Thermal behaviour of vibrational phonons and hydroxyls of muscovite in dehydroxylation: In situ high temperature infrared spectroscopic investigations

Zhang, M. and Redfern, S. A. T. and Salje, E. K. H. and Carpenter, M. A. and Hayward, C. (2010) Thermal behaviour of vibrational phonons and hydroxyls of muscovite in dehydroxylation: In situ high temperature infrared spectroscopic investigations. American Mineralogist, 95 (10). pp. 1444-1457. DOI 10.2138/am.2010.3472

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Abstract

Temperature dependencies and thermal dynamical behavior of vibrational phonons related to different bonds/motions (e.g., K-O, Si-O, and Al-O) and O-H stretching, bending, and combinations bands, as well as those of NH4 ions, of muscovite have been investigated in detail at high temperatures using in situ infrared spectroscopy. Phonon modes of muscovite show a complex response to heating and dehydroxylation. The mode Grüneisen parameters of muscovite are largest for low-frequency bands and some bands have negative values. Approaching dehydroxylation, bands associated with K-O stretching, Al-OH bending, and Al-O vibrations exhibit significant variations, indicating modifications of local configurations related to these ions. The O-H stretching feature near 3627 cm–1 shows a change in temperature dependence of the peak position near or during dehydroxylation, and this is attributed to a dramatic loss of OH and changes in local environments. The infrared spectroscopic analyses carried out in situ or on quenched samples do not record the characteristic bands of dehydroxylation-induced H2O and these findings suggest that H2O is unlikely to be the principal diffusing species. The results suggest that de-ammoniation or loss of NH4 in muscovite takes place at temperatures near dehydroxylation.

Item Type: Article
Uncontrolled Keywords: 2010AREP; IA61;
Subjects: 03 - Mineral Sciences
Divisions: 03 - Mineral Sciences
Journal or Publication Title: American Mineralogist
Volume: 95
Page Range: pp. 1444-1457
Identification Number: 10.2138/am.2010.3472
Depositing User: Sarah Humbert
Date Deposited: 14 Jul 2010 16:55
Last Modified: 23 Jul 2013 09:57
URI: http://eprints.esc.cam.ac.uk/id/eprint/1457

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