CZOCHRALSKI GROWTH OF LAALO3

Good quality spinel single crystals both undoped and Cr(+3)-doped were grown via a modified Czochralski process similar to that utilized for the growth of LaAlO3. Spectroscopic studies of Cr(+3)-doped samples indicate a half-intensity line width at room temperature of about 50A for the principal component centered around 6876A. Fluorescent lifetimes of 12 and 11 milliseconds were measured at -183C and 24C respectively for this component. Several much narrower bands of variable intensity depending upon the radiation history of the specimen were also observed. The absorption spectrum of Cr(+3)-MgAl2O4 resembles that of ruby, but the absorption coefficients are significantly lower. Lasing tests carried out with fabricated rods of Cr-doped spinel have thus far not yielded any detectable laser output. Lasing attempts with Cr:LaAlO3 rods fabricated from crystals grown during the course of this program have likewise not yet proved successful. (Author) See also AD-635 920.