CHEMICAL SYNTHESIS AND STRUCTURAL INVESTIGATION OF A NEW TERNARY NITRIDE, CRWN2

A new ternary nitride, CrWN2, has been synthesized by the ammonolysis of a chemically derived metallorganic precursor, The structure is trig onal in the space group R3 (146) with Z=3, as determined from powder X -ray diffraction and Rietveld refinement of the resulting diffraction pattern. The refinement converged with R(wp)=0.1313, R(p)=0.0962, R(I) =0.0219, and chi(2)=1.82. Using hexagonal notation, the unit cell of C rWN2 has lattice parameters of a=2.8561(7) Angstrom and c=15.606(7) An gstrom. The compound is isostructural with LiMoN2, the ideal structure consisting of alternating close-packed layers of chromium in octahedr al coordination with nitrogen and tungsten in trigonal prismatic cordi nation with nitrogen. (C) 1997 Academic Press.