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Crystallization and Solubility of Zircon and Phenacite in Certain Molten Salts
Author(s) -
Ballman A. A.,
Laudise R. A.
Publication year - 1965
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1965.tb16047.x
Subject(s) - zircon , solubility , crystallization , alkali metal , chemistry , solvent , analytical chemistry (journal) , inorganic chemistry , materials science , mineralogy , geology , organic chemistry , geochemistry
Single crystals of zircon as large as 0.7 cm and phenacite as large as 1.5 cm were grown from molten alkali metal vanadates and molybdates. The best crystals were obtained by slow cooling melts of Na 2 O·3MoO 3 or Li 2 O·3MoO 3 saturated with zircon or phenacite from 1400° to 900°C at a rate of 2° per hour. Crystals grown on a seed by a thermal gradient process contained inclusions although rates up to 1 mm per day were obtained. Zircon crystals could be doped with Nd 3+ , Eu 3+ , Pr 2+ , Fe 3+ , Cr 3+ , and Mn 2+ . The rare earths fluoresced at their characteristic frequencies but no fluorescence was observed from the transition metal ions. Zircon crystals had the characteristic habit, being bounded by m (110) and p (111) faces. Phenacite had a rhombohe‐dral habit when grown above 1000° and crystallized as hexagonal needles below that temperature. The solubility of zircon in Na 2 O·3MoO 3 obeys the Van't Hoff equation with a heat of solution of 5.5 kcal per mole. The heat of solution of zircon and phenacite increased when V 2 O 5 was substituted for MoO 3 in the solvent, increased when NazO was substituted for Li 2 O, and increased further when K 2 O was substituted. The solubility was higher in solvents containing V 2 O 5 than in those containing Moo 3 . Solvent‐solute interactions were strongest when the solvents were strong Lewis acids since zircon and phenacite behave as bases.