Growth and annealing properties of Mg0.4Al2.4O4 crystal

Mg0.4Al2.4O4 single crystals with good optical quality were successfully grown by the Czochralski method. The transmission spectrum indicated that the absorption edge of the crystal was at 220 nm, while no apparent absorption peaks were found. The X-ray diffraction and DSC curve analysis showed that Mg0.4Al2.4O4 crystal was stable at room temperature. While after annealing in the air and hydrogen atmosphere at about 1200 °C, Mg0.4Al2.4O4 decomposed into Al2O3 and (MgO)0.4(Al2O3)x (0.4 < x < 1.2). The reaction mainly occurred on the crystal surface, barely inside.