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⋅6H₂O, 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⋅6H₂O→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-l-butanol (n-BuOH) to the chlorides remarkably decreased the decomposition temperature and the matallic Jr was taken out below 450°C and IrO₂ 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 Ru0₂ was taken out directly above 500°C. Under the atmosphere of Ar, Ru was easily taken out by heating RuCla dissolved in n-BuOH.