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. 3, 16 Apr-15 Jul 67,
TEM-PRES RESEARCH INC STATE COLLEGE PA
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The factors which affect the quality of hydrothermally grown BeO single crystals were investigated. These are conveniently divided into seed and environment related factors. The important seed-related factors are orientation, polarity, and the presence of defects. The environment related factors are temperature stability of the system, the position of the crystal in the autoclave, and the presence of impurities. Defects present in the seeds are preferred nucleation sites and hinder migration of the nuclei on the growing face. This is particularly important on the 00.1 plane. It was also observed that the 00.1 acts as a twin plane. These observations suggest that high quality 10.1 oriented seeds are the best. The proper design of the equipment and the use of high purity reagents can minimize the effects of the environment related factors. It is also necessary that the seeds be placed away from the walls of the autoclave. The solubility of calcite in the lithium chloride and lithium carbonate solutions were studied, along with other mineralizers. The lithium salts were preferred, but difficulty was experienced in removing the calcite crystals from the lithium carbonate matrix. Author