THERMOCHROMIC V1-XNBXO2 SOL-GEL THIN-FILMS

Pure and doped vanadium dioxide was synthesised from alkoxide precurso rs. VO(OAmt)(3) solutions are spin-coated onto fused silica substrates and transformed into crystalline VO2 by a thermal treatment under a r educing atmosphere (Ar-H-2 5%). Crystalline thin films about 0.2 mu m in thickness are obtained around 500 degrees C. Doped VO2 films are si mply prepared by mixing precursor solutions. All these V1-xNbxO2 films (x < 0.8) exhibit the typical metal-insulator transition accompanied by an abrupt change in electrical and optical properties. V1-xNbxO2 th in films exhibit a high infrared reflectivity in the metallic state an d could be used as optical switches.