B-site vacancy as the origin of spontaneous normal-to-relaxor ferroelectric transitions in La-modified PbTiO3

Abstract

The site vacancy responsible for the manifestation of a spontaneous normal-to-relaxor transition was investigated using La-modified PbTiO3 as a model perovskite system. The two cation-site defects relevant to the present study are the A-site (Pb site) and B-site (Ti site) vacancies. To clearly elucidate the type of vacancy involved in the spontaneous transition, we have developed a sintering route that suitably adjusts the relative concentration of these two distinct cation-site vacancies. Using this processing scheme, we have shown that the microcompositional inhomogeneity caused by the B-site vacancy is primarily responsible for the manifestation of relaxor behavior from normal ferroelectricity in La-modified PbTiO3.