EXAFS and Molecular Dynamics combined study of CaO − FeO − 2SiO ₂ glass. New insight into site significance in silicate glasses

Abstract

A new and coherent view of the local environment of Fe2+ in silicate glasses is derived from a combined study by EXAFS and Molecular Dynamics simulation. Iron is located in distorted sites, whose geometry varies continuously from a tetrahedron to a triangular bipyramid. Iron polyhedra are apex-connected to the silicate network, while edge-linked to each other, matching with a random distribution of iron in the glass. Fe2+ does not have the significance of a network-forming element. Its local structure results from the freezing of dynamical exchange processes occurring in the liquid.