Ionic conductivity and conductivity relaxation of potassium tellurite glasses

The electrical conductivity and conductivity relaxation of xK2O-(100-x)TeO2 glasses have been investigation in the frequency range 40 Hz to 200 kHz and temperature range 300 to 473 K. From the density and molar volume, it may be noticed that with increasing K2O content the density decreases while the molar volume increases highlighting the fact that more nonbridging oxygens (NBOs) are formed in the network as the concentration of K2O is increased. The Anderson-Stuart model was employed to explain the dc activation energy. The frequency-dependent electrical data have been analyzed in the framework of the conductivity and modulus formalisms. The decrease of the conductivity relaxation time with increasing content of K2O was explained in the framework of the structural model of tellurite glasses. The variation of the stretched exponential parameter β with composition was compared with those of lithium and sodium tellurite glasses and was explained in terms of cation-cation distance correlation. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)