ELECTROLUMINESCENCE STUDY OF POLARIZATION CHANGES IN LEAD MAGNONIOBATE CRYSTALS PULSED ELECTRIC-FIELDS

Electroluminescence is used to study changes in the polarization of cr ystals of a model ferroelectric relaxer, lead magnoniobate (PMN), in p ulsed electric fields. The amplitude of the electroluminescence pulses produced during polarization and depolarization of PMN crystals is fo und to depend on the duration of the applied electric field pulses if this duration is shorter than the most probable lime for polarization buildup. These data provide evidence of rapid changes in the polarizat ion through realignment of the domain and heterophase structure at tem peratures above the temperature for destruction of the induced macrodo main ferroelectric phase and evidence of an ''excited'' polarization s tate for short-lived pulses whose decay is accompanied by an enhanceme nt in the amplitude of the depolarizing luminescence pulse and by a re duction in the time delay of its emission following the end of the fie ld pulse. (C) 1997 American Institute of Physics.