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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]

TeO2 single crystal has drawn much attention in recent years due to its excellent acousto‐optic (AO) performance in the field of spectral imaging and optical processing. The optical properties of TeO2 single crystal are critical for the fabrication of AO devices. To improve the optical properties of the TeO2 single crystal, Mn4+ ions were doped into the TeO2 lattice. Herein, bulk TeO2 single crystal and TeO2:0.02Mn4+ single crystal have been successfully grown by a Bridgman method. Compared with the TeO2 single crystal, a 30% transmittance increase was observed in the TeO2:0.02Mn4+ single crystal. Furthermore, the TeO2:0.02Mn4+ single crystal shows a smaller extinction coefficient (≤0.01) in the Vis–NIR region, indicating less optical loss. The bandgap energy of TeO2:0.02Mn4+ was broadened from 3.360 to 3.635 eV. In addition, TeO2:0.02Mn4+ single crystal exhibits a higher refractive index (about 2.244), which indicates that TeO2:0.02Mn4+ single crystal is a potential medium for high‐efficiency AO devices. [ABSTRACT FROM AUTHOR]

Local electric field distribution in the dielectric layer of BaTiO3‐based multilayer ceramic capacitors (MLCCs) is investigated by Kelvin probe force microscopy before and after highly accelerated life test (HALT) degradation combined with the energy band diagram. An unusual electric field concentration phenomenon is directly visualized near the HALT cathode region in the degraded MLCCs while a reverse voltage is applied. Such abnormal behavior is ascribed to the migration of oxygen vacancies within the dielectric layer during the HALT, leading to the formation of a P‐N junction structure and further a heightened barrier under a reverse bias. As a result, a P‐N junctional model is proposed for understanding local failure mechanism of the degraded MLCCs, which enrich the insights into the insulation resistance degradation and the reliability of MLCCs. [ABSTRACT FROM AUTHOR]

Scanning thermal microscopy is used to perform direct imaging local conductive path and dynamic behaviors in the degraded multilayer ceramic capacitors (MLCCs) due to the thermal conductivity difference between the dielectric layers and the conductive regions. For local conductive path, its electrical tree dynamic growth behaviors under the dc bias on and off state are clearly obtained in the thermal image. Such phenomena reveal that space–charge‐limited current mechanism dominates in local conductive path region of MLCCs. The results give a strong demonstration of scanning thermal microscopy as a powerful tool for imaging local conductive behavior in MLCCs, which provides us a direct, unique view to clarify local breakdown mechanism and enriches our insights in the insulation resistance degradation and the reliability of MLCCs. [ABSTRACT FROM AUTHOR]

Herein, the obtained Cu0.5Co0.5‐ZIF@Fe2O3@CC‐150 heterojunction (termed as Cu1‐xCox‐ZFC‐150) showed high hydrogen and oxygen evolution reaction (HER and OER) activities with low overpotential small Tafel slope. When employed to be the bifunctional anode and cathode, they only needed a cell voltage of 1.62 V. The composite also exhibited excellent photocatalytic performance on CO2 evolution into CO and CH4. The enhanced OER kinetics and Z‐scheme charge transfer model for photocatalytic property have been discussed based on the experiments and density functional theory (DFT) analysis. The optimized phase interfaces, abundant active sites, optional oxygen vacancy, and adjusted Gibbs free energy were beneficial for the fast electron/ion transport enhancing the water splitting performance. [ABSTRACT FROM AUTHOR]

SrTiO3‐modified lead‐free piezoelectric ceramics, (0.93‐x)Bi0.5Na0.5TiO3‐xSrTiO3‐0.06BaTiO3‐0.01 K0.5Na0.5NbO3 [(BNT‐xST)‐BT‐KNN, x = 0‐0.06], were prepared using a conventional solid‐state reaction method. The XRD structure analysis and electric properties characteristics revealed the ST‐induced phase transformation from the ferroelectric phase to the relaxor phase and their coexistence state. Benefiting from the ST‐destructed ferroelectric long‐range orders, the high normalized strain value of 600 pm/V was obtained in the (BNT‐0.02ST)‐BT‐KNN ceramic at 5 kV/mm. The ST‐generated relaxor phase was found to have a constructive effect on improving the temperature stability and restraining the hysteresis of the electric‐field‐induced strain. The normalized strain of (BNT‐0.06ST)‐BT‐KNN ceramics could be kept at a high value ~337 pm/V at elevated temperature up to 120°C. [ABSTRACT FROM AUTHOR]

