SHOCK-INDUCED PHASE-TRANSITION OF SC2O3-TYPE, Y2O3-TYPE, SM2O3-TYPE, GD2O3-TYPE, IN2O3-TYPE COMPOUNDS

Sintered specimens of cubic Sc2O3-type structure (C-type, Ia3), Sc2O3, Y2O3, Sm2O3, and In2O3, and monoclinic Sm2O3-type structure (B-type, C2 m) Sm2O3, and powdered specimens of C-type Gd2O3 were shock-loaded to 2-50 GPa using flyer plates accelerated by a propellant gun. Recovered specimens were studied by X-ray powder diffraction analysis at room and high temperature. Y2O3 began to transform to the B-type structure above 12 GPa, and the transformation was completed at 20 GPa. Gd2O3 also transformed to the B-type structure, but residual temperature effects were observed in the yield and crystallinity of the high pressure phase. In2O3 transformed to the corundum structure (R3c) in the pressure range of 15-25 GPa, although the yield was very small. Shock-induced phase transition from the C-type to the B-type structure was inferred to proceed via hexagonal La2O3-type structure (A-type, P3m1), in comparison with static high pressure experiments. © 1990.