Grain size control of lead-free Li0.06(Na0.5K0.5)0.94NbO3 piezoelectric ceramics by Ba and Ti doping

In this study, Ba- and Ti-doped Li0.06(Na0.5K0.5)0.94NbO3 [(1 − x)Li0.06(Na0.5K0.5)0.94NbO3–xBaTiO3 (x = 0–0.07)] ceramics were prepared by using conventional solid state reaction method, and the microstructure and electric properties of these samples were investigated. The grain size distribution of non-doped Li0.06(Na0.5K0.5)0.94NbO3 ceramics was relatively wide. The microstructure was composed of grains ranging 1.1–5.0 μm in size. However, with increasing Ba and Ti content, the grain size distribution became narrow and the average grain size decreased from 2.0 to 0.9 μm in size. In particular, the microstructure of x = 0.07 sample was composed of grains ranging 0.5–2.2 μm in size. As a result, the frequency dispersion of dielectric constant for the (1 − x)Li0.06(Na0.5K0.5)0.94NbO3–xBaTiO3 (x = 0–0.07) ceramics was reduced and the mechanical quality factor Qm was enhanced with increasing Ba and Ti content.