Bonding in the molybdenum silicides

Journal Article · Sat Oct 15 04:00:00 EDT 1994 · Physical Review, B: Condensed Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.50.10742· OSTI ID:6975800

McMahan, A K; Klepeis, J E ^[1]; van Schilfgaarde, M ^[2]; Methfessel, M ^[3]

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1. Lawrence Livermore National Laboratory, University of California, Livermore, California 94550 (United States)
2. SRI International, 333 Ravenswood Avenue, Menlo Park, California 94025 (United States)
3. Institut fuer Halbleiterphysik, P.O. Box 409, D-15204 Frankfurt an der Oder (Germany)

Full-potential linear muffin-tin orbital calculations are reported for the bulk properties, density of states, and electron density in [ital A]2 Mo, [ital A]15 Mo[sub 3]Si, [ital D]8[sub [ital m]] Mo[sub 5]Si[sub 3], [ital C]11[sub [ital b]] MoSi[sub 2], and [ital A]4 Si. Both the magnitude and the directional anisotropy of the valence charge density associated with bonds in the three silicides suggest a hierarchy in bond strength, ordered from strongest to weakest: Mo-Mo, Mo-Si, and Si-Si. A combined Mulliken and tight-binding analysis shows this behavior to coincide with variations in occupation of the respective types of bonding states, which is ultimately traced to Mo(4[ital d]) site energies that are nearly degenerate with the Fermi level, in contrast to Si(3[ital p]) site energies lying about 5 eV higher. These characteristics point to the dominance of Mo-Si bonding in [ital C]11[sub [ital b]] MoSi[sub 2], consistent with the near [ital pd] hybridization gap in this material, which appears to explain the unique position of the disilicide in systematics of the molybdenum silicide bulk properties. Finally, having identified the critical elements of the electronic structure in the molybdenum silicides, this work provides a physically motivated basis upon which to improve models used in the study of large-scale Mo-Si interface problems.

• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 6975800
• Journal Information: Physical Review, B: Condensed Matter; (United States), Journal Name: Physical Review, B: Condensed Matter; (United States) Vol. 50:15; ISSN PRBMDO; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360606* -- Other Materials-- Physical Properties-- (1992-)
ANISOTROPY
CHEMICAL BONDS
ELECTRON DENSITY
ELECTRONIC STRUCTURE
ENERGY-LEVEL DENSITY
HYBRIDIZATION
MOLYBDENUM COMPOUNDS
MOLYBDENUM SILICIDES
MUFFIN-TIN POTENTIAL
POTENTIALS
REFRACTORY METAL COMPOUNDS
SILICIDES
SILICON COMPOUNDS
TRANSITION ELEMENT COMPOUNDS