An interferometric gas analysis system for the measurement of changes in stoichiometry in metal oxides

Abstract

A novel system for the measurement of changes in stoichiometry of metal oxides in equilibrium with CO₂-CO mixtures is described. In this system the change in the refractivity of the gas mixture above the oxide is measured, using an interferometer. The limit of sensitivity of the apparatus is 5*10^-7 mol of atomic oxygen, corresponding to a change of 5*10^-6 in the oxygen-metal ratio of a 0.1 mol sample of composition MO. Results of experiments on wustite (FeO) are presented, which are in good agreement with previously reported data. The system can also be used to follow reaction kinetics under suitable conditions, permitting studies of diffusion and other rate-limiting processes.