Enhanced mechanical and ferroelectric properties through grain size refinement in site specific substituted lead free Na0.5-xKxBi0.5TiO3 (x=0-0.10) ceramics

Site specific substitution of K-ion at Na-site (i.e., Na0.5-xKxBi0.5TiO3 -NKBT) by varying its concentration from x = 0-10 mol% decreased the grain size significantly from 14 mu m (x = 0) to 1.1 mu m (x = 10). The substituted K-ion acts as a grain growth inhibitor to attain fine grained ceramics. Coercive field (E-c) showed a strong grain size dependence and observed a maximum softening of 43% in Ec i.e., 63 kV/Cm (x = 0) to 36 kV/cm (x = 10). Vickers hardness also displayed strong grain size dependence and attained a maximum of 10.2 GPa for NKBT-10 ceramics, which is double than parent NBT and other commercial lead based piezo-ceramics such as PZT and PLZT. (C) 2017 Elsevier B.V. All rights reserved.