Ordering and electric-field effects on the ferroelectric phase transition of some relaxors

Abstract Optical transmission and small-angle light scattering (SALS) of PbSc½Ta½O3 (PST) and PbSc½Nb½O3(PSN) crystals with different degree of ions ordering, as well as PbMg⅓Nb⅔O3 (PMN) and PbZn⅓Nb⅔O3 (PZN) crystals were investigated under various dc-field. The first direct experimental evidence for the percolation nature of a spontaneous ferroelectric phase transition accompanied by an anomalous peak of SALS intensity has been received both in ordered and disordered stoichiometric PST and PSN crystals without electric field application. The application of electric field above some critical value is required to induce percolation phase transition in PMN crystal. Phase diagrams, with respect to dc field and temperature, were proposed for PST, PSN and PMN crystals.