Microstructure and electrical properties of IrO2 prepared by thermal decomposition of IrCl3·x H2O

Some features of the thermal decomposition of IrCl3·3 H2O in an oxygen atmosphere are presented. The formation of IrO2 phases has been followed by X-ray diffractometry, and the onset of definite reflections has been documented for samples pyrolyzed at 350° C, although moderate weight losses are observed by thermogravimetry at this temperature. The effect of the thermal history of iridium oxide coatings on their structure has been studied by means of electrical resistance measurements. An explanation of the results has been attempted in terms of impurity segregation to the oxide grain boundaries.