2D tin selenide (SnSe) is a promising semiconductive material and its thermal stability is one of the most significant evaluating indicators. However, few works are involved in the temperature‐dependent structure stability of 2D SnSe nanosheets. Herein, local structure transformation of a 2D SnSe nanosheet into SnSe2 under high temperature is characterized by a novel atomic force microscope (AFM)‐based nanoscale thermomechanical method. Based on an AFM platform, the temperature‐dependent nanomechanical properties are investigated. A softness process is found to occur upon the surface of 2D SnSe, accompanying the structure transformation under high temperature. It means that the generation of SnSe2 is due to the structure collapse of SnSe, stemming from the evaporation of Sn atoms under about 90 °C. The transformation mechanism is further verified by a real‐time nanothermomechanical method. A deeper understanding of the thermal stability and thermal decomposition mechanism of 2D SnSe is promoted. The improved in situ nanomechanical method offers a highly sensitive method to probing the nanomechanical properties of 2D materials. [ABSTRACT FROM AUTHOR]

Room temperature semiconductor detector (RTSD) materials for γ‐ray and X‐ray radiation are in great demand for the nonproliferation of nuclear materials as well as for biomedical imaging applications. Halide perovskites have attracted great attention as emerging and promising RTSD materials. In this contribution, the material synthesis, purification, crystal growth, crystal structure, photoluminescence properties, ionizing radiation detection performance, and electronic structure of the inorganic halide perovskitoid compound TlPbI3 are reported on. This compound crystallizes in the ABX3 non‐perovskite crystal structure with a high density of d = 6.488 g·cm–3, has a wide bandgap of 2.25 eV, and melts congruently at a low temperature of 360 °C without phase transitions, which allows for facile growth of high quality crystals with few thermally‐activated defects. High‐quality TlPbI3 single crystals of centimeter‐size are grown using the vertical Bridgman method using purified raw materials. A high electrical resistivity of ≈1012 Ω·cm is readily obtainable, and detectors made of TlPbI3 single crystals are highly photoresponsive to Ag Kα X‐rays (22.4 keV), and detects 122 keV γ‐rays from 57Co radiation source. The electron mobility‐lifetime product µeτe was estimated at 1.8 × 10–5 cm2·V–1. A high relative static dielectric constant of 35.0 indicates strong capability in screening carrier scattering and charged defects in TlPbI3. [ABSTRACT FROM AUTHOR]

Ca and Ta co‐doped AgNbO3 antiferroelectric lead‐free ceramics were fabricated by rolling process technique, and improved energy storage properties were obtained. X‐ray diffraction and Raman spectra indicate a single perovskite structure for (Ag1‐2xCax)(Nb1‐xTax)O3 ceramics. The dielectric performances were also investigated, showing that increasing the content of Ca and Ta from 0.1 to 5 mol% gradually decreased the temperatures of the phase transition of monoclinic M1‐M2 and M2‐M3. This proved the enhanced antiferroelectricity stability associated with the enlarged low temperature phase transition region. The obtained (Ag0.90Ca0.05)(Nb0.95Ta0.05)O3 ceramics exhibit an enhanced recoverable energy storage density (3.36 J/cm3) and efficiency (58.3%) with good temperature and frequency stability. The same composition shows excellent charge and discharge properties with a discharge current as high as 91.5 A and fast discharge speed (150 ns discharge period). All these merits demonstrate that AgNbO3‐based antiferroelectric ceramics are competitive with other lead‐based and lead‐free dielectric capacitors, which are promising candidates for dielectric energy storage applications. [ABSTRACT FROM AUTHOR]

The thickness‐dependent nanoscale thermal behaviors of 2D SnSe nanosheets are studied via 3ω thermal mode atomic force microscopy and local Raman spectra. It is found that the 2D SnSe nanosheets demonstrate a decreasing thermal behavior with the reduction of thickness in the range of 6–40 nm. The unique thermal behavior is ascribed to the nonharmonic interlayer coupling along the armchair direction of SnSe crystal structure, in which the redshift of in‐plane vibration (Ag2, B3g) gives rise to phonon softening and finally the thickness‐dependent thermal behavior of SnSe nanosheets. Such nanoscale thermal behavior provides a new insight to understand the local thermal transport of 2D materials and their applications in energy consumption. [ABSTRACT FROM AUTHOR]

