Experimental Investigation of Variable Emittance Material Based on (La, Sr)MnO3

Variable emittance radiators can be used in a thermal management system in space because their total emittance changes depending on the temperature of the system. When the temperature of the system decreased, the emittance also decreased so as to minimize the heat loss to the environment. In contrast, when the temperature of the system increased, the emittance also increased such that radiation cooling could occur. Thermochromic materials, whose emittance is a function of the temperature, are often used in variable emittance radiators because no additional parts are needed. In this study, we fabricated a variable-emittance coating by using a sol-gel method based on LSMO (La1-xSrxMnO3) and experimentally characterized the emittance change with respect to temperature. Furthermore, we also examined the stability of LSMO film in space environments by exposing it to extremely low pressure and temperature.