STRUCTURE OF TA3N5 AT 16-K BY TIME-OF-FLIGHT NEUTRON-DIFFRACTION

Polycrystalline tritantalum pentanitride (Ta3N5) has been prepared from the reaction of TaCl5 with ammonia, and its structure has been refined from time-of-flight neutron diffraction data. M(r) = 612.88, orthorhombic, Cmcm, a = 3.8862 (1), b = 10.2118 (2), c = 10.2624 (3) angstrom, V = 407.26 (3) angstrom 3, Z = 4, D(x) = 9.99 g cm-3, neutron time-of-flight, Rietveld refinement, wR(p), R(p), reduced chi-2 = 0.061, 0.043, 4.21 for data collected at 16 K. Ta3N5 crystallizes with the pseudobrookite (Fe2TiO5) structure. Irregular TaN6 octahedra share edges and corners.