Structural and Piezoelectric Properties of ($1-x$)(Na0.5K0.5)NbO3–$x$Ba(Ti0.9Sn0.1)O3 Lead-Free Ceramics

Lead-free ($1-x$)(Na0.5K0.5)NbO3–$x$Ba(Ti0.9Sn0.1)O3 ceramics doped with 1 mol % MnO2 [($1-x$)NKN–$x$BTS] were prepared by the conventional solid state method and their structural and piezoelectric properties were investigated. The ($1-x$)NKN–$x$BTS ceramics were well synthesized and a dense microstructure was achieved when sintered at 1050 °C for 8 h. The phase transition temperature of the tetragonal–cubic ($T_{\text{C}}$) peaks became broadened with increasing $x$, suggesting that a diffuse phase transition was induced and that the ceramic was changed gradually from a normal ferroelectric to a relaxor ferroelectric. The significantly enhanced piezoelectric properties of $d_{33}=256$ and $k_{\text{p}}=42$% were obtained for the 0.94NKN–0.06BTS ceramics.