Revisiting a rare intermetallic ternary nitride, Ni2Mo3N: Crystal structure and property measurements

The intermetallic ternary nitride, Ni2Mo3N, has been synthesized by the amm onolysis of a complexed mixed-metal chloride precursor. This compound cryst allizes in the cubic space group P4(1)32 [213] with Z = 4 and a lattice par ameter of a = 6.6340(2) Angstrom, as determined from powder X-ray and neutr on diffraction experiments and the Rietveld refinement of the neutron data collected at room temperature. The refinement converged with R-wp = 0.032, R-p = 0.025, R-I = 0.059, and chi(2) = 1.48. Ni2Mo3N assumes a filled beta- manganese structure, ideally consisting of a lattice of corner-sharing Mo6N octahedra in a five-membered ring arrangement and an interpenetrating net- like lattice of nickel atoms which occupy the pentagonal holes formed by th e molybdenum nitride polyhedral rings. Electrical and magnetic characteriza tion of Ni2Mo3N indicate that it is a metallic conductor which antiferromag netically orders at 14.7 K. Neutron diffraction conducted at 10 K suggests that the size of the magnetic unit cell matches that of the crystallographi c unit cell. A version of this nitride phase which is substoichiometric in nitrogen and therefore has a smaller lattice parameter also displays antife rromagnetic ordering, but with a much higher ordering temperature of 68.7 K . (C) 1999 Academic Press.