Thermal Stability of Sputtered Iridium Oxide Films

“Dry” and partially hydrated films of IrO 2 were prepared by reactive sputtering. Their thermal stability was investigated by means of XPS, x‐ray diffraction, and resistivity measurements. Dry films decomposed at about 400°C in air and at 200°C in vacuum (10 −2 Pa), whereas partially hydrated films decomposed at 350° and 150°C, respectively. After electrochemical treatments of the films mounted as electrochromic electrodes in an electrolytic cell, the decomposition occurred at different temperatures. In particular, the bleached state was found to have the relatively low decomposition temperature of about 100°C in air.