Molecular dynamics (MD) simulations have been used to study the effect of Na ions on the structure properties of CaO–SiO_(2)–Na_(2)O melts. The short-range structure and medium-range structure of CaO–SiO_(2)–Na_(2)O in this study are consistent with existing data. The replacement of Ca~(2+) with Na~(+) in CaO–SiO_(2)–Na_(2)O melts has almost no effect on the degree of polymerization and distribution of bond angles of Si–O tetrahedron. From micro perspective, Na ions enhance the mobility of CaO–SiO_(2)–Na_(2)O melts by multiple ways. Firstly, the modification effect of Na~(+) on the melt network structure is weaker than that of Ca~(2+), the Si–O tetrahedron around Na~(+) is sparser than Ca~(2+), which is more conducive to ions movement. Secondly, the diffusion capacity of Na~(+) is much greater than other ions in CaO–SiO_(2)–Na_(2)O system, which the overall diffusion capacity of the system can be improved by adding more Na~(+). Thirdly, since Na~(+) has only one charge, there is no electrostatic restraint on the depolymerized tetrahedron which happened in multivalent charges such as Ca~(2+), so that the mobility of CaO–SiO_(2)–Na_(2)O is stronger than that of CaO–SiO_(2). The micro changes provide an explanation for the improvement of macro liquidity.
展开▼
