Thermodynamic Study of Fused SnO-SiO₂ System

Abstract

Thermodynamic properties of molten SnO-SiO₂ system were estimated by e.m.f. measurements employing solid electrolytes. The experiments were carried out at the temperature range of 1050°∼1150°C by means of the following galvanic cells.
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From these experimental results, it has been shown that,
(1) The standard free energy of formation of molten stannous oxide was shown by the following equation as a function of temperature.
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(2) The activities of stannous oxide in molten SnO-SiO₂ had a slight deviation from Raoult’s Law.
(3) Molal heats and entropy of mixing in the molten SnO-SiO₂ system were considerable positive larger values than those of ideal solution.
(4) The model of Toop and Samis were applied to the molten SnO-SiO₂ at 1100°C and the equilibrium constant K in the following reaction was found to be larger than 0.3.
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(5) This experimental result gives some support to the phase diagram of SnO-SiO₂ shown by Kohlmeyer et al.