Preparation and characterization of binary V2O5-Bi2O3 glasses

Abstract

Characterization of the binary V2O5-Bi2O3 glasses prepared by rapidly quenching the melt has been made from the studies of X-ray diffraction, scanning electron microscopy, infrared absorption, differential thermal analysis, electron paramagnetic resonance, chemical analysis, density and electrical properties. Stable glasses are obtained for 95 to 75 mol % V2O5 by quenching on a stainless steel substrate, while quenching on a copper substrate extends the glass formation range from 95 to 70 mol % V2O5. The V-O bond vibration in the glasses occurs at 1020 cm−1 and the V5% ion exists in six-fold coordination as in crystalline V2O5. All the glasses appear to be in single phase. The spin concentration in the glasses is found to be independent of temperature. A second heat-treatment at 255° C develops crystalline phase in the glasses. Unlike infrared absorption, electron paramagnetic resonance, density and chemical compositions, the electrical and thermal (DTA) properties are found to be slightly sensitive to the thermal history of preparation of the glasses. The high-temperature (300 to 500 K) conduction in the glasses seems to be due to adiabatic hopping of polarons. The thermopower is observed to be independent of temperature and provides evidence for small polaron formation in the glasses.