Three Crystalline Polymorphs of KFeSi04, Potassium Ferrisilicate

Janet Jonna Bentzen

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Orthorhombic α-KFeSi04 ( a =0.5478, b =0.9192, c =0.8580 nm), hexagonal β-KFeSiO4 (a =0.5309, c =0.8873 nm), and hexagonal γ-KFeSi04 (a =0.5319, c =0.8815 nm) were synthesized by devitrification of KFeSiO4 glass. Powder X-ray diffraction data are given for all three polymorphs. Alpha KFeSiO4, the high-temperature polymorph, melts congruently at 1197”±2”C. Mössbauer spectroscopy of the α phase indicates that Fe3+ occupies two tetrahedral sites in the lattice. Beta KFeSiO4, the low-temperature polymorph, and γ-KFeSiO4, a metastable polymorph, appear to be isomorphous with kalsilite, KAISiO4, and synthetic kaliophilite, KAISiO4, respectively, and it is proposed that β- and λ-KFeSiO4 are linked by Si-Fe order-disorder. Beta KFeSiO4 transforms slowly into α-KFeSi04 above 910°C but the transformation was not shown to be reversible in the present dry-heating experiments.

Original languageEnglish
JournalJournal of the American Ceramic Society
Issue number7
Pages (from-to)475-479
Publication statusPublished - 1983

Bibliographical note

Supported by the Danish Council for Scientific and Industrial Research


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