Microstructure and high-temperature phase stability of Co-precipitation (Mg0.2Al0.2Ce0.2Y0.2Zr0.2)O1.6 high entropy ceramics powders

(Mg0.2Al0.2Ce0.2Y0.2Zr0.2)O1.6 high entropy ceramics powders have been prepared by co-precipitation method with two calcination temperatures (1000 degrees C and 1200 degrees C). The microstructure, phase composition and phase stability after repeated calcination at 1400 degrees C with various times of the powders have been investigated. The powder calcined at 1200 degrees C has the better crystallinity and the stronger diffraction peak of t-ZrO2 phase at room temperature. The existence of Ce4+ and Y3+ with large radius in the ZrO2 lattice can enhance the tetragonality of the powders. The Mg2+ and Al3+ with small radii can exist in the lattice gap of ZrO2 or replace the position of Zr4+, causing lattice contraction, offsetting the lattice expansion which caused by Ce4+ and Y3+, and reducing the negative effects induced by the large ion doping. Thus, (Mg0.2Al0.2Ce0.2Y0.2Zr0.2)O1.6 has a good phase stability after repeated calcination at 1400 degrees C for 80h.