Thermophysical Properties of Metal-Insulation Transition Materials as a Functional Thermal Control Device for Microsatellite
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In recent times, the functions of microsatellites have become very complex. As the functions increase, thermal design of them have become important due to the heat generated by the mounted equipment. Therefore, Smart Radiation Device (SRD) using a change in emittance due to Metal-Insulated Transition (MIT) such as perovskite-type Mn oxide, VO2 has gained attention as a thermal control device suitable for a micro satellite. Various studies have only focused on the emissivity of those materials. This study focuses on the not only emissivity and but also specific heat and thermal conductivity and proposes a new thermal control device. The concept of a new thermal control device is composed of a single material which have 3 functions including variable emittance, variable thermal conductivity and heat storage. To evaluate the proposed device, it is necessary to elucidate the relation between the transition property and changes in thermophysical properties. There are no researches which measured 3 thermophysical properties using the same specimen. In this study, the properties of same specimen of perovskite-type La1-xAxMnO3 (A = Sr(LSMO), Pb(LPMO)) and VO2 which have MIT were measured and investigated the relationship between changes in the properties and transition characteristic of the material. Perovskite-type materials were fabricated by solution-combustion method and all of Bulk samples were sintered. Temperature dependence of specific heat, thermal conductivity, emittance of the same specimen were measured by Differential Scanning Calorimetry (DSC), A Laser-Spot Periodic Heating Method and Calorimetry Method respectively. From the results, the lambda-shape peak in specific heat of LSMO, LPMO and a sharp peak in one of VO2 were found at the transition point. As the metal phase began, a decreases in emittance and increase in thermal conductivity were confirmed in all the materials. These characteristics is in accordance with what were predicted from characteristics of transition.