DEVELOPMENT OF HYDROTHERMAL METHOD FOR GROWING SINGLE CRYSTALS OF HIGH PURITY BERYLLIUM OXIDE AND THE STUDY OF THE FEASIBILITY OF HYDROTHERMAL GROWTH OF SELECTED CRYSTALS.
Progress rept. no. 2, 16 Jan-15 Apr 67,
TEM-PRES RESEARCH INC STATE COLLEGE PA
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Beryllium oxide crystals weighing up to 1.3 grams have been grown hydrothermally with the nutrient temperature at 530 or - 5 C and the growth temperature at 500 or - 5 C. Four normal potassium hydroxide solution, which is also 0.06 normal with respect to LiOH, was used as hydrothermal solution. Growth occurred in the vapor phase above the hydroxide solution. The quality of the seeds used has a major effect on the quality of the crystals grown. X ray diffraction topographs confirmed that the crystals grown on 00.1 crystallographic direction seeds are more subject to mosaicity than those grown on either the 11.0 or 10.1 crystallographic direction seeds, but the 00.1 crystallographic direction growth is more tolerant to the presence of higher levels of LiOH. The topographs confirm that the best crystals were obtained when high quality 11.0 or 10.1 crystallographic direction seeds were overgrown in a solution which is also 0.06 normal with respect to LiOH. Infrared studies of selected crystals show that the bonded water can be extracted to below 70 ppm.