| Popis: |
Hydrous RuO 2 has been prepared by alkaline fusion of Ru+KNO 3 + KOH and successive decomposition of the ruthenate and perruthenate. The product has been analyzed by thermogravimetric analysis, differential thermal analysis, X-ray diffraction and scanning electron microscopy. Aqueous suspensions of samples of the hydrous oxide calcined at various temperatures between 300 and 500°C have been titrated potentiometrically to determine the point of zero charge. The results have been compared with commercial RuO 2 · x H 2 O. The two oxides have been found to differ in composition, structure, morphology and acid-base properties. In particular, hydrous RuO 2 contains chemically bound water besides physically bound water, which is the only water present in the commercial sample. The dependence of the point of zero charge of the hydrous RuO 2 on calcination temperature follows the same pattern as RuO 2 obtained by thermal decomposition of RuCl 3 , while the behaviour of the commercial sample diverges below the temperature where the chemically bound water is lost by the hydrous RuO 2 . |
