Post-annealing effect on transparent Mg-Zn aluminate solid solutions fabricated by spark plasma sintering

In MgAl2O4 (Mg aluminate) fabricated by pressure sintering, carbon contamination, oxygen vacancy, and other defects exist and cannot be completely removed even after post-annealing. ZnAl2O4 (Zn aluminate) has the same crystallographic structure as Mg aluminate and excellent light transmission by post-annealing. In this study, the transmission of (Mg1-xZnx)Al2O4 spinel, which is a solid solution between Mg aluminate and Zn aluminate, was investigated. After post-annealing, the transmission of (Mg1-xZnx)Al2O4 spine] was higher than Zn aluminate and Mg aluminate, which means that the absorption center disappeared. Besides, the real in-line transmission is improved by up to 30% by post-annealing, which is related to the driving force to increase the configurational entropy and form a more stable solid solution phase. In solid solution spine], as the Zn content increases, the optical properties can be improved by post-annealing, but the mechanical properties are slightly decreased.