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Monoclinic structure and nonstoichiometry of 'KAlSiO4-O1'
Aleksandar Kremenović1, Biljana Lazic, Hannes Krüger
1Laboratory of Crystallography, Faculty of Mining and Geology, University of Belgrade, Đušina 7, 11000 Belgrade, Serbia. akremen@EUnet.rs
Abstract:
Crystals of KAlSiO4-O1 (potassium aluminium silicate) were synthesized using a flux method and analysed utilizing single-crystal X-ray diffraction and electron microprobe analysis. Both methods confirm that the crystals are nonstoichiometric according to K(1-x)Al(1-x)Si(1+x)O4 with x = 0.04 (1). KAlSiO4-O1 is closely related to the stuffed derivatives of tridymite, although the topology of the Si/Al-ordered framework is different. Six-membered rings of UUDDUD and UUUDDD (U = up and D = down; ratio 2:1) configurations are present in layers parallel to the ab plane. In contrast, the framework of tridymite exhibits UDUDUD rings. The crystals are affected by inversion, pseudo-orthorhombic and pseudo-hexagonal twinning.
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