From nitrides to carbides: topotactic synthesis of the η-carbides Fe3Mo3C and Co3Mo3C

Abstract

The molybdenum bimetallic interstitial carbides Fe₃Mo₃C and Co₃Mo₃C have been synthesized by temperature-programmed reaction (TPR) between the molybdenum bimetallic interstitial nitrides Fe₃Mo₃N and Co₃Mo₃N and a flowing mixture of CH₄ and H₂ diluted in Ar. These compounds have been characterized by X-ray diffraction, laser Raman spectroscopy, elemental analysis, energy dispersive analysis of X rays, thermal analysis (in air) and scanning electron microscopy (field emission). Their structures have been refined from X-ray powder diffraction data. These carbides crystallize in the cubic system, space group Fdm [a = 11.11376(6) and 11.0697(3) Å for Fe and Co compounds, respectively].