The Preparation and Some Properties of the Lanthanide Oxidecarbides, Ln₄O₃C

A series of lanthanide oxidecarbides (Ln = La, Nd, Gd, Ho, Er) of fcc symmetry has been prepared by reducing the sesquioxide with appropriate mixtures of graphite and the corresponding lanthanide metal. The neodymium analog, which was studied extensively, was found to have the approximate stoichiometry Nd₄O₃C. The X-ray powder diffraction pattern of this phase is indexable on cubic symmetry and has a lattice parameter, a0 = 5.1407 ± 0.0001 Å. The X-ray intensities are consistent with a NaCl-type lattice. Vapor-phase chromatographic analysis of the hydrolysis products suggests the presence of C⁴- ions in the structure. Data presented indicate that this is a carbon-stabilized monoxide phase which is common to the lanthanide series.