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A novel low-temperature sinterable microwave dielectric ceramic was successfully developed by adding low-melting-point Bi2O3–ZnO–B2O3–SiO2 (BBSZ) glass to ZnZrNb2O8 (ZZN) ceramic. The influence of BBSZ glass on the densification behavior and microwave dielectric properties of ZZN ceramic was systematically investigated by means of an X-ray diffractometer, a scanning electron microscope and a network analyzer. By adding an appropriate amount of BBSZ glass into ZZN ceramic, the sintering temperature was lowered to 950 °C, indicating that BBSZ glass was an effective firing agent for ZZN ceramic. Furthermore, favorable microwave dielectric properties of ɛr = 32.5, Q×f = 38,400 GHz and τf = − 51 ppm/°C were yielded in the ZZN sample with 6 wt% BBSZ glass addition, simultaneously maintaining uniform and compact microstructure. The chemical compatibility between the present composite and Ag electrode was also investigated for commercial applications. [ABSTRACT FROM AUTHOR]

Abstract: Bi2Fe4O9 powders with different morphology and particle size have been prepared via surfactant-free solvothermal route with water and water–ethanol mixed solvents. The as-synthesized samples were characterized by powder X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy and UV–vis spectroscopy. The effect of the solvent on the morphology of Bi2Fe4O9 crystals and the formation process of rod-like microrods and defective crystals were investigated. Rod-like and cubic shape Bi2Fe4O9 crystals could be easily obtained by changing the volume ratios of H2O/EtOH. The results indicate that the rod-like Bi2Fe4O9 crystals could be formed in the more ionic solvent, and the anisotropic nature of the crystal structure may be responsible for the formation of rod-shape. In addition, the optical properties and photocatalytic activity of the Bi2Fe4O9 samples were investigated. The lower photocatalytic activity of Bi2Fe4O9 microrods could be attributed to their larger particle size, smaller specific surface areas and smaller bandgap. [Copyright &y& Elsevier]

Abstract: The nano-scaled powders of a high Curie temperature piezoelectric system with a composition of 0.63Bi(Mg1/2Ti1/2)O3–0.37PbTiO3 (0.63BMT–0.37PT) have been synthesized via a citrate sol–gel method. The thermal decomposition process of the as-prepared xerogel was investigated through the thermo-gravitometry and differential scanning calorimetry. The lattice structure of the powders as the function of heat-treatment temperatures was explored by using X-ray diffraction, Fourier-transform infra-red and Raman spectra. The results indicated that the transparent gel could be obtained via the chelate reaction of citric acid with ethylene glycol and ethanolamine assist. Gels can be transformed into crystallite powders with a single-phase perovskite structure when heat-treated at 600 °C for 3 h, much lower than that of traditional solid-state reaction method. The sol–gel derived 0.63BMT–0.37PT ceramics sintered at 1020 °C exhibit excellent dielectric, ferroelectric and piezoelectric properties of T c = 463 °C, , tan δ = 0.063, P r = 22.1 μC cm−2 and d 33 = 230 pC N−1. Moreover, a small amount of Mn2+ doping could cause the reduced leakage current and slightly increased T c values. [Copyright &y& Elsevier]