A Microscopic View of Mass Transport in Silicate Melts by Quasielastic Neutron Scattering and Molecular Dynamics Simulations

Abstract

The application of quasielastic neutron scattering and molecular dynamics simulation to the study of mass transport in silicate melts is outlined. It is shown how the knowledge of atomic dynamics and structure reveals the mechanisms of mass transport. Peculiar properties of atomic diffusion and viscous flow behaviour as a function of melt composition are discussed in terms of the formation of alkali diffusion channels in the static structure. This non-homogeneous distribution of alkali ions in a disrupted tetrahedral Si-O network is investigated in binary lithium, sodium and potassium silicate melts and in ternary sodium aluminosilicates and sodium ironsilicates representing the main compositions of natural volcanic rocks.