Phase relations in the Gd2O3-Sm2O3-ZrO2 system: Experimental studies and thermodynamic modeling

Sm 2 Zr 2 O 7 and Gd 2 Zr 2 O 7 are two promising transparent ceramic materials with high density and effective atomic number. However, the phase diagram of Gd 2 O 3 -Sm 2 O 3 -ZrO 2 system has not been systematically studied. To determine the phase relationship of the ternary system Gd 2 O 3 -Sm 2 O 3 -ZrO 2 at 1600°C and 1400°C, a serious of ceramic samples were prepared and studied by X-ray diffraction, scanning electron microscope , and electron probe microanalysis . In the range of 66.6 mol.% ZrO 2 , the solubility of Gd 2 O 3 is 20–22.5 mol.% at 1600°C, and the binary intermediate phases Sm 2 Zr 2 O 7 and Gd 2 Zr 2 O 7 form a continuous solid solution at 1400°C. Using the experimental data as a foundation, thermodynamic modeling was performed using the approach. Based on the experimental data, the mixing parameters of fluorite , B and C phases were optimized, and thermodynamic modeling was performed using the CALPHAD (CALculation of PHAse Diagram) method. For the first time, a self-consistent database for Gd 2 O 3 -Sm 2 O 3 -ZrO 2 ternary system was established.