Enhanced dielectric relaxor properties in (1 - X)(K_0.5Na _0.5)NbO₃-x (Ba_0.6Sr_0.4) _0.7Bi_0.2TiO₃ lead-free ceramic

The (1 - x)(K_0.5Na_0.5)NbO₃-x(Ba _0.6Sr_0.4)_0.7Bi_0.2TiO₃ [(1 - x)KNN-xBSBT] lead-free ceramics were prepared by the conventional solid-state sintering method. The effects of BSBT doping on the phase structure, microstructure and dielectric properties of the ceramics were studied. The experiment results reveal that the phase transitional behavior is induced and the average grain size firstly increases and then decreases with increasing the BSBT content. Also, the dielectric relaxor behavior and the diffusion coefficient of the ceramics increase with increasing the BSBT doping. The comparison of the relaxor behavior based on empirical parameters (ΔT _diffuse), and the slimmer P-E hysteresis loops further confirm the enhanced relaxor behavior in (1 - x)(K_0.5Na_0.5)NbO ₃-x(Ba_0.6Sr_0.4)_0.7Bi _0.2TiO₃ lead-free ceramics. Excellent dielectric properties of 0.97KNN-0.03BSBT ceramics are ε > 2000 and tanδ < 3% at a broad usage temperature range (100-400 °C), which shows that this system is a promising candidate material for the high temperature multilayer ceramics capacitor.