Characterization of the Structure of RuO2−IrO2/Ti Electrodes by EXAFS

The structure of oxide layers of the RuO 2 −IrO 2 /Ti electrode system and the thermal decomposition processes of RuCl 3 and IrCl 3 to form their respective oxides have been mainly analyzed by EXAFS (extended X-ray absorption fine structure) and XRD (X-ray diffraction). Upon heating of the respective chlorides in air, both chlorides convert into their respective oxides. The coordination numbers of the oxide ions around both the ruthenium and iridium ions increased with an increase in the calcination temperature and attained 6, which is the theoretical value of the standard samples of rutile RuO 2 and IrO 2 . The changes in the coordination number with respect to the calcination temperature were accompanied by changes in the lattice constants of these oxides. This suggests that the deviation of these parameters from the standard sample is caused by the lattice defects of the oxide ions. A dependence of the radial distribution functions of EXAFS on the composition of the RuO 2 −IrO 2 /Ti electrode system showed that RuO 2 forms a solid solution with IrO 2 for the binary oxide electrode system.