Structure and theoretical infrared spectra of OH defects in quartz

Jollands, Michael C.; Blanchard, Marc; Balan, Etienne

The infrared spectra of natural quartz, and synthetic quartz produced in conditions relevant to natural environments, generally contain some association of OH-stretching absorption bands at 3596, 3585, 3483, 3431, 3379 and 3313 cminline-formula−1, and/or a broad band at inline-formula∼ 3400 cminline-formula−1. In this study, a series of OH-bearing defects has been theoretically investigated from first principles within the density functional theory framework. The optimized structure, infrared spectroscopic properties and relative energy of defect configurations have been determined. Comparison with experimental observations enables the identification of atomic-scale configurations related to the experimentally observed OH-stretching bands. Consistent with previous interpretations, the results confirm the assignment of the bands at 3596 and 3483 cminline-formula−1 to OH defects associated with Binline-formula3+ substituting for inline-formulaSi4+ and to OH defects associated with inline-formulaLi+ cations located in the structural channels, respectively. They also confirm the assignment of the bands at 3313 and 3379 cminline-formula−1 to OH associated with the inline-formulaAl3+-for-inline-formulaSi4+ substitution and, by implication, the previously given interpretation of the 3431 cminline-formula−1 band in terms of Fermi resonance. The band at 3585 cminline-formula−1 does not appear to be related to a hydrogarnet-type defect, as has been proposed previously, but potentially corresponds to isolated inline-formulaOH groups bridging two Si atoms, where the charge compensation is ensured by a nonlocal mechanism.



Jollands, Michael C. / Blanchard, Marc / Balan, Etienne: Structure and theoretical infrared spectra of OH defects in quartz. 2020. Copernicus Publications.


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