[en] In barium strontium titanate (Ba_xSr_1-xTiO₃) ceramics, obvious tunabilities of both dielectric permittivity and loss tangent under external DC bias field were observed. The temperature and frequency dependences of nonlinear dielectric properties were studied. Polarizing process was carried out to evaluate the influence of domain reorientation on dielectric nonlinearity in the ferroelectric polycrystalline samples. The nonlinear variation of dielectric properties under external DC bias field was tentatively explained

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[en] Highlights: • The BaTiO₃–ZnNb₂O₆ ceramics were prepared by a solid state reaction method. • ZnNb₂O₆ addition lowers sintering temperature, decreases grain size, while introduces second phase (Ba₂Ti₅O₁₂) for x ≥ 7.26 wt%. • T_C shifts to lower temperature with the substitution of the Ti-site by Zn²⁺ and Nb⁵⁺ in BT system. • P_r of BT-based ceramics are decreased effectively by addition of ZnNb₂O₆. • The dielectric breakdown strength is enhanced with the increasing doping level of ZnNb₂O₆ and reaches a maximum value at x = 7.26 wt%, exhibiting a maximum energy storage capability. -- Abstract: BaTiO₃ ceramics were prepared using solid state reaction with addition of ZnNb₂O₆, to investigate the effects of ZnNb₂O₆ addition on structure and properties. The results show that the ZnNb₂O₆ addition lowers sintering temperature, decreases grain size, while introduces second phase (Ba₂Ti₅O₁₂) for x ≥ 7.26 wt%. The dielectric breakdown strength is enhanced with the increasing doping level of ZnNb₂O₆ and reaches a maximum value at x = 7.26 wt%, exhibiting a maximum energy storage capability

[en] Highlights: • Semiconductive BaO–B_2O_3–SiO_2–Na_2CO_3–K_2CO_3 glass was added to Ba_0_._4Sr_0_._6TiO_3 ceramic. • Sintering temperature was lowered about 150 °C with a high relative density (∼98%). • Dielectric constant of BST glass ceramics decrease with increasing Na_2CO_3 content. • BDS and energy density of BST glass ceramics increase with increasing Na_2CO_3 content. - Abstract: Semi-conductive BaO–B_2O_3–SiO_2–Na_2CO_3–K_2CO_3 glass additives were added to Ba_0_._4Sr_0_._6TiO_3 (BST) ceramics to investigate its influences on the microstructure, dielectric properties, breakdown strength (BDS), and energy storage density. The sintering temperatures were lowered about 150 °C with a high relative density (∼98%). X-ray diffraction patterns of all BST glass ceramics suggest perovskite structures without any detectable secondary phase. Room temperature dielectric constant of BST glass ceramics decreases with increasing Na_2CO_3 content. BDS and energy storage density of BST glass ceramics increase with increasing Na_2CO_3 content, and reach their maxima of 280 kV/cm and 0.72 J/cm"3 at the highest Na"+ and K"+ content. These results suggest that the BST glass ceramics could find their potential applications in energy storage capacitor devices

[en] NanoPt intercalated Zn–Ti layered double hydroxides (LDHs) have been synthesized by ionic exchange and photochemical reduction method from Zn–Ti LDHs in H₂PtCl₆ solution. X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), N₂ adsorption at 77 K, UV–vis analysis and the electrochemical impedance were adopted to investigate the structure, surface, micromorphology, photoresponsive and electrochemical properties of the as-synthesized samples. The combination of Zn–Ti-LDHs and Pt introduces some properties of Pt into photocatalysis such as excellent conductivity and controllability. Remarkable 17-fold enhancement in the degradation of rhodamine B (RhB) reaction was observed on as-prepared Pt/Zn–Ti LDHs compared with pure Zn–Ti LDHs under simulated sunlight irradiation. The enhanced photocatalytic activity could be attributed to high specific surface (111.46 m²/g), extended photoresponding range, the negative shift in the flat-band potentials and the high migration efficiency of photoinduced electrons, which may suppress the charge recombination effectively.

[en] Piezoelectric resonance current and switching current of 0.68Pb(Mg_1/3Nb_2/3)O₃-0.32PbTiO₃ (PMT-32%PT) single crystal were investigated by a stepwise electric field. As the reversely applied field increased from the coercive field to higher levels, high frequency resonance current always existed while the low frequency resonance current was replaced by a peak in the switching current gradually. This phenomenon is discussed based on a domain reversal process. The maximum switching current observed in switching current is fitted well using the equation proposed by Merz. This indicates that domain wall growth, instead of domain nucleation, plays an important role in that process. (fast track communication)

[en] The piezoelectric coefficients (d₃₃, -d₃₁, d₁₅, g₃₃, -g₃₁, g₁₅) of soft and hard lead zirconate titanate ceramics were measured by the quasi-static and resonance methods, at temperatures from 20 to 300 ⁰C. The results showed that the piezoelectric coefficients d₃₃, -d₃₁ and d₁₅ obtained by these two methods increased with increasing temperature for both hard and soft PZT ceramics, while the piezoelectric coefficients g₃₃, -g₃₁ and g₁₅ decreased with increasing temperature for both hard and soft PZT ceramics. In this paper, the observed results were also discussed in terms of intrinsic and extrinsic contributions to piezoelectric response.

[en] Direct diffraction evidence for structurally frustrated relaxor ferroelectric behavior in the form of one-dimensionally correlated, off-center displacements of Ti ions within the TiO₆ octahedra of CaCu₃Ti₄O₁₂ (CCTO) has been obtained. When coupled with the observation of a ferroelectric effect, important implications for the understanding of the extraordinary dielectric properties of CCTO arise. That the incipient ferroelectric behavior is correlated only along one-dimensional <001> columns of TiO₆ octahedra in the absence of an applied electric field offers a crucial insight into the underlying nature of CCTO and suggests the existence of a unique class of structurally frustrated, ferroelectric relaxors

[en] In this paper, we design a novelty metasurface for achieving radar cross section (RCS) reduction. The proposed metasurface can achieve phase difference by rotating its unit cells to different rotating angles as traditional Pancharatnam–Berry (P–B) phase. However, compared with traditional P–B phase metasurface, the unit cells of this proposed metasurface do not possess certain period, it indicates that random phase gradients can easily produce on this proposed metasurface. The direction and the scalar of these produced random phase gradients are all random, and the incident waves can be diffused by these random phase gradients, realizing wideband, wide angle, polarization-independent RCS reduction. The design of units without fixed period increases the freedom of controlling electromagnetic wave. Both the simulation and experiment show that the proposed metasurface is valuable for stealth technology.

[en] The processing route of barium stannate titanate ceramics were optimized to prepare full composition range solid solution sample. The phase structure, microscopic morphology and dielectric properties of barium stannate titanate ceramics were studied. X-ray diffraction patterns indicated that the samples are of single perovskite structure. Linear empirical relationship between crystal lattice and tin content was proposed. This relationship is valid covering the full composition range, which suggests that this solid solution system is ultimate mutual soluble. The phase transition behavior was studied and a phase diagram was obtained based on the dielectric measurements