GROWTH OF RUBY CRYSTALS FROM SOLUTION.
Semiannual technical summary rept. no. 5 (Final), 1 Jan-30 Apr 64,
BATTELLE MEMORIAL INST COLUMBUS OH
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Some investigation has been made of various solvent compositions in the LiF-AlF3 system. It has been noted qualitatively that neither pure LiF nor pure AlF3 will dessolve appreciable concentrations of alumina. As the AlF3 concentration in the solvent is increased in the range 2LiF.AlF3 to 5.7LiF.AlF3, the solubility of alumina appears to increase. However, there also is an accompany ing increase in vapor pressure, and hence loss by vapor transport, of the solvent. No significant advantage for selecting a solvent composition other than the Li3AlF6 composition was apparent. The main obstacle which was encountered to the growth of large crystals was the apparent c ssation of crystal growth following a period of crystallization at a reasonably high rate at the beginning of each crystal-growth run. A number of factors were identified and considered as potential causes of the change in over-all growth rate. These were 1 the effect of changing crystal morphology, 2 solute-solvent side reaction to yield a stable mixed phase, 3 the rate of mass transport, and 4 the kinetics of the solution-precipitation reaction. To investigate the influence of these factors, conditions were altered in a planned series of growth experiments. Seed crystal orientation the concentration, particle size, and type of the alumina or ruby feed stock the degree of agitation of the solution system geometry and solvent composition were varied. Author