Stresses of a titanium thin-film electrode generated during anodic oxidation by a beam-bending method

The changes in stress of anodic oxide film during anodic oxidation of the t itanium electrode, which was prepared on a glass plate by a magnetron sputt ering method, were measured quantitatively by a beam-bending method. The an odic oxidation of titanium was performed in pH 8.4 borate solution by a pot ential step from an open-circuit potential (0.33 V-RHE) to a certain potent ial. The compressive stress of ca. 0.5 GPa was generated in the anodic oxid e film during anodic oxidation for 1 h in the potential range 1.7-10.7 V-RH E. Moreover. the compressive stress of the anodic oxide film due to electro striction was measured by a cathodic potential sweep from the film formatio n potential to the flatband potential (0 V-RHE) Of the anodic oxide film, a nd its value was in good agreement with the calculated value. The compressi ve stress due to electrostriction was only 2-4% of the total compressive st ress of the anodic oxide film. The Pilling-Bedworth ratio of the Ti/TiO2 fi lm system supported the compressive stress of the anodic oxide film due to volume expansion of film formation. The transference number of oxygen ions in the film and the annihilation of ion vacancies were taken into considera tion as factors influencing the compressive stress of the anodic oxide film . (C) 2000 The Electrochemical Society. S0013-4651(00)06-063-8. All rights reserved.