composed of CAC–PC–C$ (calcium aluminate cement–Portland cement–calcium sulfate) and CSA–PC–C$ (calcium sulfoaluminate cement–Portland cement–calcium sulfate) have been used widely for indoor applications, such as self‐leveling floor screeds, underlayment, and tile adhesives owing to their rapid setting, early strength gain, and shrinkage compensation properties. These properties also make these binders appealing candidates for outdoor rapid repair (e.g., highways, bridge decks, and airfield pavements). However, a central question remains: Does ettringite remain stable in outdoor exposure conditions? If so, which factors will contribute positively/negatively to the long‐term stability of ettringite in these systems? To address these questions, this critical review presents the current state of knowledge regarding the hydration of ternary binders composed of CAC–PC–C$ and CSA–PC–C$ with respect to ettringite formation and the factors affecting the stability of ettringite thereafter. The purpose of this review paper is to synthesize and analyze current research regarding conditions that promote or deter ettringite stability, establish what information is missing, unclear, or contradictory, and identify remaining research needs to address the identified knowledge gaps. [ABSTRACT FROM AUTHOR]

In this paper, we report the synthesis of fully dense and ultrafine‐grained binderless tungsten carbide (WC) by novel dynamic sinter forging. A nearly fully dense sample was obtained at 1500°C and 220 ± 30 MPa@90 min. The hardness and fracture toughness of the sample with forging time of 180 min are 29.6 GPa and 7.3 MPa·m1/2, respectively, much higher than the counterparts prepared by conventional sinter forging and other techniques. The enhanced densification and mechanical properties are attributed to the intragranular plastic deformation accommodated grain‐boundary sliding induced by oscillatory pressure during dynamic sinter forging. The current results suggest a promising approach for the manufacturing of high‐performance binderless WCs. Also, the method is likely applicable to other material systems. [ABSTRACT FROM AUTHOR]

The effects of irradiation‐induced defects on the fluorite‐structured dioxide materials were investigated in the literature and explained with complex physical phenomena. An interpretation that can simply explain their effects on the structure has not been put forward so far. However, in a recent atomistic simulation study, a specific defect was found to be directly responsible for the α‐particle irradiated UO2 lattice dilatation, and there was a linear relationship between them. It was also determined that this linear equation has two different slopes at low and high defect concentrations. In this paper, it was found that these phenomenon were not specific to UO2 and applicable to all fluorite‐structured actinide and lanthanide dioxides studied here (CmO2, AmO2, CeO2, UO2, NpO2, PuO2, ThO2). The findings provide clues to the existence of more general law. The results have the potential to lead to significant improvements, such as why different radiation types (α‐particle, α‐decay, fission) swell the lattice at different saturation levels. [ABSTRACT FROM AUTHOR]

The origin of the excellent properties of KTN‐based materials around Curie temperature (TC), which should be originated form the motion of polar nanoregions (PNRs), has attracted considerable research interest. In this paper, the relaxation of a KTa0.63Nb0.37O3 single crystal is discussed with the temperature dependence of permittivity. Moreover, its pyroelectric effect above TC is investigated. In detail, the pyroelectric coefficient decreases from ∼110.0 to ∼13.0 μC/(m2 K), with the temperature increasing from 22 to 33°C, and finally reduces to 0 at 100°C with PNRs disappear. Moreover, the dynamic dielectric nonlinearity for the KTN single crystal is studied in the paraelectric phase. To investigate these mechanisms, the amplitude and phase angle of the first and third harmonics under various electric fields, frequencies, and temperatures are analyzed. As a result, the motions of PNRs induced by electric field, which is pinned and depinned by the defect, are presented to explain the nonlinear dielectric response observed in the paraelectric KTN single crystal. [ABSTRACT FROM AUTHOR]

Silica glass is a superior functional material due to its excellent thermophysical properties. With the increasing demand for large‐size and high‐purity silica glass, a novel chemical vapor deposition (CVD) furnace characterized by a crucible has been proposed, which requires a deep understanding of heat and mass transport characteristics inside for better control. Aimed at this, a comprehensive simulation model is developed in the paper. The model is well verified with the experimentally measured temperature and is then used to examine distributions of temperature and critical components in the furnace. Effects of the injection conditions are further investigated, among which the H2–O2 equivalence ratio and flow rate have a great influence on the temperature and components distributions, whereas the SiCl4 flow rate mainly affects the SiO2 distribution. An improved injection condition is put forward finally, which is much better than the reference case; the average for the temperature and SiO2 concentration on the deposition surface is increased, respectively, by 23 K and 0.018 mol/m3, and sufficient homogeneity is maintained. [ABSTRACT FROM AUTHOR]

Silicon carbide (SiC) fiber‐reinforced SiC matrix (SiC/SiC) composites have emerged as a new material candidate for fuel claddings in light water reactors. Recent studies showed that the load capacity of SiC/SiC materials exhibits a considerable statistical variation. Therefore, reliability analysis plays a critical role in design of SiC/SiC composite claddings. This paper presents a probabilistic model for the lifetime distribution of SiC/SiC composites. The model is anchored by a multiaxial stress‐based failure criterion and subcritical damage accumulation mechanism. Based on the kinetics of subcritical damage growth, the lifetime distribution of a laboratory test specimen for any given loading history can be calculated. A finite weakest‐link model is used to extrapolate the lifetime distribution of test specimens to full‐length claddings. It is shown that the damage accumulation mechanism has a strong influence on the lifetime distribution of the cladding. This finding highlights the importance of understanding the static fatigue behavior of SiC/SiC composites. The present analysis also demonstrates an intricate length effect on the failure probability of the cladding, which is expected to play a crucial role in design extrapolation. [ABSTRACT FROM AUTHOR]