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Complex impedance spectra of BST ceramics were measured at different temperatures, and the results reveal that all the centers of the semicircles lie below the real axis, and the area of the semicircles decreases with the increasing temperature. Activation energy of grains and grain boundaries was obtained from a classical Arrhenius relation. The results show that the activation energy of grains and grain boundaries of undoped BST ceramics is 0.98 and 0.97 eV, respectively. After doping B2O3–SiO2, the activation energy of grain increased to 1.12 eV, which was due to B2O3–SiO2 redistribution to the grain boundary during the cooling process. The activation energy of grains increased to 1.16 eV after 1 mol% MgO doping, which was caused by the decrease of the oxygen vacancy concentration and the increase of the potential barrier of the grain boundary.

BaxSr1−xTiO3 (BST) thin films were grown on different substrates with or without LaNiO3 (LNO) layer by a modified sol–gel process. The BST thin films obtained have full perovskite phase with dense and crack-free surface. BST thin films on different substrates with LNO layer show (100) preferential orientation, the texture coefficient (TC) value is calculated to be about 42.7%, whereas those without LNO layer show a fairly reduced preferential orientation, the TC value is just about 24.8%. It is considered that the preferential orientation is induced by the interface stress between LNO and BST. Electrical property measurements showed that BST thin film with a LNO interlayer has lower capacitance and larger dielectric loss, which is due to smaller grains of the thin film.

Ba0.65Sr0.35TiO3 (BST) thin films have been prepared by radio frequency magnetron sputtering on fused quartz at different substrate temperatures. Optical constants (refractive index n, extinction coefficient k) were determined from the optical transmittance spectra using the envelope method. The dispersion relationship of the refractive index vs. substrate temperature was also investigated. The refractive index of BST thin films increased from 1.778 to 1.961 (at λ = 650 nm) as deposited temperature increases from 560°C to 650°C. The extinction coefficient of as-deposited BST thin films increased with the increase of the oxygen-to-argon ratio, which was due to the change of the film stoichiometry, structure, and texture of BST thin films. The oxygen-to-argon ratio also affected the fluorescence spectra. The fluorescence peaks intensity was greatly increased, apparent frequency shift was detected, and the linewidth became narrow as the ratio of oxygen to argon increased from 1:4 to 1:1. The fluorescence spectra also indicated the band transition of BST thin films was an indirect gap transition.