Effect of annealing-temperature-assisted phase evolution on conductivity of solution combustion processed calcium vanadium oxide films

Abstract

In thiswork, the effect of annealing temperature on the conductivity of solution-combustion-synthesized calcium vanadium oxide (CVO) films was studied. Conductivity was tailored by the appearance of the phases like CaVO<inf>3</inf>, CaV<inf>2</inf>O<inf>5</inf> and Ca<inf>2</inf>V<inf>2</inf>O<inf>7</inf> as a function of annealing temperature; CaVO<inf>3</inf> and CaV<inf>2</inf>O<inf>5</inf> are responsible for high conductivity, whereas V5+ presence in Ca<inf>2</inf>V<inf>2</inf>O<inf>7</inf> contributes towards dielectric nature. Evolution of phases of CVO was identified through X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. A detailed conductivity measurement as a function of annealing temperature helps us to identify the decreasing trend of conductivity with increasing temperature up to 400°C; beyond this it behaves like an insulator. There was a stable conductivity while aging the films in ambient for a few days. This study revealed safe application temperature domain of CVO, and a clear correlation of electrical conductivity with the in-depth structural-compositional-morphological study. © Indian Academy of Sciences.