Molecular Dynamics Analysis of Three-dimensional Anionic Structures of Molten Al_2O_3-Na_2O-SiO_2 System

摘要

For the molten Na_2O-SiO_2-Al_2O_3 system, the distributions of Al~(3+) ions in the various complex anions and the interconnected relations between the Si tetrahedra and Al tetrahedra consisted of the complex anions have been studied by molecular dynamics simulation and Raman spectroscopy. From the interconnected relations between Si and Al tetrahedra calculated by the molecular dynamics simulation, the abundance of complex anions was evaluated. Based on the abundance of these anions, the degree of polymerization in Na_2O-SiO_2-Al_2O_3 melts was found to be enhanced by the substitution of Al_2O_3 for SiO_2. The Raman spectroscopic band at around 520 cm~(-1) related to the three-dimensional network structure was found to develop with the replacement of SiO_2 by Al_2O_3 under the constant Na_2O content. Based on these results by molecular dynamics simulation and Raman spectroscopic measurements, it was confirmed that the Al~(3+) ion had a strong preference to enter the three-dimensional network structure.