Phase Stability of Rare-Earth Sesquioxides - New Approach

Abstract

Based on low temperature synthesis it was stated that solid rare earth sesquioxides (RESOX) below 2000 °C belong to three structure types as function of temperature and metallic ionic radius. (I) Hexagonal for La2O3 and Nd2O3 with the highest metallic ionic radius, (II) Low Temperature (LT) cubic and High Temperature (HT) monoclinic for Sm2O3, Eu2O3 and Gd2O3 with medium metallic ionic radius, (III) cubic for Dy2O3, Y2O3, Ho2O3, Er2O3, Tm2O3, Yb2O3, Lu2O3 and Sc2O3 with low metallic ionic radius [1,2].