Efficiency of the Galvanostatic Formation of Anodic Antimony Oxide in Oxalic Acid Solutions

The formation of thick anodic oxide films on antimony in diluted solutions of oxalic acid (CO(OH) 2 ) was studied under galvanostatic and isothermal conditions. The film formation was always accompanied by a dissolution process which strongly depended on the growth conditions. The formation efficiency, as determined by the dissolved metal amount, was affected by the CO(OH) 2 concentration, the current density and the anodization time. The dissolved antimony amount increased with higher CO(OH) 2 concentrations and anodization time, and with lower current densities. The analysis of the total current density suggests the occurrence of a formed film and a dissolving component. According to the calculations, the anodic oxides composition is close to Sb 2 O 3 . The growth of anodic Sb 2 O 3 took place at high electric fields within the oxide film. The thicknesses of the formed films were calculated by taking into account their dissolution. The film formation efficiency was determined at various current densities.