Phase Relations in the System CaO-Ta2O5-SiO2 |
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Authors: | D A REEVE NORMAN F H BRIGHT |
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Affiliation: | Mineral Sciences Division, Mines Branch, Department of Energy, Mines and Resources, Ottawa, Canada |
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Abstract: | The system CaO-Ta2O3-SiO2 was studied using a combination of hot-stage microscopy and the quenching technique. Primary crystallization fields were defined for the various calcium silicates, and for the calcium tantalates: CaO·2Ta2O5, CaO·Ta2O5, 2CaO·Ta2O5, and 4CaO·Ta2O5. A congruently melting ternary compound 10CaO·Ta2O5·6SiO2, isostructural with the mineral niocalite, is the only ternary phase in the system. A large twoliquid region extends across the system from the CaO-SiO2 binary to within 1 wt% of the Ta2O3-SiO2 binary but does not cut it, in marked contrast to the analogous CaO-Nb2O5-SiO2 system. Other somewhat unexpected differences were noted between these systems. |
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