Conductivity studies on microwave synthesized glasses

Abstract

Conductivity measurements have been made on xV 2O5 -(100 - x) [0.5 Na2O + 0.5 B2O3] (where 10 ≤ x ≤ 50) glasses prepared by using microwave method. DC conductivity (s) measurements exhibit temperatureand compositional-dependent trends. It has been found that conductivity in these glasses changes from the predominantly 'ionic' to predominantly 'electronic' depending upon the chemical composition. The dc conductivity passes through a deep minimum, which is attributed to network disruption. Also, this nonlinear variation in σdc and activation energy can be interpreted using ion-polaron correlation effect. Electron paramagnetic resonance (EPR) and impedance spectroscopic techniques have been used to elucidate the nature of conduction mechanism. The EPR spectra reveals, in least modified (25 Na2Omol%) glasses, conduction is due to the transfer of electrons via aliovalent vanadium sites, while in highly modified (45 Na2O mol%) glasses Na+ ion transport dominates the electrical conduction. For highly modified glasses, frequency-dependent conductivity has been analysed using electrical modulus formalism and the observations have been discussed.