Composition of Anodic Aluminum Oxides

The chemical composition of anodic aluminas, with special emphasis on the depth-dependent incorporation of electrolyte species (protons, anions, etc.), has been extensively studied. 

Nonstoichiometry of the oxides can be due to a number of reasons, such as hydration,159 incomplete oxidation,158 and the generation of defects at interfaces.157 An important factor affecting the chemical composition of the oxides is the incorporation of electrolyte species into the growing alumina. There have even been suggestions to use this for impurity doping of oxides and modifying their properties.161 Various kinds of anion distributions and mechanisms of anion incorporation and their influence on oxide properties have been reported. The problems attracting attention are  

Data on Anion incorporation into Anodic Alumina 

Anodizing bath Method of study Chemical state of anion and impurities Mean anion content Type of anion distribution0 k = LJL Ref. 

The anion distribution in anodic oxides is usually determined by ion bombardment or chemical sectioning of alumina samples with subsequent analysis by AES or XPS methods, or by the use of the depth-resolving techniques, such as RBS.150 Different types of concentration profiles are shown in Fig. 27. 

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