Dielectric relaxation studies in transition metal ions doped tellurite glasses

Vanadotellurite and vanado-cobalt tellurite glasses were investigated for dielectric properties in the frequency range 50 Hz to 5 MHz and temperature range 300-500 K. Hunt's model has been invoked to analyze the data and the results indicated that the relaxation process has a local character and can be described by hops between each pair of sites. Activation energies for dielectric loss process were determined and they were in close agreement with dc activation energies. Barton, Nakijama and Namikawa's (BNN) linear relation between ac and dc conductivities has been verified in both the glass systems. (C) 2008 Elsevier Masson SAS. All rights reserved.