3507.     ---------------.  [TUTIYA, H.].  X-Ray Observation of Molybdenum Carbides Formed at Low Temperatures.  Bull. Inst. Phys. Chem. Research (Tokyo), vol. 11, 1932, pp. 1150-1156; Sci. Papers Inst. Phys. Chem. Research (Tokyo), vol. 19, No. 384-392, 1932; Chem. Abs., vol. 27, 1933, p. 216.

        Mo atoms in Mo2C have the dense hexagonal lattice, 1 atom being in the position (1/3 2/3 ) and another in (2/3 1/3 ).  The C atom in the cell containing 1 mol. is perhaps in the position (0 0 0).  Lattice constants are:  a=2.994 . U., c=4.722 . U., c/a=1.577.  The atoms C and Mo in the unit cell of MoC have the following coordinates, respectively:  C (1/3 2/3 ), Mo (0 0 0); the lattice constants are: a=2.901 . U., c=2.786 . U., c/a=0.960, and, thus, the C atom in MoC has a radius of 0.785 . U.  No clear distinction between the lattice constants of MoC and of the metastable carbide phase was found; the reflections from the 2 carbides differ markedly in their relative intensities.