Preparation, dielectric relaxation, and x-ray diffraction at various temperatures of Pb(Sc1/2Ta1/2)O3 ceramics

Pb(Sc1/2Ta1/2)O3 (PST) ceramics with high quality were successfully prepared by a solid-state reaction technique with the designed double crucible configuration. The pure cubic perovskite phase with the ordering degree of 0.55 was detected. Scanning electron microscopy analysis displayed that PST ceramics present dense structure with the grain size of 2–3 µm. The nearly stoichiometric element ratio and uniformly elemental distribution were observed by using an energy dispersive spectrometer and mapping. The temperature dependence of the dielectric constant implied that strong frequency dispersion with the diffuseness exponent of 1.54 was found in PST, suggesting the nature of relaxation. The dielectric maximum and the temperature at dielectric maximum were 7300 and −19.99 °C, respectively. The analysis of the inverse of dielectric permittivity indicated that polar nanoregions (PNRs) began to appear, grow, and interact with decreasing temperature below 193.3 °C. X-ray diffraction patterns at various temperatures suggested that the phase structure and the B-site ordering degree hardly change from −100 to 350 °C. Moreover, B-site ions arrangement with various ordering degrees regulated the formation of nanodomains or macrodomains configuration by affecting the correlated motion of Pb ions. The disordered B-site ions’ arrangement breaks long-range correlations of Pb ions and leads to the formation of PNRs.