The structure of molten alkali carbonates studied by neutron diffraction and ab initio calculations

Abstract

The total structure factors, S(Q), of pure molten and an equimolar mixture with , , were measured by neutron diffraction at 1013 K and 923 K, respectively. The results are generally consistent with the findings of previous MD simulations. The ion remains essentially unperturbed in the mixture. The real-space pair correlation functions are consistent with a close-packed, regular, planar, trigonal geometry for the ion in both and . There is some indication, also consistent with the findings of MD simulation, of a possible tightening of the local coordination of ions around in the presence of the larger, more weakly polarizing cation. Modelling the S(Q) data using structure factors calculated from monomer and dimer structures derived from ab initio quantum chemical calculations suggests that larger clusters are needed to realistically describe the melt local structure.