Effects of zirconium on the structural and dielectric properties of (Ba, Sr)TiO₃ solid solution

Abstract

The effects of zirconium on (Ba, Sr)TiO₃ solid solution are studied by preparing (Ba_0.75Sr_0.25) (Zr_y Ti_1-y)O₃ (BSZT) ceramics with γ ranging from 0 to 0.15. With increased incorporation of zirconium the lattice parameters increase with decreasingc/a ratio, while a linear relationship is found between (a ² c)^1/3 values and the content of zirconium. The Curie temperature (T _c) is also lowered linearly with increasing γ. The Curie temperature of the (Ba_1-xSr_x (Zr_yTi_1-y)O₃ system can be estimated byT _c = 125 − 270x − 350_y (°C). Observations of microstructures also show that a small amount of zirconium promotes the grain growth, while a higher content will then inhibit it. Dielectric properties of BSZT dielectrics and BSZT-based boundary layer (BL) capacitors are also correlated to have similar temperature dependence, where the maximum dielectric constant at room temperature is found aty = 0.1.