Dielectric anomalies of the relaxor-based 0.9Pb(Mg_(1/3)Nb_(2/3))O_3-0.1PbTiO_3 single crystals

摘要

The temperature, frequency, and orientation dependence of complex electrical permittivity in 0.9Pb(Mg_(1/3)Nb_(2/3))O_3-0.1PbTiO_3 (0.9PMN-0.1PT) unpoled single crystals have been investigated in detail. The spontaneous ferroelectric-to-relaxor (FE-R) phase transition was observed in 0.9PMN-0.1PT crystals at about 280 K. Interestingly, the Vogel-Fulcher-type anomaly of the dielectric constant has been obtained, with the fitted temperature T_f being very close to this FE-R phase transition temperature. A small frequency dependence of electric permittivity magnitude appears at and below 280 K. The changes of the polar nanoregion subsystem and the peculiarities of the domain structure play an important role in the dielectric anomalies and the appearance of the FE-R crossover region.