Dielectric relaxation studies in some rare earth ions doped vanado-tellurite glasses

Vanado-tellurite glasses containing La and Ce rare earth ions were investigated for dielectric properties in the frequency range 50Hz to 5MHz and temperature range 300K to 500K. The dielectric constant and dielectric loss were found to decrease with increase in frequency in both the series of glasses. Activation energies for dielectric losses derived by employing HuntÂ’s model 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 processwere found to be in close agreement with dc activation energies. BNNÂ’s linear relation between ac and dc conductivities has been verified in both the glass systems. It is for the first time that Hunts and BNNÂ’s theories have been verified in rare earth ions doped tellurite glasses.