Phase diagram of thin-film relaxor PbMg1∕3Nb2∕3O3

Epitaxial heterostructures of pure perovskite relaxor ferroelectric PbMg1∕3Nb2∕3O3 thin films were grown by pulsed laser ablation varying the temperature of deposition. Dielectric response of the films was studied as a function of frequency, temperature, amplitude of ac electric field, and magnitude of dc electric field. The temperatures of dielectric maxima and the freezing temperatures determined in different regimes were analyzed with respect to the microstructure of the films. Different nonmonotonic tendencies in the behavior of the characteristic temperatures were found. The shift of the electric-field–temperature phase diagram of PbMg1∕3Nb2∕3O3 involving the sequence of transformations between paraelectriclike, glasslike, and ferroelectriclike states was suggested to be responsible for this. The shift of the phase diagram was found to be a monotonic function of the in-plane strain and it was ascribed to the internal electric field.