Three kinds of borosilicate glass‐ceramics Low temperature co‐fired ceramics (LTCC) substrate materials, Ca‐B‐Si‐O (CBS), Ca‐Al‐B‐Si‐O (CABS), and Ca‐Mg‐B‐Si‐O (CMBS), have been prepared, and the biocompatibility of these materials was evaluated. Compared with CBS and CMBS samples, the CABS sample presented the lowest crystallinity and dissolution in the bioleaching experiments. The direct and indirect cell culturing results showed that the CABS sample also possessed the best biocompatibility to the bone mesenchymal stem cells (BMSCs) due to its good bio‐stability and surface micro‐pore structure. The effects of surface topography and released ions on cytocompatibility were analyzed. These results were expected to offer some guideline information for developing LTCC substrate materials used in the microfluidic biosensors for the future biological and medical application. [ABSTRACT FROM AUTHOR]

The (Ba0.97− xCa0.03Dy x)(Ti0.98Mg0.02)O3 (BCTDM-nano) ( x = 0, 0.005, 0.01, 0.02, 0.03) ceramics with nanosized grains were synthesized through a solid-state reaction method. The influence of Dy3+ substitution on the lattice and electrical properties were investigated. The X-ray diffraction and Raman scattering analyses demonstrate that the Dy3+ ions could modulate the doping position of Ca2+ and Mg2+ and affect the tetragonality and defects in BaTiO3 matrix. The maximum dielectric constant was increased up to 2500 for the sample with x = 0.01. A high dielectric breakdown strength of 239 kV cm−1 was obtained at x = 0.01. The high grain boundary resistance resulted from a charge compensation by Dy doping benefits the improved dielectric breakdown strength. [ABSTRACT FROM AUTHOR]

The silver diffusion behavior in the low-temperature cofired ceramic (LTCC) comprising of borosilicate glass and alumina was investigated in this work. Transmission electron microscope (TEM) analysis revealed that silver ions diffused into LTCC materials through the glass phase. The addition of copper oxide in the LTCC materials can suppress the silver diffusion during the sintering process because of the enhanced crystallization of borosilicate glass, which leads to the quick increase in glass viscosity and retards the silver diffusion. Thermal dynamic analysis confirmed that the diffusion coefficient of silver in the copper-oxide-modified LTCC materials was largely reduced. [ABSTRACT FROM AUTHOR]

The heavy metal selenophosphate, Pb2P2Se6, is a promising new material for cost-effective X-ray/γ-ray detection. Crystal boules of Pb2P2Se6 up to 25 mm in length and 15 mm in diameter are grown by a vertical Bridgman method. They are cut and processed into size-appropriate wafers for physical, photo-transport property studies, as well as γ-ray detector testing. The material is a semiconductor with an indirect bandgap of 1.88 eV and has electrical resistivity in the range of 1 × 1010 Ω cm. Pb2P2Se6 single crystal samples display a significant photoconductivity response to optical, X-ray, and γ-ray radiation. When tested with a 57Co γ-ray source, Pb2P2Se6 crystals show spectroscopic response and several generated pulse height spectra resolving the 122.1 and 136.5 keV 57Co radiation. The mobility-lifetime product of Pb2P2Se6 is estimated to be ≈3.5 × 10−5 cm2 V−1 for electron carriers. The Pb2P2Se6 compound melts congruently at 812 °C and has robust chemical/physical properties that promise low cost bulk production and detector development. [ABSTRACT FROM AUTHOR]

The heavy metal selenophosphate, Pb2P2Se6, is a promising new material for cost-effective X-ray/γ-ray detection. Crystal boules of Pb2P2Se6 up to 25 mm in length and 15 mm in diameter are grown by a vertical Bridgman method. They are cut and processed into size-appropriate wafers for physical, photo-transport property studies, as well as γ-ray detector testing. The material is a semiconductor with an indirect bandgap of 1.88 eV and has electrical resistivity in the range of 1 × 1010 Ω cm. Pb2P2Se6 single crystal samples display a significant photoconductivity response to optical, X-ray, and γ-ray radiation. When tested with a 57Co γ-ray source, Pb2P2Se6 crystals show spectroscopic response and several generated pulse height spectra resolving the 122.1 and 136.5 keV 57Co radiation. The mobility-lifetime product of Pb2P2Se6 is estimated to be ≈3.5 × 10−5 cm2 V−1 for electron carriers. The Pb2P2Se6 compound melts congruently at 812 °C and has robust chemical/physical properties that promise low cost bulk production and detector development. [ABSTRACT FROM AUTHOR]

