title: Structure of molten CaSiO3: neutron diffraction isotope substitution with aerodynamic levitation and molecular dynamics study.
abstract: We have performed neutron diffraction isotopic substitution experiments on aerodynamically levitated droplets of CaSiO(3), to directly extract intermediate and local structural information on the Ca environment. The results show a substantial broadening of the first Ca-O peak in the pair distribution function of the melt compared to the glass, which comprises primarily of 6- and 7-fold coordinated Ca-polyhedra. The broadening can be explained by a redistribution of Ca-O bond lengths, especially toward longer distances in the liquid. The first order neutron difference function provides a test of recent molecular dynamics simulations and supports the MD model which contains short chains or channels of edge shared Ca-octahedra in the liquid state. It is suggested that the polymerization of Ca-polyhedra is responsible for the fragile viscosity behavior of the melt and the glass forming ability in CaSiO(3).
authors.affiliation: Mineral Physics Institute & Department of Geosciences, Stony Brook University, Stony Brook, New York 11794-2100, USA.
authors.forename: L B
authors.initials: LB
authors.lastname: Skinner
authors.forename: C J
authors.initials: CJ
authors.lastname: Benmore
authors.forename: J K R
authors.initials: JK
authors.lastname: Weber
authors.forename: S
authors.initials: S
authors.lastname: Tumber
authors.forename: L
authors.initials: L
authors.lastname: Lazareva
authors.forename: J
authors.initials: J
authors.lastname: Neuefeind
authors.forename: L
authors.initials: L
authors.lastname: Santodonato
authors.forename: J
authors.initials: J
authors.lastname: Du
authors.forename: J B
authors.initials: JB
authors.lastname: Parise