Effect of TiO₂ Content on the Structure of CaO–SiO₂–TiO₂ System by Molecular Dynamics Simulation

抄録

The change of structure in the ternary system CaO–SiO₂–TiO₂ with TiO₂ varying from 0 to 25% mole fraction at a fixed basicity of 0.8 was investigated by means of molecular dynamics simulation. The present simulation demonstrates that most Si is coordinated with 4 O within a tetrahedron while the majority of Ti with 6 O in an octahedron. With the addition of TiO₂, the coordination number for Si (CN_Si–O) changes from 4.12 to 4.03, while the CN_Ti–O varies from 5.83 to 5.52. The fraction of bridging oxygen (Si–O–Si) decreases resulting in the depolymerization of silicate structure and the Si–O–Ca is gradually replaced by Si–O–Ti with increasing TiO₂ fraction. Two [TiO₆] octahedrons are connected by two ways with the angles of Ti–O–Ti equaling to 100° and 140°, and the fraction of them are almost the same for sample with 10 mol-% TiO₂ addition. The variation of network connectivity Qⁿ of Si also agrees with the above conclusion. Thus, TiO₂ is regarded as basic oxide which acts as modifier in this ternary system in terms of its structure within this system.