Composition and diffusion properties of γ-FeOOH deposited in sulphate solutions

γ-FeOOH layers have been deposited by electrochemical oxidation of Fe2+ in 0.25 M Na2SO4. Results show that the bulk properties of the oxide, as represented by the diffusion coefficient of a process occurring across the layers during the oxide growth, undergo strong variations with increasing the oxide thickness. AES depth profiles of the samples show that sulphate is incorporated in the layers with a thickness dependent concentration. The diffusion coefficient of the sulphate-rich part of the layer is comparatively lower than the one of the sulphate depleted oxide. © 1988.