Modification of optical and electrical properties of nanocrystalline VO2·0.5 H2O/ZrV2O7: influence of Cs, Cr and Ga doping

Abstract

A facile and economical route has been demonstrated for large-scale synthesis of nano VO2·0.5 H2O/ZrV2O7 and it is doping with Cs, Cr and Ga using combined precipitation-hydrothermal that followed by a gentle heating at low temperature. The growth mechanism of doping is discussed and investigated by XRD, SEM, TEM, Raman, TGA, DSC, and UV–vis spectroscopy. The band gap is enhanced with doping. The results show that the all composites have a negative thermal coefficient in the range 25–100 °C while it has a positive thermal coefficient in the range 100–300 °C. Also, Cs doped has increase in conductivity as compared to Cr doped which may be due to the enhancement of oxygen vacancies as resulted from addition of low valence cations. Doping with Cr or Cs show the contribution of grain and grain boundary properties, respectively, while the doping with Ga shows the insulating behavior. Keywords: VO2·0.5 H2O/ZrV2O7, Doping, Band gap, Grain and grain boundary, Ionic conductivity, Electrical conductivity