Unified conduction mechanism in unconventional VZnCaFeO glasses

Unconventional glasses with (70-x)%V2O5 - x%ZnO - 10%CaO-20%FeO compositions (where x=0, 2.5, 5, 7.5, 10, 12.5 and 15 mol %) were prepared by a normal melt-quench technique. We investigated the DC and AC conductivities of these glasses as functions of temperature and frequency. We have noted that activation energy and pre-exponential factor of the DC conductivity both vary with composition and satisfy Meyer-Neldel rule (MNR). The AC conductivity exhibited a universal dynamic response: sigma(AC)=A omega(s). The obtained results of the DC. AC and exponent factor S were discussed in terms of the modified correlated barrier hopping model, which assumes that the relaxation time should contain a Meyer-Neldel rule term. An agreement between experimental and theoretical results suggests that the conduction mechanism could be hopping of polarons over barriers. (C) 2014 Elsevier By. All rights reserved.