SELF-LOCALIZED CARRIER STATES IN DISORDERED FERROELECTRICS

A theory of self-localized states of free carriers near polarization f luctuations (fluctuons) in disordered ferroelectrics is developed. Cal culations are carried out for the model disordered ferroelectric K1-xL ixTaO3 (x much less than 0.05). The basic characteristics of the fluct uon the energy and radius of the fluctuon state - are calculated as fu nctions of the impurity dipole concentration and temperature. The theo ry predicts the appearence of stable fluctuon states in both the mixed ferroelectric-dipole-glass phase (a dipole glass is the electric anal og of a spin glass) and the dipole-glass state of disordered ferroelec trics. The possible role of fluctuons in kinetic phenomena such as con ductivity in these substances is discussed. (C) 1997 American Institut e of Physics.