Prepared Method And Radiative Properties Of A Thrmochromic Thin Film Material

With the development of the small spacecraft, there is a growing demand to reduce its weight. Traditional thermal controller parts like MEMS shutters are difficult to meet the requirements because of their heavy quality and big volume. Perovskite-type manganese oxides is a material whose emittanec will change with the temperature. It can automatically adjust the radiation characteristics according to its own temperature level to reach the role of active intelligent temperature control. It will be widely used in the aerospace field.In this dissertation, perovskite-type manganese oxides Lal-xAxMnO3(A=Ca, Sr) is deposited on the YSZ, Si single crystal substates and quartz glass by RF magnetron sputtering system under different conditions, like sputter pressure, the oxygen partial pressure and sputter time. And the effects of thin film materials, substrates and sputtering conditions are analysised, which will affect the thin film deposition rate.Using the XRD, SEM, AFM and EDS to detect the phase structure, surface topography, RMS roughness and composition Elements properties, respectively. The effects of mainly factors such as thin film materials, substrates and sputtering conditions to the above-mentioned properties is presented. The XRD results show that all thin film samples are single phase perovskite structure. The SEM results show that thin film is smooth and dense, When its thickness is small. while its surface become rough with grooves and heave, When the thickness become large. And measurements of AFM consistent with measurements of SEM.Reflectivity spectra of thin film samples in different temperature are measured using the FT-IR and spectrophotometer. The emissivity of the samples are deduced by integral calculation from the experimental reflectivity data. The main factors to effect the radiation properties of surface are investigated. Experimental of experiment are reported as follow:For samples deposited on the YSZ, Si single crystal substates, their emittance will change with the sputter pressure, the oxygen partial pressure. When the thickness is below0.9μm, the emittance is almost invariant. While the thickness is up to0.9μm or more than0.9μm, the emittance will change with temperature. The emittance of La0.7Ca0.3MnO3、La0.8Sr0.2MnO3、 La0.7Ca0.165Sr0.35MnO3samlpes deposited on the YSZ are similar to each other, while La0.7Ca0.3MnO3sample’ emittance Vary widely. But for La0.7Ca0.3MnO3、La0.8Sr0.2MnO3、 La0.7Ca0.3MnO3samlpes deposited on the Si, the emitttance reduce in turn. The smples’ emittance don’t change with temperature, which deposited on the quartz glass. If Ag or Al are chosed as transition layer between the Perovskite-type thin film and quartz glass, their emittance can change with temperature. When the Al is chosed as transition layer, variation range of emission increase with the pressure increases. And the emission decreases with at the same pressure.