CORRELATION BETWEEN WATER-BATH TEMPERATURE, SOLUTION VISCOSITY AND OPTICAL PROPERTIES OF SOL–GEL DERIVED V2O5 THIN FILMS

Abstract

Thin films of V 2 O 5 were deposited on glass substrates by dip-coating technique using sol–gel route. The vanadium pentoxide sol was prepared by dissolving V 2 O 5 powder in H 2 O 2 solution. The solutions were kept in water bath and heated at five different temperatures for 30 min. The samples were annealed at 150°C for 60 min. The optical, structural, and morphological measurements were performed for characterization of samples. The effect of viscosity on optical constants (n, k, and Eg) of V 2 O 5 were studied. The indirect optical band gap energy of sol–gel V 2 O 5 thin films are about 2.33 eV and independent of viscosity within the error limits. The results show that the water-bath temperature strongly influences the viscosity of sol. The viscosity of sol was changed from 12.5 to 75 m Pa s. with increasing water-bath temperature from 50 to 90°C. The XRD measurements show that the structure of the V 2 O 5 films and powders is polycrystalline after annealing at 450°C. A correlation exists between the viscosity, morphology, and optical characteristics.