Phase Equilibria in Systems Involving the Rare Earth Oxides. Part III. The Eu(2)O(3)−In(2)O(3) System

The equilibrium phase diagram was determined for the Eu(2)O(3)−In(2)O(3) system. An induction furnace, having an iridium crucible as the heating element (susceptor), was used to establish the solidus and liquidus curves. The 1:1 composition melts congruently at 1745 ± 10 °C. Melting point relations suggest that the 1:1 composition is a compound with solid solution extending both to 31 mole percent In(2)O(3) and 71 mole percent In(2)O(3). The compound is pseudohexagonal with a(H) = 3.69 A and c(H) = 12.38 A. Isostructural phases also occur in the 1:1 mixtures of both Gd(2)O(3) and Dy(2)O(3) with In(2)O(3). The melting points of Eu(2)O(3) and In(2)O(3) were determined to be 2,240 ± 10 °C and 1910 ± 10 °C respectively. A eutectic occurs in the Eu(2)O(3)−In(2)O(3) system at 1,730 °C and about 73 mole percent In(2)O(3). The indicated uncertainties in the melting points are conservative estimates of the overall inaccuracies of temperature measurement.