Ac conductivity of BaTiO3 containing (90V(2)O(5)-10P(2)O(5)) oxide glasses dispersed with nanocrystalline particles

The frequency dependent AC conductivity (sigma (ac)) of some new multicomponent (1 - x) (90V(2)O(5)-10P(2)O(5)) + xBaTiO(3) (x = 0.1 to 0.9) type glasses containing nanocrystalline BaTiO3 particles (observed from the transmission electron microscopic study) has been reported in the temperature range 80-400 K. The behavior of sigma (ac) is broadly similar to what has been observed previously in many other amorphous semiconductors and polymers (namely nearly linear frequency dependence and weak temperature dependence). Analysis of the experimental conductivity data shows that Long's overlapping large polaron tunneling (OLPT) mechanism is the most probable mechanism of conduction for the present BaTiO3 doped glasses. The Quantum mechanical tunneling (QMT) model and the classical hopping of electrons over a barrier can, however, explain the AC conductivity data only below theta (D)/2-160 K (theta (D) is the Debye temperature). Reasonable values of the relaxation time and barrier heights related to the models have been obtained from the fits of the conductivity data. (C) 2001 Kluwer Academic Publishers.