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

Abstract

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 (CNSi-O) changes from 4.12 to 4.03, while the CNTi-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 Q n 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.

Structure Analysis of CaO–SiO2–Al2O3–TiO2 Slag by Molecular Dynamics Simulation and FT-IR Spectroscopy

“…2. In addition, the variation of CNTi-O is larger than that of CNSi-O, which exhibits the same trend in the CaO-SiO2-TiO2 system in our previous work, 26) indicating that [SiO4] has a higher stability than [TiO6]. The variation of CNSi-Si, CNSi-Al, CNSi-Ca and CNSi-Ti with different additions of TiO2 is graphically presented in Fig.…”

“…The second item on the right hand denotes the short-range repulsion interaction between two atoms which are determined by parameters of Bij and Rij. The parameters were adopted from Zheng's work 25) as well as our previous study 26) to insure the accuracy. The parameters Bij and Rij, corresponding to the short-range repulsion interaction between two atoms, were listed in Table 1.…”

“…It can be concluded that both the degree of polymerization of Si and Al decreased with the addition of TiO2, demonstrating that TiO2 act as a basic oxide, which is consistent with previous studies by many investigators. 2,4,7,17,18,26) Furthermore, it should be noted that the proportion of Q 3 and Q 4 for Al are higher compared to that of Si, which indicating that Al is inclined to form more complex units than Si. The same conclusion was proposed by Shimoda 24) and Lee,34) by MD and NMR, respectively.…”

“…24) Zheng et al have also revealed the effect of Al2O3/SiO2 ratios on the structure of calcium aluminosilicate slags by MD simulation. 25) In our previous work, 26) the structure in CaO-SiO2-TiO2 system has been investigated with different additions of TiO2 at a fixed CaO/SiO2 ratio. In the present work, the MD simulation and FT-IR were combined to investigate the information of the structure in CaO-SiO2-14 mass% Al2O3-TiO2 slag with varying additions of TiO2 as well as different CaO/TiO2 ratios.…”

Structural Characterization of FeO–SiO₂–V₂O₃ Slags Using Molecular Dynamics Simulations and FT-IR Spectroscopy

“…Analogous compositional selection and research approaches have been adopted in recent structural and viscosity studies of CaO-SiO 2 -TiO 2 system. 27,28) …”