In-Situ Monitoring of Metal Dissolution during Anodization of Tantalum

The dissolution of Ta in acidic media during both potentiodynamic and potentiostatic anodic oxide formation was quantified in-situ by ICP-MS. Potentiodynamic polarization yields a constant dissolution rate of 4 pg s −1 cm −2 (5 fm s −1 ) while a continuous dissolution rate decay was observed during potentiostatic anodization. The rate of Ta species release increased with applied potential in good agreement to the measured current density transients. A higher percentage of the charge carriers was identified as responsible for generation of soluble Ta species in potentiostatic regime as compared to potentiodynamic oxide growth. The current efficiency of anodization was determined from the combined investigation to exceed 99.9%.