The behavior of Cr(OH)3-Ca(OH)2 system and CaCrO4 in H2 atmosphere was studied. In Cr(OH)3-Ca(OH)2 system, α was produced at 580°C, at which the crystallization of Cr(OH)3 occurs; however, in Cr2O3-Ca(OH)2 system, it was produced after calcined above 800°C. It was not evident whether α, having an empirical formula of Ca3Cr10O18, is a simple substance or not. Alpha (α) was produced by the calcination of CaCrO4 at 510°C in the reducing atmosphere, and it was decomposed into CaCrO4 and Cr2O3 when calcined at 470°C in the air.