A compact diplexer is implemented in Low‐Temperature‐Cofired‐Ceramic (LTCC) technology and consists of six coupled substrate‐integrated‐waveguide (SIW) cavity resonators stacked in two layers. No transmission‐line based junction is used. The couplings between the cavities are achieved through both SIW irises and slots placed in metal layers. The diplexer has two third‐order filtering channels, centred at 2.7 and 3.3 GHz with 120 MHz bandwidths. The overall size of the diplexer is 27.74 mm (2.3λg at 3 GHz) × 10.4 mm (0.86λg at 3 GHz) × 0.84 mm, achieved by using an LTCC material of a high dielectric constant of 68. Simulations and measurements are in good agreement to demonstrate a compact diplexer based on an all‐resonator structure using high dielectric constant LTCC material. [ABSTRACT FROM AUTHOR]

Ferroelectric photovoltaic (FPV) effect has been studied among a series of non‐stoichiometric BaTiO3 (Ba/Ti = 0.92–1.05) ceramic chips prepared by tape casting method. The FPV performance increases abruptly when the Ba/Ti molar ratio deviates from the stoichiometry within 1%. Meanwhile, a photocurrent direction switching behavior is observed between Ti‐excess and Ba‐excess samples. The TEM analysis shows their significant difference in grain‐boundary (GB), where abnormal GB with a width of 10–15 nm is observed in Ba‐excess sample. The photocurrent switching phenomenon is described to the competition between the asymmetrical Schottky barriers induced PV effect and intrinsic FPV effect. Widen GB in Ba‐excess BaTiO3 ceramics restrains the intrinsic FPV effect and results in the switching behavior. This study offers direct evidence of the vital role of GB in FPV effect and may promote the development of photovoltaic devices. [ABSTRACT FROM AUTHOR]

The wide‐bandgap, semiconducting ternary compound Hg3Se2I2 has shown promise as room‐temperature hard‐radiation detector. Since this compound was first reported, there has been significant improvement in crystal growth using a chemical vapor transport method with a polyethylene growth agent. To study the effects of this additional precursor on crystal quality, the nature of radiative and nonradiative defects using photoluminescence (PL) and photocurrent (PC) studies of Hg3Se2I2 single crystals are investigated. In contrast to earlier studies, excitation intensity‐dependence of PL emission shows that the near‐band‐edge (NBE) emission bands are all excitonic in nature. The PL intensity decreases with increasing temperature, with the higher energy peaks quenching by 40 K and the deeper levels quenched after 110 K. The PC spectra show a complex structure at room temperature related to NBE transitions in the band structure, while at low temperature only the direct gap transition is observed due to phonons freezing out. The PC spectra at low temperature also indicate several midgap levels that are attributed to native defects within the bulk crystal. These results indicate that the high quality of Hg3Se2I2 single crystals is maintained when the transport agent is used during growth, although there are still a variety of defects present. The defect levels of the antiperovskite semiconductor Hg3Se2I2 are investigated. Photoluminescence spectroscopy reveals four below‐gap bands which are attributed to bound excitons. Photocurrent spectra of Hg3Se2I2 have a complex structure, with several band‐edge transitions at room temperature which converge to one peak at low temperatures as phonons freeze out, revealing several midgap levels present at low temperature. [ABSTRACT FROM AUTHOR]

Dielectric breakdown is a very important factor determining the reliability of multilayer ceramic capacitors, and its microscopy imaging is still a pending work so far. Here, a high resolution scanning pyroelectric microscopy (SPeM) is developed for direct imaging dielectric failure behavior of multilayer ceramic capacitors (MLCCs) due to the combination of pyroelectric effect and scanning thermal microscopy. Subsurface dielectric‐breakdown regions along the depth profile inside BaTiO3 capacitors are successfully visualized by measuring 2ω‐pyroelectric current via the frequency modulated SPeM. It provides a new approach for exploring subsurface dielectric breakdown microstructures, and for further understanding the underlying physical phenomena inside the MLCCs. A high resolution scanning pyroelectric microscopy (SPeM) is developed for direct imaging dielectric failure behavior of multilayer ceramic capacitors (MLCCs) due to the combination of pyroelectric effect and scanning thermal microscopy, providing a new approach for exploring and further understanding the underlying physical phenomena inside the MLCCs. [ABSTRACT FROM AUTHOR]