Relationship between Crystal Structures and the Relaxor Property of SrBi2(Ta2-x V x )O9 Ceramics.

Abstract

Here, V2O5 was used to substitute Ta2O5 in SrBi2Ta2O9 (SBT) and SrBi2(Ta2–xVx)O9 (SBTV) ceramics were formed. This study revealed that the substitution of Ta2O5 by V2O5 enhances the maximum dielectric constant (εm), increases the transition temperature, and reduces the sintering temperature of SBT ceramics. The diffraction intensity of c-axis-preferred orientation of SBTV ceramics increases with the increase in V2O5 concentration and sintering temperature. Disk-type grains were observed in the SBTV ceramics at higher sintering temperatures. By the Curie–Weiss law and modified Curie–Weiss law, the phase transitions of the SBTV ceramics were discussed. The dielectric properties of SBTV ceramics revealed that the relaxor-type ferroelectric characteristics became more obvious than the normal-type ferroelectric characteristics at high V2O5 concentrations and sintering temperatures. Raman spectroscopy was successfully used to study the lattice vibrational modes and structural transitions of SBTV ceramics. The spectra proved that as V2O5 was added to SBTV ceramics the octahedral TaO6 and VO6 structures exhibited a high frequency mode.