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Article Dans Une Revue European Journal of Mineralogy Année : 2021

First-principles modeling of the infrared spectrum of Fe- and Al-bearing lizardite

Résumé

Abstract. The theoretical vibrational properties of a series of Fe- and Al-bearing lizardite models have been determined at the density functional theory level. Each periodic model displays a single cationic impurity substituted at an octahedral or tetrahedral site of a supercell of lizardite (Mg3Si2O5(OH)4) containing 162 atoms. The isovalent Fe2+ for Mg2+ substitution has been considered, as well as the heterovalent substitution of Fe3+ or Al3+ for Mg2+ or Si4+. Comparison of the theoretical absorption spectra with previously reported experimental spectra of natural and laboratory-grown lizardite samples allows us to propose an interpretation for most of the observed bands. Although the identification of specific bands related to octahedral Fe2+ in FTIR spectra is challenging, broad bands at 3584 and 3566 cm−1 reflect the occurrence of octahedral Al3+ and Fe3+, respectively, in the natural samples. These broad bands likely overlap with potential contribution related to tetrahedral Al3+. It is suggested that the modification of the H-bonding pattern related to the incorporation of trivalent ions at tetrahedral sites has an overall broadening effect on the interlayer-OH stretching bands of lizardite.

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Minéralogie
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Origine : Publication financée par une institution

Dates et versions

hal-03424587 , version 1 (10-11-2021)

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Etienne Balan, Emmanuel Fritsch, Guillaume Radtke, Lorenzo Paulatto, Farid Juillot, et al.. First-principles modeling of the infrared spectrum of Fe- and Al-bearing lizardite. European Journal of Mineralogy, 2021, 33 (5), pp.647-657. ⟨10.5194/ejm-33-647-2021⟩. ⟨hal-03424587⟩
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