Tracer diffusivity of Si31 in CaO-SiO2 melts at 1600°C

Molecular Dynamics Simulation of the Thermodynamic and Structural Properties for the CaO-SiO2 System

“…These results represent reasonably well the structural properties of CaO-SiO 2 melts, which were restricted to the diffusion of Si and O ions by the formation of silica network structure in the melts. The calculated self-diffusion coefficients of Ca, Si and O ions are in good agreement with measured values by Keller et al [28][29][30] For the calculation of the degree of polymerization in CaO-SiO 2 melts, the fractions of oxygen species such as bridging (O ) oxygen were calculated as a function of composition. The cut-off distance between Si and O ions for the calculation of oxygen species was determined by minimum position of first peak in silicon-oxygen pair distribution function, g Si-O (r).…”

“…Figure 8 shows the calculated self-diffusion coefficients of Ca, Si and O ions as a function of composition at 1 873 K with observed results. [28][29][30] The calculated self-diffusion coefficients of each ion show the relationship D Ca ϾD O ϾD Si and decrease with increasing SiO 2 content in CaO-SiO 2 melts. These results represent reasonably well the structural properties of CaO-SiO 2 melts, which were restricted to the diffusion of Si and O ions by the formation of silica network structure in the melts.…”

Multicomponent diffusion in molten slags

“…Several authors [3,6,24] reported iron to have diffusivities an order of magnitude greater than calcium. Keller and Schwerdtfeger [6] and Nowak and Schwerdtfeger [24] proposed the high diffusivity of iron was due to an interaction between the lone electron pair on bridging oxygen and the 3d orbital of Fe 2ϩ . This reduces the jump energy for Fe 2ϩ between non-bridging oxygen, and consequently enhances the rate of diffusion.…”

Solid-state amperometric sensor for the In-situ monitoring of slag composition and transport properties

“…In agreement with equations 3.33 and 3.34, the tracer diffusivity of Ca 2 + is smaller than FeX+ indicating that the influence of Ca 2 + on the total slag conductivity is not nearly as strong as that of Fex+ per unit of concentration. Schwerdtfeger et al [75,76 ] used both electrochemical and porous frit techniques to determine that the self diffusion coefficients of Fe 2 + and Ca 2 + at 1600 0 C for SiO 2 saturated slags were approximately 1-3x10 5 cm 2 /sec and 1-2x10 cm 2 /sec respectively. Schwerdtfeger also demonstrated that the diffusivities remained largely independent of composition up to approximately 15 wt%FeOx as might be expected because the overall slag structure should remain largely unchanged in the Henrian regime.…”

“…Schwerdtfeger also demonstrated that the diffusivities remained largely independent of composition up to approximately 15 wt%FeOx as might be expected because the overall slag structure should remain largely unchanged in the Henrian regime. Goto [77] found that the tracer diffusivity for Fex+ (-3x10-5 cm 2 /sec) was approximately 3 times greater than that for Ca 2 + ions for 33CaO-27SiO 2 Nowackl 75] proposed that the 3d orbital of the Fe2+ ion allows it to achieve a transition state with the anionic network which Ca 2 + is unable to form. However, a conclusive mechanism has not yet been established.…”