Phase equilibria investigations and thermodynamic modeling of the Eu2O3 - La2O3 and Eu2O3 - La2O3 - ZrO2 systems

The phase relationships of the ternary system Eu 2 O 3 - La 2 O 3 - ZrO 2 and binary Eu 2 O 3 - La 2 O 3 subsystem were experimentally and thermodynamically studied. Six three-phase fields and nine two-phase ones in the Eu 2 O 3 - La 2 O 3 - ZrO 2 system were investigated by X-ray diffraction, scanning electron microscopy and electron probe microanalysis with wavelength dispersive spectrometer at 1873 K and 1673 K. Nevertheless, there only existed a two-phase region in the Eu 2 O 3 - La 2 O 3 system in the temperature range from 1873 K to 1673 K. After that, the ternary mixing parameters for the system Eu 2 O 3 - La 2 O 3 - ZrO 2 including the binary interaction parameters in the Eu 2 O 3 - La 2 O 3 subsystem are optimized with the CALPHAD (CALculation of PHAse Diagrams) method, based on obtained experimental results. The high-temperature phase relationships and the special type of continuous solid solutions (La 2-x Eu x Zr 2 O 7 ) investigated in present work will contribute to exploring new materials with specific properties such as optical transparency.