NiMo_2B_2のNi周囲の局所的電子状態の検討 Local Electronic States around Nickel Atom in NiMo_2B_2
Local electronic states around Ni atom in NiMo<SUB>2</SUB>B<SUB>2</SUB> having an orthorohmbic crystal structure were investigated using the DV-X a molecular orbital calculation. It was found that the ionicity of Mo was positive and that of B was negative by the charge transfer from Mo atom to B atom. Ni acted as an accepter of electrons from Mo and a donor of electrons to B, and consequently its ionicity was neutral. The bond orders of Ni-B, Mo-B and Ni-Mo were very high. That is, covalent bonds of these pairs were very strong. The partial densities of states for 3d of Ni, 4d of Mo, and 2s and 2p of B were mutually widely overlapped. This is probably the reason for the high strength of the covalent bonds among Ni, Mo and B. The Fermi level existed near the peaks of the partial densities of states of 4d of Mo and 2p of B, indicating that the phase transformation of NiMo<SUB>2</SUB>B<SUB>2</SUB> from the orthorohmbic to tetragonal structure may be caused by substitution of Cr for a part of Ni.
粉体および粉末冶金 43(10), 1242-1246, 1996-10-15
Japan Society of Powder and Powder Metallurgy