Dependence of dielectric properties on microstructural characteristics of (Ba0.7Sr0.25Ca0.05)(Ti0.9Zr0.1)O3 ceramics

The dielectric properties and microstructure of (Ba0.7Sr0.25Ca0.05)(Ti0.9Zr0.1)O3 (BSCTZ) ceramics have been controlled by ZnO addition and/or two-step sintering. The single-phase perovskite structure was observed for all investigated specimens with ZnO addition in the range of 0≤x≤0.15 wt%. With increasing ZnO content, the unit cell volume increased due to the Zn2+ substitution for Ti4+, and the dielectric constant (εr), dielectric loss (tan δ), and breakdown voltage (Vb) of the specimens decreased. The specimens sintered by a two-step method showed high density and homogeneous microstructure with smaller grains which enhanced Vb, whereas εr decreased and tan δ increased slightly. The dielectric properties of the two-step sintered specimens could be controlled by the first-stage sintering temperature T1 because the grain size was more strongly dependent on T1 than on the ZnO content. P–E hysteresis loops were not changed remarkably by ZnO addition and/or two-step sintering.