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We perform dielectric and impedance spectrums on the compressively-strained ceramics of multiferroic bismuth ferrite. The subsurface-nanolayer quasipolarons manifest the step-like characteristic of pressure-dependent transient frequency and, furthermore, pressure-dependency fails in the transformation between complex permittivity and electrical impedance, which is well-known in classic dielectric physics, as well as the bulk dipole chain at the end of the dissipation peak. [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]

Hydrogen peroxide (H2O2) plays a pivotal role in multiple industries, spanning healthcare, energy, chemical synthesis, and environmental protection, yet achieving its safe, ecofriendly, simple, and efficient production under ambient conditions remains challenging. In contrast to traditional piezoelectric and photocatalysis techniques, tribocatalysis has recently attracted attention owing to its mild requirements and low energy consumption. Thus, in this study, we synthesized BaxSr1–xNb2O6 (x = 0.4, 0.5, 0.6, 0.7) (BSN) ferroelectric nanopowders via solid-phase synthesis and high-energy ball milling to investigate the impact of BSN tribocatalysis on H2O2 production. Our findings reveal that H2O2 can be efficiently synthesized through a tribocatalysis pathway at room temperature and normal pressure by exerting mechanical force during physical contact between BSN particles and deionized water/O2 interfaces. This interaction induces electron transfer, leading to the generation of reactive free radicals (•OH and •O2–). Subsequently, these free radicals combine to form H2O2 (2•OH → H2O2, •O2– + e– + 2H+ → 2H2O2). Our results demonstrate that strong ferroelectric properties can enhance the catalytic capability for H2O2 production. Furthermore, the efficiency can be significantly enhanced by facilitating the passage of O2 and incorporating a sacrificial agent, resulting in a high production rate up to 952.65 μmol L–1 h–1. This study presents a new and efficient method for preparing hydrogen peroxide. [ABSTRACT FROM AUTHOR]

Bi2VO5.5‐based materials are well‐known oxide ion conductors owing to their exceptionally high ionic conductivity. However, their poor phase and redox stabilities under a reducing atmosphere hinder their practical application as electrolytes for solid oxide fuel cells. Here, a series of novel quadruple metal‐doped bismuth vanadium system materials Bi2V1−4x(CuNiNbTi)xO5.5−δ (0 ≤ x ≤ 0.1) are prepared through a traditional solid state reaction method, aiming to enhance the phase and redox stability under reducing atmosphere. The results reveal that multiple‐metal‐doping can stabilize the tetragonal phase of Bi2VO5.5 to room temperature and show good phase and structural stabilities under inert or high oxygen partial pressure atmospheres, as well as pure oxide ion conduction which is slightly lower than that of the parent material. However, under a reducing environment, the Bi2V1−4x(CuNiNbTi)xO5.5−δ materials would still undergo a phase decomposition, yielding elemental bismuth impurity, and introducing strong electronic conduction. Thus, how to improve the phase and redox stabilities under the reducing atmosphere of the Bi2VO5.5‐based materials is still the endeavor direction in the future. [ABSTRACT FROM AUTHOR]

In many studies, the properties of BiFeO3–BaTiO3 (BF–BT) ceramics vary greatly using different raw reagents, which makes it challenging to obtain reliable and repeatable properties of BF–BT‐based devices. In this work, 0.7BiFeO3–0.3BaTiO3 (0.7BF–0.3BT) ceramics were fabricated by a conventional solid‐phase synthesis using TiO2 reagents with varied purities of 98%, 99%, 99.9%, and 99.99%, respectively. The phase structure, microstructure, ferroelectric, and piezoelectric properties were comprehensively studied. All compositions of the ceramics exhibit a pseudo‐cubic phase perovskite structure, and the fraction of the rhombohedral phase increases with increasing the TiO2 purity. Additionally, backscattered electron images and energy‐dispersive spectroscopy revealed an obvious core–shell structure within grains. In particular, the 0.7BF–0.3BT ceramics prepared with 98% purity TiO2 exhibited superior ferroelectric and piezoelectric properties, d33 ∼ 220 pC/N and d33∗$d_{{\mathrm{33}}}^{\;*}$ ∼ 230 pm/V. The ceramics prepared with higher purity TiO2 suffered from severe leakage conduction, which can be well addressed by adding excess TiO2. Our work reveals the importance of different grades of purity TiO2 on the electrical properties of BF–BT ceramics. [ABSTRACT FROM AUTHOR]

