The hydrolysis reaction of some cubic and tetragonal lanthanide dicarbide solid solutions

Abstract

Two series of solid solution dicarbides made from a light and a heavy dicarbide, Er 1- x Ce x C 2 and Lu 1- x La x C 2, have been made and the change in X-ray lattice parameters across the series of tetragonal and cubic phases determined. Deviations from Vegard's law behaviour are discussed. Both series have been hydrolysed in water vapour at 11.0 × 10 2Nm −2 pressure and 14.5 °C and the rate constants for the linear reaction determined. The reaction rates for the Lu 1- x La x C 2 samples with water have been measured together with four cubic phases, Lu 0.5La 0.5C 2, Lu 0.5Ce 0.5C 2, Lu 0.5Pr 0.5C 2 and Lu 0.5Nd 0.5C 2. The changes in linear reaction rate constants for these samples, together with those of CeC 2 and LuC 2, are discussed in terms of CC bond lengths and f character of the metal band electrons which contribute to the MC 2 covalent bond. The reactivity sequence CeC 2 > Ce 0.5 Lu 0.5 C 2 ⪢ LuC 2 is explained.