Stability of iridium oxide films in high temperature, 200-250 degrees , solutions

The stability of reactively sputtered iridium oxide films on alumina substrates on exposure to pH 4, 7, and 10 solutions at 200 degrees C and 250 degrees C is examined. The exposures were made in a Teflon-lined bomb. The results of over 50 tests, cycling pH between 2 and 10 before and after exposure, are discussed. Changes of E degrees , the formed potential, and the slope were most severe under acidic conditions at 250 degrees C. The most severe conditions also caused film breakdown and loss of adhesion to the substrate. The incorporation of ion-assisted deposition in the fabrication of the films led to improved adherence under the most severe conditions of exposure. The results indicated similar behavior for films deposited at 500 K (crystalline) and those deposited at room temperature (amorphous).<>