Pressure-induced structural change of CaO–Al2O3–SiO2 melt: Insight from molecular dynamics simulation

Abstract

Short-range and intermediate-range order structures as well as network structure of multicomponent oxide system (CaO–Al2O3–SiO2) under compression are investigated by molecular dynamics simulation (MDS). The short-range order structure is clarified via investigation of pair-radial distribution function (PRDF), coordination number distribution and topology of TOx (T = Al, Si; x = 3, 4, 5, 6) units. The intermediate-range order structure and -T-O- network structure are clarified through investigation of distribution of OMy(M = Si, Al, Ca; y = 2, 3, 4, 5) linkages and T-O-T bond angles between adjacent TOx-units. The distribution of bridging-oxygens (BO), non-bridging oxygens (NBO), and TOx-cluster size is also investigated to clarify the degree of polymerization of -T-O- network under compression. The pressure-induced structural change, incorporation mechanism of Ca2+ cations into -T-O- network, aluminum avoidance as well as the compositional and structural heterogeneities (micro-phase separation) in CaO–Al2O3–SiO2 melt are also discussed in detail.