Interrelation of electrostriction with phase transition diffuseness —improvement of the temperature characteristics of electrostriction—

Recently-developed electrostrictive materials have been classified on the basis of the origin of their diffuse phase transitions for the purpose of seeking how to improve the temperature characteristics of transducers. A simple interrelation between the temperature coefficient of electrostriction and the phase transition diffuseness is demonstrated in the solid solution systems Pb(Mg_1/3Nb_2/3)O₃–Pb(Mg_1/2W_1/2)O₃ and Pb(Mg_1/3Nb_2/3)O₃–PbTiO₃, in conjunction with the short-range order in B-site cations. A cluster model, extended from the random compositional fluctuation model by Smolensky and Rolov, is proposed for a diffuse phase transition in complex perovskites with short-range ordering of the cation. Based on this model, the improvement of the thermostability has been made in the Pb(Mg_1/3Nb_2/3)O₃–PbTiO₃ ceramics by adding Pb(Mg_1/2W_1/2)O₃ or Ba(Zn_1/3Nb_2/3)O₃, resulting in a temperature coefficient less than 1% deg⁻¹.