Optical and Phase Transition Properties of Ti<sub><em>x</em></sub>V<sub>1-<em>x</em></sub>O<sub>2</sub> Thin Films

TixV1-xO2 (0 <= x <= 1) thin films with different molar ratios of V/Ti were prepared on c-plane sapphire (0001) substrates by radio frequency magnetron sputtering. The microstructure and optical properties of the thin films were determined by X-ray diffraction (XRD), Raman spectroscopy, and UV-visible-near infrared (UV-Vis-NIR) spectroscopy. The width of the optical band gap was calculated and the integrated solar transmittance of the films was characterized. As the content of titanium was increased, infrared regulation and thermal hysteresis were gradually reduced until they disappeared. The results show that the band gap of the thin films broadens as the content of titanium increases, causing the optical absorption edge to exhibit a blue shift. Conversely, the band gap narrows as the proportion of vanadium is increased, which causes a red shift of the optical absorption edge.