Dependence of dielectric relaxation on ac drive in [Pb(Mg1/3Nb2/3)O-3]((1-x))-(PbTiO3)(x) single crystals

Dielectric measurements under different ac drive voltages were performed on single crystals of (PbMg1/3Nb2/3O3)((1-x))(PbTiO3)(x) [(PMN)((1-x))(PT)(x) ] for 0 less than or equal to x less than or equal to 0.3. A significant in crease in permittivity was observed with increasing ac drive for all compos itions. The magnitude of increase depended on temperature and measurement f requency. Alternating current drive effects were found to be a low frequenc y phenomenon, primarily below 10(6) Hz. Three distinct ac-drive amplitude r anges are believed to exist in which various types of contributions dominat e in the dielectric relaxation: (i) a glassy mechanism is dominant at low d rives and gives rise to the typical relaxor ferroelectric characteristics i n the linear dielectric response, (ii) a kink or boundary vibration type wh ich is dominant at intermediate drives and gives rise to the nonlinearities in the dielectric response of relaxors under moderate ac drives, and (iii) a domain wall motion type which is dominant at higher drives and results i n polarization reversal. (C) 1999 American Institute of Physics. [S0021-897 9(99)02603-1].