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Theoretical infrared spectrum of partially protonated cationic vacancies in forsterite

Celine Crepisson, Helene Bureau, Marc Blanchard, Jannick Ingrin and Etienne Balan
Theoretical infrared spectrum of partially protonated cationic vacancies in forsterite
European Journal of Mineralogy (February 2014) 26 (2): 203-210

Abstract

Hydroxyl defects in pure forsterite are usually ascribed to incorporation of protons fully compensating the electrostatic charge of cationic vacancies. However, partially compensated vacancies have been predicted from theoretical considerations. Here, we theoretically determine the structural, vibrational and infrared spectroscopic properties of partially protonated cationic vacancies in forsterite using a first-principles theoretical modeling approach. The results show that the partial protonation of Si vacancies strongly modifies their spectroscopic properties with respect to those of the fully protonated (4H) (super x) (sub Si) defect, leading to a significant downshift of at least one of the OH-stretching absorption bands. Comparison with experimental observations shows that such defects are unlikely to significantly contribute to the speciation of OH groups in pure synthetic forsterite samples. A partial protonation of Mg vacancies has a weak effect on the spectroscopic properties of OH groups, compared with those of the fully protonated defect, making it difficult to assess their occurrence from spectroscopic observations only.


ISSN: 0935-1221
EISSN: 1617-4011
Serial Title: European Journal of Mineralogy
Serial Volume: 26
Serial Issue: 2
Title: Theoretical infrared spectrum of partially protonated cationic vacancies in forsterite
Affiliation: Universite Paris VI, Sorbonne Universites, Institut de Mineralogie et Physique des Milieux Condenses, Paris, France
Pages: 203-210
Published: 201402
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Germany
References: 32
Accession Number: 2014-028699
Categories: Mineralogy of silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 1 table
Secondary Affiliation: Universite Lille 1, FRA, France
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, copyright, Schweizerbart'sche Verlagsbuchhandlung. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201418
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