Molecular Dynamics Study of the Structure of Calcium Aluminate Melts

The microstructure of high- temperature xCaO-(1-x)Al2O3 melts was studied by the molecular dynamics simulation. By comparing the positions of first peaks of partial radial distribution functions between Al and O, Ca and O, O and O, and the coordination numbers of Al and Ca with the corresponding experimental data of X-ray diffraction and neutron scattering, which agree very well with each other, the simulation is proved very successful. Based on the verification, it was found that Al playes the roll of network former in the calcium aluminate melt. That's to say, the average coordination number of Al is 4 and tetrahedron is the main structural unit in calcium aluminate just as the action of Si in silicate melts. In the meantime, the distribution of 5 kinds of tetrahedrons Qi was counted and then the regulation of the changing microstructure of calcium aluminate melt following with the composition was analyzed. With the analysis of the number of next nearest neighbor around the centering atom Al and the examination of the snapshot, 3-coordinated oxygen and charge-balanced bridging oxygen were found to be the explanations of the phenomena of redundant charge and location of the cation Ca2+.