Studies on Thermal Decomposition of Iridium and Ruthenium Chlorides

Abstract

In order to obtain basic data for preparing of noble metal-coated electrodes, the decomposition processes of iridium chlorides such as H2IrCl6.6 H2O, IrCl3 and IrCl4.H2O and ruthenium trichloride, RuCl3.nH2O, and also the alcoholic solutions of these chlorides were studies by means of TG, DTA and X-ray diffraction. Although H2IrCl6 decomposed stepwisely according to the order of H2IrCl6.6 H2O→IrCl4→IrCl3→Ir→IrO2, IrCl4 separately prepared decomposed in a different way from IrCl4 detected under the heating process of H2IrCl6. A small difference in the crystalline structure would cause a difference in the process of decomposition. Addition of an alcohol like-1-butanol (n-BuOH) to the chlorides remarkably decreased the decomposition temperature and the matallic Ir was taken out below 450°C and IrOz was obtained above 450°C. From RuCl3, under air, matallic Ru was obtained neither in the presence nor in the absence of n-BuOH, but RuOa was taken out directly above 500°C. Under the atmosphere of Ar, Ru was easily taken out by heating RuCl3 dissolved in n-BuOH. © 1988, The Chemical Society of Japan. All rights reserved.