Abstract
Grain size and piezoelectric properties were investigated in (K, Na)NbO3 ceramics substituted with Sr for K and Na by 1 to 5 mol%. The grain size strongly depended on the A/B ratio in perovskite structure. The grain growth phenomenon was much like BaTiO3 semiconducting ceramics with donor additives. Piezoelectric properties were strongly affected by grain size. The powder obtained by calcining in advance the mixture of Nb2O5 and MnCO3 was used as a raw material powder for MnO addition. By adding 0.5 mol% MnO, grain growth anomaly was inhibited, and uniform and dense ceramic body was consequently obtained. It is necessary to realize the appropriate grain growth for working out piezoelectricity. The sample, in which Ba was substituted by 2 mol% and MnO was added by 0.5 mol%, showed kp = 0.443, Qm = 255, and d33 = 124 pC / N.