Electronic components are widely used in the field of electronic information. It is more and more important to prepare miniaturized and better performance electronic components. In this work, Sr1−3x/2YxTiO3 (x = 0.005, 0.0075, 0.01, 0.0125) ceramics were prepared by the traditional solid‐phase synthesis method. N2 annealing induces the appearance of lattice defects and free carriers (VO..,e′,Ti3+)$(V_{\mathrm{O}}^{..},\,{\mathrm{e^{\prime}}},\,{\mathrm{T}}{{\mathrm{i}}^{3 + }})$ and defect dipoles (YṠr−VSr′′,Ti3+−Vo..−Ti3+${{\mathrm{Y}}_{{\mathrm{\dot Sr}}}} - {V^{\prime\prime}_{{\mathrm{Sr}}}},{\mathrm{T}}{{\mathrm{i}}^{3 + }} - V_{\mathrm{o}}^{..} - {\mathrm{T}}{{\mathrm{i}}^{3 + }}$). The defect dipoles easily induce the electron‐pinning defect dipole effect and inhibit the movement of free carriers, which can enhance the dielectric constant and reduce the dielectric loss simultaneously. The electrons cannot pass through the insulating grain boundary and accumulate in the conductive grains under an external electric field, forming the internal barrier layer capacitance (IBLC). The ceramic was further refined by high‐energy ball milling to improve the temperature and frequency stability of the ceramic. Under the combined action of rare‐earth doping, atmosphere annealing, and high‐energy ball milling, a dielectric ceramic material with colossal permittivity, low loss, high resistivity, frequency, and temperature stability that meets the ELA X9R capacitor standard was prepared. [ABSTRACT FROM AUTHOR]

The 0.55Bi(Mg1/2Ti1/2)O3–0.45PbTiO3 ceramics exhibit notable dielectric anomalies across three temperature ranges. The low‐temperature anomaly is attributed to a reentrant dipole glass‐like relaxor behavior; the mid‐temperature anomaly results from a ferro‐paraelectric phase transition; and the high‐temperature anomaly is associated with a diffuse phase transition. The system demonstrates favorable piezoelectric, electromechanical, and ferroelectric properties. Specifically, the ceramic presents a piezoelectric coefficient (d33) of 220 pC/N, an electromechanical coupling factor (kp) of 27%, and a remanant polarization (Pr) of 32.5 μC/cm2. Moreover, it maintains an operational capability up to 643 K. The unsaturated P(E) loops are formed through the coupling polarization between polar nanoregions (PNRs) and P4mm ferroelectric domains. By examining the electrical modulus, the dynamic PNRs resulting from ferroelectric phonon localization and the formation of P4mm ferroelectric domains were analyzed. The result reveals a mesoscale coupling relationship between the origin of high‐temperature piezoelectric stability and the dynamics of PNRs, thereby providing noble insights into the (1 − x)BiMeO3–xPbTiO3 system. [ABSTRACT FROM AUTHOR]

Revealing the local structure information of relaxor ferroelectrics is necessary for a clear understanding of their structure–property relationships, especially the determination of the size of polar nanoregions (PNRs), which is still a long-standing challenge. In this work, the local structure of the pseudo-cubic solid solutions 0.60Bi(Mg1/2Ti1/2)O3–0.40PbTiO3 and 0.65Bi(Mg1/2Ti1/2)O3–0.35PbTiO3, which exhibit re-entrant relaxor behavior, has been determined using the statistical model and reverse Monte Carlo (RMC) modelling of total scattering data. The pair distribution function revealed significant deviation between the local and long-range structures with each of the cations exhibiting unique polyhedral configurations, which required the use of a phase coexistence model to characterize the local structure. The lone-pair bearing Bi and Pb cations exhibited the greatest amount of displacement and disordering. An effective method was proposed to determine the size and orientation of PNRs (∼2 nm) based on the correlation angle between displaced A-site pairs. The size of these regions below freezing temperature is in agreement with the result of the statistical model. This method is suitable for relaxor systems, which lack long-range ferroelectric order, providing an excellent characterization of PNRs and an understanding of the physical properties of relaxor ferroelectrics. [ABSTRACT FROM AUTHOR]

