The dependence of the piezoelectric properties on the differences of the A-site and B-site ions for (Bi 1− xNa x)TiO 3-based ceramics

Abstract

The effect of the differences of the ionic size R, atomic weight M, and electric negative X of the A-site and B-site ions of the ABO 3 perovskite (Bi 1− x Na x )TiO 3(BNT)-based solid solutions (where the complex of Bi and Na ions occupy the A-site and Ti ion is in the B-site) on the electromechanical coupling factors ( k 33, k p) of the piezoelectric ceramics was investigated. It was found that the coupling factors (k 33, k p) of the ceramics have little dependence on the parameters of ∣ M∣, ∣ R∣ and ∣ X∣, respectively. However, if a comprehensive weight factor F( w) is defined as F( w) = ∣ M∣ + ∣ R∣ + 100∣ X∣, which is a dimentionless number containing M, R and X, and can be regarded as the comprehensive factor related to the spontaneous polarization of a unit cell in a given ceramic system, one can fined that F( w) has good correspondence with the coupling factors k 33 and k p. With increasing of the value of F( w), the k 33 and k p increase consequently. From this viewpoint, new BNT-solid solution with larger electromechanical coupling factors would be predicted, and a new system of (Bi 1− x Na x )TiO 3-based solid solutions was invented in our group by using this method.