Low-temperature infrared spectroscopic study of OH-stretching modes in kaolinite and dickite

Balan, Etienne and Delattre, Simon and Guillaumet, Maxime and Salje, Ekhard K. H. (2010) Low-temperature infrared spectroscopic study of OH-stretching modes in kaolinite and dickite. American Mineralogist, 95 (8-9). 1257 -1266. DOI https://doi.org/10.2138/am.2010.3447

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The powder-transmission infrared spectra of OH-stretching modes in well-ordered samples of kaolinite and dickite are recorded from 270 to 10 K. Effective medium modeling of the kaolinite spectrum confirms the coupled motion of non-equivalent OH groups in the inter-layer OH-stretching modes. A full assignment of OH-stretching bands in dickite is proposed. In particular, the band observed at 3685 cm−1 in room-temperature spectra is attributed to a kaolinite-like defect, whereas that at 3706 cm−1 is related to OH3 groups of the dickite structure. The changes in phonon frequency and line shape are analyzed as a function of temperature. The results evidence the quasi-harmonic nature of the OH-stretching modes in kaolinite-group minerals. Coupling of OH-stretching modes to each other can be related to the macroscopic electrostatic properties of the composite medium, made of mineral particles and KBr matrix, and not to microscopic anharmonic mechanisms. The low saturation temperatures of vibrational frequencies and linewidths indicate that the OH-stretching modes probe the average thermal bath of the crystal, without coupling to a specific decay channel.

Item Type: Article
Uncontrolled Keywords: 2010AREP (add); IA60
Subjects: 03 - Mineral Sciences
Divisions: 03 - Mineral Sciences
Journal or Publication Title: American Mineralogist
Volume: 95
Page Range: 1257 -1266
Identification Number: https://doi.org/10.2138/am.2010.3447
Depositing User: Sarah Humbert
Date Deposited: 08 Feb 2012 12:11
Last Modified: 23 Jul 2013 10:03
URI: http://eprints.esc.cam.ac.uk/id/eprint/2380

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