Self-Diffusion of Oxygen in CaO-SiO₂ Melt

Author： Shiraishi Yutaka Nagahama Hiroshi Ohta Hiromichi

ISSN： 0008-4433

Source： Canadian Metallurgical Quarterly, Vol.22, Iss.1, 1983-01, pp. : 37-43

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Abstract

Self-diffusion coefficient of oxygen has been measured by the capillary reservoir method in 56 mol % CaO–44 mol % SiO₂ melt and the temperature range between 1550and 1650°C under the atmosphere of high purity argon with 3% H₂ or of vacuum. As the tracer, stable isotope ¹⁸O was used in the form of SiO₂^* prepared from ¹⁸O enriched water and SiCl₄. The diffusion coefficient was derived from the concentration-penetration curve which was determined by the mass analysis of CO₂^* combined with the carbon arc reduction of the capillary sample sectioned after diffusion run.The results obtained showed the end effect of the capillary which means that the effective length postulated by the theoretical concentration profile differs from the real length of the capillary. With the consideration of this effect, the following expression was obtained by the least squares regression on the theoretical solution of the Fick's second law:D = 1.5 × 10⁷ exp[( −408 ± 36)/RT], in cm² S⁻¹ & kJmol⁻¹, (1550–1650°C).Comparison with previous data and discussion were made about the composition dependency of the self-diffusivity of oxygen.