INVESTIGATION OF THE SOLUBILITY OF REFRACTORY OXIDES IN FUSED MELTS, THE DUGGER CRYSTAL GROWTH TECHNIQUE, AND FACTORS INFLUENCING THE GROWTH OF Be2GeO4.
Final rept. 22 Aug 66-21 Oct 68,
AMERICAN SCIENCE AND ENGINEERING INC CAMBRIDGE MASS
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Theoretical equations for predicting the solubility of refractory oxides in molten fluxes were developed. These equations relate oxide solubility to three thermodynamic parameters of the pure oxide the temperature of melting, the heat of melting, and the difference in the heat capacities of pure liquid and solid oxide. Effects of the flux upon the oxide solubility have been related to the partial molar heat of mixing of the oxide in the flux for simple systems and to generalized thermodynamic activity coefficients for complex systems. Equations for predicting the change of solubility with temperature were derived. Studies on the Dugger flux growth method did not proceed beyond the stage of experimental planning. A tentative phase diagram for the beryllium germanate system was experimentally determined. The implications of these phase relationships on the selection of crystal growth techniques for beryllium germanate have been discussed and a potential flux method of growth described. Results from the Program indicate that theoretical techniques can be usefully applied to predicting solubility relationships during the crystal growth of refractory oxides from fluxes the Dugger flux growth technique may be the first reported example of precipitation from an homogeneous flux solution crystal growth of beryllium germanate must be attempted by flux growth techniques. Author
- Ceramics, Refractories and Glass