OPTICAL-PROPERTIES OF CAAL2S4 AND MGAL2S4 SINGLE-CRYSTALS

CaAl2S4 and MgAl2S4 single crystals were grown by the chemical transpo rt reaction method. They crystallized into an orthorhombic structure, and their optical energy gaps were found to be 4.63 eV for the CaAl2S4 single crystal and 4.14 eV for the MgAl2S4 single crystal at 300 K. A blue emission with a peak at 387 nm and a green emission with a peak at 515 nm appeared in the CaAl2S4 single crystal at 10 K. A blue emiss ion with a peak at 432 nm appeared in the MgAl2S4 single crystal at 10 K.