Sol‐Gel‐Syntheses and Structural as well as Electrical Characterizations of Anatase‐ and Rutile‐Type Solid Solutions in the System IrO(2)−TiO(2)

This paper describes solid solutions in the quasibinary oxide system iridium‐titanium IrO(2)−TiO(2) with rutile and anatase crystal structures. Based on X‐ray diffraction evaluations using Rietveld refinements, changes of lattice parameters were determined within the composition series of 0–100 mol % iridium. These changes prove the existence of a complete solid solution series in the rutile structure type. The solubility limit for iridium in the anatase lattice was found to be 6.0(8) mol % iridium for the underlying sol‐gel process. In addition, iridium is a promoter for the conversion from anatase to rutile type. Furthermore, the X‐ray diffraction results of a calcination temperature series for the composition with 5 mol % iridium are shown, which confirm the findings of the composition series and allow conclusions on the phase segregation behavior. The results are complemented by 2‐point conductivity measurements at different pressures in a piston press to investigate the question of the conductivity mechanism.