Determination of Fe~(3+) sites in a NaFeSi_2O_6 glass by neutron diffraction with isotopic substitution coupled with numerical simulation

摘要

Isotopic substitution in neutron diffraction combined with empirical potential structure refinement simulations has been employed to probe the sites occupied by Fe~(3+) and Fe~(2+) in a NaFeSi_2O_6 glass. This study reveals the presence of two populations of Fe~(3+) sites. 95% of Fe~(3+) is in tetrahedral sites (d_(Fe~(3+)-O)= 1.866 ± 0.001 A), as the remainder ferric iron and ferrous iron (～20% of total Fe) are five coordinated.