Synthesis of a New Ternary Nitride, Fe4W2N, with a Unique eta-Carbide Structure

ISSN： 0022-4596

Source： Journal of Solid State Chemistry, Vol.134, Iss.2, 1997-12, pp. : 302-311

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Abstract

The structure of a new ternary nitride, Fe4W2N, prepared using a metal-organic precursor synthesis route, has been determined by Rietveld refinement of the monochromatic X-ray powder diffraction data. The compound crystallizes in a cubic, eta-carbide structure, space group Fd3m (227), with Z=16 and a lattice parameter of a=11.0810(9) A. The refinement converged with Rwp=0.1273, Rp=0.0709, RI=0.0478, and S=1.72. The compound is isostructural with Fe4W2C, the ideal structure consisting of eight octahedra of metal atoms, a random mixture of which one-third are iron and two-thirds are tungsten, centered on a diamond cubic lattice and eight regular tetrahedra of iron atoms centered on a second diamond cubic lattice that interpenetrates the first through a ½,½,½ unit cell translation. Sixteen additional iron atoms are tetrahedrally coordinated around the iron tetrahedra and sixteen nitrogen atoms surround the metal octahedra in tetrahedral coordination. Copyright 1997 Academic Press.