Influence of oxygen annealing on the dielectric properties ofSrBi2(V0.1Nb0.9)2O9 ceramics

Abstract

The influences of O2 and N2 annealing on the dielectric properties ofSrBi2(V0.1Nb0.9)2O9 (SBVN) ferroelectrics were studied. Ceramic samples wereprepared by reaction sintering a powder mixture of constituent oxides at 950 °Cfor 2 h in air. Some samples were also subsequently annealed at 800 °C for3 h in O2 or N2. With O2 annealing, the Curie point of the SBVNferroelectricschanged from ~433 to ~438 °C and the peak dielectric constant increased from~760 to ~1010 (at 100 kHz). However, no change in the Curie pointwas found with N2 annealing. Furthermore, O2 annealing was found toreduce significantly both the dielectric constant and loss tangent of the SBVNferroelectrics at frequencies below 1000 Hz. XRD results revealed a smallreduction in the lattice constants with O2 annealing, but no appreciablechange with N2 annealing. In addition, no detectable change in the microstructureof the SBVN samples was found with annealing. These results imply that someV4+ ions, which are compensated by the formation of oxygen vacancies, existedin the SBVN ferroelectrics prior to O2 annealing. V4+ ions were oxidized to V5+with O2 annealing, which resulted in improved dielectric properties.