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Three Crystalline Polymorphs of KFeSiO 4 , Potassium Ferrisilicate
Author(s) -
BENTZEN JANET J.
Publication year - 1983
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.1151-2916.1983.tb10584.x
Subject(s) - devitrification , orthorhombic crystal system , crystallography , mössbauer spectroscopy , materials science , powder diffraction , metastability , hexagonal crystal system , polymorphism (computer science) , phase (matter) , chemistry , crystal structure , crystallization , biochemistry , organic chemistry , genotype , gene
Orthorhombic α‐KFeSiO 4 ( a =0.5478, b =0.9192, c =0.8580 nm), hexagonal β‐KFeSiO 4 ( a =0.5309, c =0.8873 nm), and hexagonal γ‐KFeSiO 4 ( a =0.5319, c =0.8815 nm) were synthesized by devitrification of KFeSiO 4 glass. Powder X‐ray diffraction data are given for all three polymorphs. Alpha KFeSiO 4 , the high‐temperature polymorph, melts congruently at 1197°± 2°C. Mössbauer spectroscopy of the α phase indicates that Fe 3+ occupies two tetrahedral sites in the lattice. Beta KFeSiO 4 , the low‐temperature polymorph, and γ‐KFeSiO 4 , a metastable polymorph, appear to be isomorphous with kalsilite, KAISiO 4 , and synthetic kaliophilite, KAISiO 4 , respectively, and it is proposed that β‐ and γ ‐KFeSiO 4 are linked by Si‐Fe order‐disorder. Beta KFeSiO 4 transforms slowly into α ‐KFeSi0 4 above 910°C but the transformation was not shown to be reversible in the present dry‐heating experiments.