ON THE MECHANISM OF ELECTRICAL RELAXATION IN NA-CONDUCTIVE PHOSPHATE-GLASSES()

The crossover from a frequency independent to a frequency dependent ac response has been studied in glasses with the composition 37.2Na(2)O- 12.8CaO(5).50P(2)O(5) and 30Na(2)O-5CaO-7.5Al(2)O(3)-57.5P(2)O(5) (mol %) containing 5 X 10(-3) less than or equal to mol% Ag2O less than or equal to 5 x 10(-1). Recently, we have established that in these glass es the diffusion coefficient of guest silver ions varies in space. In this case, as a first approximation, the diffusion coefficient may be considered as a constant within regions whose size is no less than 10 nm across. We assume that the diffusion of sodium ions can be given by the D(r) coefficient with the same spatial dispersion as that of silv er ions. It is demonstrated that the frequency dependence of ac respon se is in fair agreement with the assumption. (C) 1997 Elsevier Science B.V.