Thermomechanical behaviors and antiferroelectric superstructures in Pb(Yb_1/2Nb_1/2)O₃–rich Pb(Yb_1/2Nb_1/2)O₃–Pb(Fe_1/2Nb_1/2)O₃ solution system

Abstract

The phase transition behavior of the pseudo-binary (1-x Pb(Yb_1/2Nb_1/2)O₃–xPb(Fe_1/2Nb_1/2)O₃ solid solution has been investigated by thermal expansion and x-ray diffraction. The deviation from the high temperature thermal expansion at temperature near the paraelectric-antiferoelectric (ferroelectric) transition can be explained by the elastic strain coupling to the dipole moments via the electrostriction. For 0<x<0.11, the transition is characteristically sharp, whereas for 0.14≤x≤0.3 it is diffise. X-ray diffraction of pure Pb(Yb_l/2Nb_1/2)O₃ shows a well-defined antiferroelectric superstructure. With the increasing Pb(Fe_1/2Nb_1/2)O₃ concentration, the order-disorder as well as displacement superstructure is observed to diminish. Such structural manifestation on transition seems to be connected with the dielectric behavior.