Phase stability study of the pseudobinary system Gd2O3-Nd2O3 (T <= 1350 degrees C)

The phase stability of the system Gd2O3-Nd2O3 up to 1350°C was studied. Mixed oxides were synthesized by coprecipitation of mixed oxalates. Depending on the thermal treatment, three possible structures of the oxides, namely the A (hexagonal, P63/mmm), B (monoclinic, C2/m) and C (cubic, Ia3) forms, were obtained. Below 1300°C the system Gd2O3-Nd2O3 shows three monophasic (A, B and C phase) and three biphasic regions (A+B, B+C and A+C phase). Below 550°C the C phase is stable over the whole composition range. A validation procedure for the existence of the C phase in pure Nd2O3 was also set up.