Establishment of the equilibrium phase diagrams in fluorite-related systems, ZrO₂-CeO₂ and SrF₂-LaF₃, by hydrothermal techniques

The equilibrium solidus phase diagrams in fluorite-related systems of ZrO₂-CeO₂ and SrF₂-LaF₃ are established by hydrothermal techniques in aqueous LiCl solution at below 1400°C and 750°C, respectively. The solid solutions of cubic, tetragonal and monoclinic phase are produced in the system ZrO₂-CeO₂. The tetragonal phase decomposes to monoclinic and cubic phase at the eutectoid temperature of 1050°C±50°C. The coexistent boundary of the tetragonal and cubic phase are about 18 and 70 mol% CeO₂, 16 and 80 mol% CeO₂, at 1400°C and 1200°C, respectively. The coexistent boundary of the monoclinic and cubic phase are about 1.5 and 88 mol% CeO₂, 1.5 and 98 mol% CeO₂, at 1000°C and 800°C, respectively. The solid solutions of cubic and hexagonal phases are produced in the system SrF₂-LaF₃. The coexistent boundaries of the cubic and hexagonal phases are about 47 and 94 mol% LaF₂, 47 and 96 mol% LaF₃, and 46 and 98 mol% LaF₃ at 750°C, 650°C and 500°C, respectively.