Kinetics of electric-field-induced ferroelectric phase transitions in relaxor ferroelectrics

The kinetics of electric-field-induced ferroelectric phase transitions in relaxor ferroelectrics observed recently [S. B. Vakhrushev, J. M. Kiat, and B. Dkhil, Solid State Commun. 103, 477 (1997); B. Dkhil and J. M. Kiat, J. Appl. Phys. 90, 4676 (2001)] is analyzed in the framework of a dynamical model of relaxors which incorporates features of nonequilibrium glassy dynamics resembling that in dipole glasses, with the high polarizabity of the system being in the vicinity of the ferroelectric threshold. We show that the dynamical equations may be reduced to a Landau-type phenomenological polynomial in which the linear coefficient-zero-field-cooled permittivity-is a function of time. The theory adequately reproduces the features of electric-field induced polarization growth observed in the experiment.