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Structural relaxation around substitutional Cr (super 3+) in pyrope garnet

Amelie Juhin, Georges Calas, Delphine Cabaret, Laurence Galoisy and Jean-Louis Hazemann
Structural relaxation around substitutional Cr (super 3+) in pyrope garnet
American Mineralogist (May 2008) 93 (5-6): 800-805

Abstract

The structural environment of substitutional Cr (super 3+) ion in a natural pyrope Mg (sub 3) Al (sub 2) Si (sub 3) O (sub 12) has been investigated by Cr K-edge extended X-ray absorption fine structure (EXAFS) and X-ray absorption near edge structure (XANES) coupled with first-principles computations. The Cr-O distance is close to that in knorringite Mg (sub 3) Cr (sub 2) Si (sub 3) O (sub 12) , indicating a nearly full relaxation of the first neighbors. The local C (sub 3i) symmetry of the octahedral Y site is retained during Cr-Al substitution. The second and third shells of neighbors (Mg and Si) relax only partially. Site relaxation is accommodated by strain-induced bond buckling, with angular tilts of the Si-centered tetrahedra around the Cr-centered octahedron, and by a deformation of the Mg-centered dodecahedra.


ISSN: 0003-004X
EISSN: 1945-3027
Coden: AMMIAY
Serial Title: American Mineralogist
Serial Volume: 93
Serial Issue: 5-6
Title: Structural relaxation around substitutional Cr (super 3+) in pyrope garnet
Affiliation: Universite de Paris VII, Institut de Mineralogie et Physique des Milieux Condenses, Paris, France
Pages: 800-805
Published: 200805
Text Language: English
Publisher: Mineralogical Society of America, Washington, DC, United States
References: 39
Accession Number: 2008-091804
Categories: Mineralogy of silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 1 table
Secondary Affiliation: Universite Joseph Fourier, FRA, France
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, copyright, Mineralogical Society of America. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 200829
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