RELATIVE STUDIES OF TRANSPORT PROPERTIES OF ZnO SUBSTITUTED LEAD VANADATE SYSTEM IN BOTH GLASS AND CRYSTALLINE FORMS

Abstract

Glasses of x( ZnO )(50 - x) PbO :50 V 2 O 5 system were prepared by melt-quench process in the range x = 0 mol % to 15 mol%. Measurements are reported for DC electrical conductivity as well as thermo electrical power for these samples in both glass and crystalline forms in the temperature range of 27°C and 227°C. The ESR studies of these samples at room temperature are reported. These spectra are characterized by well-resolved eight-line powder pattern. It is observed that the ESR spectra obtained in the crystalline form, the hyperfine structure is nearly smeared out and the spectra are characterized by a relatively broad line with an isotropic g value. The experimental results are analyzed with reference to Mott's model. The analysis shows that at high temperatures the temperature dependence of DC conductivity is consistent with Mott's model for both glass and crystalline samples. The high-temperature thermoelectric power was satisfactorily explained by Heikes' relation and the data also showed evidence of small polaron formation for glass form samples and large polaron formation in crystalline samples. These results indicate that all the glass samples lead metavanadate are n-type at room temperature and the crystalline samples are p-type at room temperature.