Nanometer thick thermochromic film based on K-doped manganite oxide prepared by magnetron sputtering

For seeking a lightweight thermochromic film acting as a smart radiation device in thermal control system for spacecraft, the (La,Ca,K)MnO3±δ films with different thicknesses were deposited on Si(100) substrate by magnetron sputtering method with a target which was synthesized by a sol-gel method. The crystal structure and micro-morphology of these films are investigated. The results reveal that all films form an orthorhombic perovskite structure, and it undergoes a Volmer-Weber growth mode with the increased thickness. Temperature-dependent infrared reflectivity and emittance are investigated. Spectra data indicate that reflectivity of all films has a decreased trend with increasing temperature. In the temperature range of 173-373 K, the K-doped thermochromic films show a large emittance increment near 0.36 with film thickness only 321 nm. All of these results show that the thermochromic film has a great potential to be applied to a more lightweight and cost-effective thermal control device in spacecraft with an excellent radiation performance.