Abstract
Dielectric anomaly of disordered PSN appears at higher temperature than that of the ordered PSN, whereas in PST the situation is opposite. TEM studies of Pb[Sc0.5(Nb1-xTax)]O3 single crystals (x = 0, x = 1, x = 0.3) show that PSN crystals are grown in more disordered state than the PST crystals and the PSNT crystals are the mostly ordered: linear sizes of {111} ordered regions are 3–4 nm, 30–40 nm and 60–100 nm, respectively. The behaviour is associated with nonlinear and spatial correlation contribution to the random field distribution function.