Dynamic Behavior of Polar Nanoregions in Re-Entrant Relaxor 0.6Bi(Mg1/2Ti1/2)O3-0.4PbTiO3

The existence of polar nanoregions (PNRs) is the most important characteristic of ferroelectric relaxors; however, the size determination and the dynamic of PNRs remain uncertain. Herein, it is revealed that a re-entrant relaxor behavior and ferroelectric-paraelectric transition coexist in complex perovskite oxide 0.6Bi(Mg1/2Ti1/2)O-3-0.4PbTiO(3.) Two dielectric anomalies, 1) the low-temperature re-entrant relaxor transition and 2) the high-temperature diffuse phase transition (DPT), are described by the phenomenological statistical model. The sizes of the two kinds of PNRs corresponding to two ferroelectric states were obtained. The dynamics of PNRs are analyzed using isothermal electrical modulus, which shows three critical temperatures associated with the DPT, the formation, and freezing of PNRs, respectively. The temperature evolution of the PNRs evolution depends on the stoichiometry of bismuth. The results provide new insights into the dynamic behavior of PNRs and the modification way of re-entrant relaxor behavior.