Variable emissivity property of magnetron sputtering thermochromic film

Thermochromic films are prepared on the substrate of yttria stabilized zirconia by radio frequency magnetron sputtering technique. Crystalline structure and surface morphology are characterized. Characterization result shows that the films are of perovskite structure exhibiting a dense and smooth surface morphology. Composition analysis is performed and the result indicated that the element composition of films can be adjusted to close its stoichiometric ratio by controlling the oxygen flow ratio. Temperature-dependent reflectivity and emissivity are studied. Reflectivity spectra show that the film undergoes a transition from a metallic state to a non-metallic state with increasing temperature. Emissivity of the films is large above the transition temperature and it decreases sharply below the temperature. The emissivity increment at 97-373 K can approach 0.39 by controlling sputtering pressure, working gas and film thickness.