Effect of V2O5 concentration on the structural and optical properties and DC electrical conductivity of ternary semiconducting glassy nanocomposites

Abstract

Transition metal oxide–doped glassy nanocomposites of the form xV2O5-(1 − x) (0.05CdO-0.95ZnO) with x = 0.3, 0.5, 0.7, and 0.9 were prepared by the melt quenching route. Their microstructure was studied by X-ray diffraction (XRD), Fourier transform infrared spectroscopy, transmission electron microscopy, and optical absorption spectroscopy. The absorption bands at around 640–756 cm−1 are attributed to the antisymmetric stretching vibrations of VO2 groups. Physical attributes such as density, molar volume, oxygen molar volume, oxygen packing density, number of bonds per unit volume, and the average stretching force constant were evaluated. The XRD patterns reveal distinct diffraction peaks indicating crystallinity in the sample with x = 0.3, whereas significantly broadened patterns are observed in samples with x = 0.5, 0.7, and 0.9, reflecting a dominant amorphous nature. Different peaks in the XRD patterns indicate the formation of Zn2V2O7, ZnV2O6, CdV2O6, Cd2V2O7, and CdVO3 nanocrystallites, which are dispersed in the as-prepared glassy matrices. The optical absorption spectra show indirect transitions. With a rise in the concentration of V2O5, the optical transmission cutoff wavelength moves to higher wavelength. DC electrical conductivity was studied at various temperatures from 60–650 °C. The establishment of small polaron hopping was anticipated from the DC electrical conductivity data. DC conductivity was inferred with use of Mott's and Greaves's variable range hopping models.