title: Contribution of molecular dynamics simulations and ab initio calculations to the interpretation of Mg K-edge experimental XANES in K(2)O-MgO-3SiO(2) glass.
abstract: The structural environment of Mg in a K-bearing silicate glass of composition K(2)MgSi(3)O(8) is investigated by x-ray absorption near-edge structure (XANES) spectroscopy at the Mg K-edge. XANES calculations are performed using a plane-wave electronic structure code, and a structural model obtained by classical molecular dynamics coupled to ab initio relaxation. Bond valence theory is used to validate plausible environments within the structural models. Comparison between the experimental and calculated spectra enables us to conclude that the Mg atoms are located in distorted tetrahedral sites. Site distortions are found to be correlated to the theoretical shift of the XANES edge position.
authors.affiliation: Synchrotron SOLEIL, l'Orme des Merisiers, France. Laboratoire Géomatériaux et Environnement, Université Paris EST, Champs sur Marne, Noisy-Champs cedex, France. nicolas.trcera@synchrotron-soleil.fr
authors.forename: Nicolas
authors.initials: N
authors.lastname: Trcera
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Rossano
authors.forename: Karim
authors.initials: K
authors.lastname: Madjer
authors.forename: Delphine
authors.initials: D
authors.lastname: Cabaret
mesh_terms: D005898:Glass / Q000737:chemistry*; D008274:Magnesium / Q000737:chemistry*; D008277:Magnesium Oxide / Q000737:chemistry; D056004:Molecular Dynamics Simulation; D010087:Oxides / Q000737:chemistry*; D017680:Potassium Compounds / Q000737:chemistry; D011789:Quantum Theory; D012822:Silicon Dioxide / Q000737:chemistry; D056928:X-Ray Absorption Spectroscopy
chemical_list: D010087:Oxides; D017680:Potassium Compounds; D008277:Magnesium Oxide; C068440:potassium oxide; D012822:Silicon Dioxide; D008274:Magnesium