Effect of MnO₂ on the Piezoelectric Properties of (1-x)(Na0.5K0.5)NbO₃–xBaTiO₃ Ceramics

(Na 0.5 K 0.5 )NbO 3 (NKN) and BaTiO 3 (BT) ceramics form a homogeneous solid solution. The relative density of the (1- x )NKN– x BT solid solutions significantly decreased when x ≤0.07. Although the relative density of the 0.95NKN–0.05BT ceramic was very low, it had a high d 33 value of 134 pC/N. MnO 2 was added to improve the piezoelectric properties of the 0.95NKN–0.05BT ceramics by enhancing their sinterability. The addition of MnO 2 increased the density of the specimens, as well as improving the piezoelectric properties. The 0.9 mol % MnO 2 added 0.95NKN–0.05BT ceramics showed the good piezoelectric properties of k p =0.31, d 33 =194 pC/N and ε 3 T / ε 0 = 800.