Nucleation delay in the anorthite-diopside binary system: Models and experiments

Abstract

Nucleation delay was calculated for crystallization of anorthite (CaAl2Si2O8) and diopside (CaMgSi2O6) from melt, and for crystallization in 3 melts in the anorthite-diopside system using classical nucleation theory and values for equilibrium and transport properties from the literature. Calculations were compared to experiments in the literature and new experiments performed on diopside. Only one value, the activation energy of transport for diopside melt, was adjusted to fit the experiments. The activation energies, interfacial energies, and size of the structural unit of growth used for the end-member compositions were applied to calculate nucleation delays for three mixtures inside the binary. The calculated and experimental nucleation delays were within ~10x of each other, substantiating the use of classical nucleation theory to calculate nucleation delays in this system. Differences between measurements and calculations are probably due to uncertainties in equilibrium and transport properties of the system, particularly the activation energy for transport.