Abstract: Phase equilibria studies in the system BaB2O4|BaTa2O6 disclosed three modifications of the latter compound: a low temperature modification isomorphous with orthorhombic BaNb2O6 which forms below about 1150°C, a tetragonal modification having the potassium tungsten bronze structure which forms between about 1150°C and 1300°C, and a hexagonal modification stable from 1300°C to its melting point at about 1850–1900°C. Crystals of the orthorhombic and hexagonal modifications have been grown from this system by the slow-cooling technique. The tetragonal form could only be obtained as a very fine precipitate. Attempts were made to grow the hexagonal modification from the melt using the Czochralski technique; it was found that not only the hexagonal, but the orthorhombic and tetragonal forms as well, could be grown in this fashion. The phase transformation of crystal fragments was investigated. Only transformations from the orthorhombic and tetragonal forms to the hexagonal form were observed to occur in times less than 100 hours in the appropriate temperature ranges.
Publication Year: 1967
Publication Date: 1967-05-01
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 42
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