Photocatalytic conversion of CO2 into renewable fuels is an exciting and challenging approach to mitigate carbon emissions and the energy crisis. The efficiency is hindered by the insufficient carrier transport capacity and high electron–hole pair complexation of the catalysts. The inherent spontaneous polarization in ferroelectric materials can affect the generation, transportation, and isolation of intermediates within catalytic reactions in modulating the pace and effectiveness of photocatalytic processes. Herein, ferroelectric bismuth sodium titanate (BNT) decorated with oxygen vacancies (OVs) via in situ reduction is first explored to promote the photocatalytic CO2 reduction reaction (CO2RR). The chemical states and coordination environment of the cations and OVs are elaborated by using the X-ray absorption fine structure to probe weakened Bi–O bonds and enhanced lattice distortion. Besides built-in electric fields originating from intrinsic spontaneous polarization, carrier dynamics and reactive sites are optimized with extended visible light absorption thanks to the special morphology and OVs. Remarkably, oxygen defected catalysts show 18 times higher CO reduction yield than pristine BNT, outperforming state-of-the-art bulk ferroelectrics for photocatalytic CO2RR. Interestingly, the product selectivity can be tailored after a poling treatment. This work provides a systematic approach for designing efficient ferroelectric photocatalysts, and meanwhile, expands the ferroelectric photocatalyst family for advancing CO2 conversion. [ABSTRACT FROM AUTHOR]

Series of Ca2+ ion‐doped high‐entropy [(La0.25Nd0.25Sm0.25Eu0.25)1−xCax]2Zr2O7−δ (x = 0.025, 0.05, 0.075, 0.1, and 0.2) materials are prepared through a traditional solid‐state reaction method. The solubility of Ca is revealed to be x = 0.075, which is higher than that in the cases with single lanthanide on the A‐site of A2Zr2O7‐based pyrochlore materials. The study of electrical properties discloses that the conductivities of [(La0.25Nd0.25Sm0.25Eu0.25)1−xCax]2Zr2O7−δ increased with Ca‐doping level and dominated by oxide ion conduction, without noticeable proton conduction. Good chemical stability is revealed for these materials under a wet CO2 atmosphere. [ABSTRACT FROM AUTHOR]

Bi2VO5.5‐based materials are well‐known oxide ion conductors owing to their exceptionally high ionic conductivity. However, their poor phase and redox stabilities under a reducing atmosphere hinder their practical application as electrolytes for solid oxide fuel cells. Here, a series of novel quadruple metal‐doped bismuth vanadium system materials Bi2V1−4x(CuNiNbTi)xO5.5−δ (0 ≤ x ≤ 0.1) are prepared through a traditional solid state reaction method, aiming to enhance the phase and redox stability under reducing atmosphere. The results reveal that multiple‐metal‐doping can stabilize the tetragonal phase of Bi2VO5.5 to room temperature and show good phase and structural stabilities under inert or high oxygen partial pressure atmospheres, as well as pure oxide ion conduction which is slightly lower than that of the parent material. However, under a reducing environment, the Bi2V1−4x(CuNiNbTi)xO5.5−δ materials would still undergo a phase decomposition, yielding elemental bismuth impurity, and introducing strong electronic conduction. Thus, how to improve the phase and redox stabilities under the reducing atmosphere of the Bi2VO5.5‐based materials is still the endeavor direction in the future. [ABSTRACT FROM AUTHOR]

In recent years, catalytic degradation driven by mechanical‐energy tribocatalysis has gained much attention. Point defects play very important on the catalytic activity of ferroelectric oxides. In this study, we focus on the influence of oxygen vacancies on the catalyst performance of ferroelectric oxide KSr2Nb4TaO15 (KSNT) with a tetragonal tungsten bronze structure. The concentration of oxygen vacancies is modified by sintering atmosphere. The KSNT sintered in N2 atmosphere exhibits the best tribocatalytic degradation efficiency of 96.7% within 2 h for degradation rhodamine B due to high concentration of oxygen vacancies. The excellent degradation efficiency is attributed to the defect energy level of KSNT and high electron–hole separation efficiency. This work reveals the relationship between oxygen vacancies and tribocatalysis efficiency, which is helpful to design and modify the new ferroelectric oxides for tribocatalysis. [ABSTRACT FROM AUTHOR]