Structural Investigation of Phosphorus in CaO-SiO₂-P₂O₅ Ternary Glass

Abstract

The system of CaO-SiO₂-P₂O₅ ternary glass is not only among the major constituents of steelmaking slags in iron and steel industry, but also play a significant role in other industrial process, such as chemical engineering and glass industry. In the present study, the structure of CaO-SiO₂-P₂O₅ ternary glass with varying P₂O₅ content from 0 to 15 wt pct at a fixed CaO/SiO₂ = 1.4 was investigated using molecular dynamics (MD) simulation combined with X-ray photoelectron spectroscopy and Raman spectra techniques. The results indicated that P⁵⁺ ions have a higher affinity to Ca²⁺ ions which are then stripped away from the silicate network with the addition of P₂O₅, resulting in the formation of Ca-O-P and Si-O-Si linkages. In addition, almost all P⁵⁺ ions displayed as ${\text{Q}}_{\text{P}}^{0}$ (${\text{Q}}_{\text{P}}^{n}$, n is the number of bridging oxygen in one [PO₄]-tetrahedra units) and a small fraction of P⁵⁺ ions behave as ${\text{Q}}_{\text{P}}^{1}$ (P-O-P) and P-O-Si. The enhanced degree of polymerization can be detected from the increase of ${\text{X}}_{\text{Si}}^{3}$ and $X_{\text{P}}^{1} /X_{\text{P}}^{0}$ (mole fraction of ${\text{Q}}_{\text{Si}}^{i}$ or ${\text{Q}}_{\text{P}}^{i}$). Furthermore, the ratio of Raman scattering coefficients for $Q_{\text{Si}}^{i} /Q_{\text{Si}}^{1}$ and $Q_{\text{P}}^{i} /Q_{\text{P}}^{1}$ were determined by combining MD simulated result with Raman spectra, which were considered to be suitable to the present study.