Structural relaxation around substitutional Cr3+ in pyrope garnet

Amélie Juhin; Georges Calas; Delphine Cabaret; Laurence Galoisy; Jean-Louis Hazemann

Structural relaxation around substitutional Cr3+ in pyrope garnet

Materials Science 2007-10-24 v1

Authors: Amélie Juhin , Georges Calas , Delphine Cabaret , Laurence Galoisy , Jean-Louis Hazemann

Abstract

The structural environment of substitutional Cr3+ ion in a natural pyrope Mg3Al2Si3O12 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 Mg3Cr2Si3O12, indicating a full relaxation of the first neighbors. The local C3i 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 radial deformation of the Mg-centered dodecahedra.

Cite

@article{arxiv.0710.4189,
  title  = {Structural relaxation around substitutional Cr3+ in pyrope garnet},
  author = {Amélie Juhin and Georges Calas and Delphine Cabaret and Laurence Galoisy and Jean-Louis Hazemann},
  journal= {arXiv preprint arXiv:0710.4189},
  year   = {2007}
}

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