Natural and synthetic leucites studied by solid state 29-Si and 27-Al NMR and 57-Fe Mossbauer spectroscopy |
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| Authors: | I W M Brown C M Cardile K J D MacKenzie M J Ryan R H Meinhold |
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| Institution: | 1. Chemistry Division, D.S.I.R., Private Bag, Petone, New Zealand
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| Abstract: | The 29-Si NMR spectra of natural and synthetic leucites (KAlSi2O6) are found to contain a number of resonances which are interpreted in terms of the known structure of low-temperature (tetragonal) leucite. Computer simulation of the spectra suggests that the most distorted tetrahedral lattice site T 1 contains a higher proportion of Al than the other two tetrahedral sites. The occurrence of some ordering of the tetrahedral Si and Al in leucite is confirmed by Mossbauer studies of synthetic iron-containing leucites, including the fully ferric end-member KFeSi2O6, in which the three tetrahedral sites can be distinguished. On replacement of about half this Fe by Al, the most distorted of these sites is lost from the spectrum, reflecting the preference of Al for this site. A linear relationship is found between the unit cell dimensions of all these leucites and their iron content. |
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