Czochralski growth of rare earth gallium garnets

Abstract

Single crystals of Gd 3Ga 5O 12, Nd 3Ga 5O 12 and other rare earth gallium garnets have been grown by the Czochralski technique using iridium crucibles as the container. It has been found that the optimum growth rate for these materials is about 6mm/hr with a rotation rate of 45 RPM. The rotation rate has a marked influence on the crystal quality. The high rotation rate is necessary to eliminate the “core” due to the formation of the (211) facets on the growth interface. In addition to the pure rare earth gallium garnets, solid solution single crystals of Gd 3Ga 5O 12-Dy 3Ga 5O 12, Sm 3Ga 5O 12-Nd 3Ga 5O 12 and Sm 3Ga 5O 12-Gd 3 Ga 5O 12 have been grown. In all cases, the distribution coefficient for the solid solutions is close to one, so that only very small lattice parameter variations were observed in the crystal. Constitutional supercooling during growth was a serious problem in all solid solutions considered, but adjustment of the crystal growth rate has resulted in considerable improvement of the solid solution single crystals.