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 a s ceramic compounds from aqueous electrolytes. The typical pore structure m orphology of the tantalate layer was characterised by SEM as well as fractu res which provide evidence of an intimate contact between layers and substr ate. An XRD-study showed that the layers are composed of a mixture of Ta2O5 and either NaTaO3 or CrTaO4 depending on the electrolyte composition. Quan titative characterisation by EPM indicated higher chromium and tantalum con centrations on the electrolyte/layer interface than at the layer/tantalum i nterface. The chemical state of tantalum was investigated by means of XPS.