Effects of impurities, dopants, and atmosphere on the growth of Cr-doped gadolinium scandium gallium garnet.

Crystals of Cr-doped gadolinium scandium gallium garnet were grown by the Czochralski technique. The concentrations of divalent and tetravalent dopants and the oxygen partial pressure in the growth atmosphere were varied to examine their effect on growth morphology and optical absorption in the crystal. The complexing of divalent and tetravalent ions in the melt was modeled to explain the results. The best doping scheme was to add an excess of Mg sup (2+) to prevent interface instability and spiral morphology, combined with a buffering concentration of Ti sup (4+) to limit the amount of Cr sup (4+) that can enter the crystal and contribute to absorption at 1 micrometer.