We have developed a variable-emittance radiator device, made of thin, and fight ceramic tiles, for thermal control applications on spacecraft. The ceramic material used is La1-xSrMnO3 with a perovskite structure, which shows a phase transition from a ferromagnetic metal with a low thermal emittance of 0.35 to a paramagnetic insulator with a high thermal emittance of 0.75 at around 300K. This device automatically controls the temperature of a spacecraft without requiring electrical or mechanical instruments. The fabrication process for the ceramic tiles was designed to reduce production costs and weight. The tiles are less than 70-microns thick and weigh 450g/m(2). Both a conventional type of ceramic wafer and a thick film type were developed and tested for their durability under various environmental and radiation conditions. The results showed no degradation. These variable emittance radiators made of ceramic tiles have been used for the MUSES-C spacecraft designed to probe asteroids, and are also scheduled to be used for the INDEX spacecraft designed to observe the earth.