SPECTROSCOPIC INVESTIGATION OF DEFECTS IN MAGNESIUM-ALUMINUM SPINEL CRYSTALS.

A study of crystals of magnesium-aluminum spinal, MgO:2Al//2O//3, grown by the Verneuil technique is reported. Excitation with ultraviolet light with subsequent measurement of the optical absorption spectrum EPR, the thermoluminescence was used to examine the defects and their properties. Induced absorption bands attributed to centers including both intrinsic defects and impurities, were observed at 390, 520, and 580 nm. Comparison of the spectroscopic characteristics of samples taken from the central and peripheral portions of a single crystal leads to the conclusion that the level of defects and the impurity concentration are large near the crystal face.