Preparation and characterisation of chromium and sodium tantalate layers by anodic spark deposition

A plasma-electrochemical synthesis was used to prepare chromium and sodium tantalate layers. These layers were deposited on a tantalum anode surface as ceramic compounds from aqueous electrolytes. The typical pore structure morphology of the tantalate layer was characterised by SEM as well as fractures which provide evidence of an intimate contact between layers and substrate. An XRD-study showed that the layers are composed of a mixture of Ta2O5 and either NaTaO3 or CrTaO4 depending on the electrolyte composition. Quantitative characterisation by EPM indicated higher chromium and tantalum concentrations on the electrolyte/layer interface than at the layer/tantalum interface. The chemical state of tantalum was investigated by means of XPS.