Accession Number : ADA017371

Title :   Cluster Calculations of the Effects of Local Bonding on the Electronic Properties of B6 Octahedra,

Corporate Author : NAVAL SURFACE WEAPONS CENTER WHITE OAK LAB SILVER SPRING MD

Personal Author(s) : Hemstreet,L. A.

Report Date : JUN 1975

Pagination or Media Count : 36

Abstract : B6 octahedra, which consist of six boron atoms in an octahedral arrangement, are important structural units in such materials as the metal hexaborides and the recently discovered boron-metal WANGNOL alloys. The X(alpha) Scattered Wave Method has been used to calculate the electronic properties of both an isolated octahedron and the effects of external environment. The latter has been investigated by surrounding a B6 octahedron by various configurations of atoms representing the local structure of the metal hexaboride and alloy materials. Results obtained from these calculations have been used to provide an explanation of the difference in properties between the metal hexaborides and the WANGOL alloys in terms of the difference in local bonding properties of the two materials. The bonding in the metal hexaborides is shown to be primarily ionic-covalent, while that of the WANGNOL alloys is found to be more ionic-metallic. This difference in bonding is shown to lead to quite different electronic and mechanical properties in the two classes of materials.

Descriptors :   *Boron, *Molecular orbitals, *Crystal lattices, Wave functions, Energy Levels, Hartree-fock approximation, Chemical bonds, Mechanical properties, Measurement, Alloys

Subject Categories : Crystallography
      Atomic and Molecular Physics and Spectroscopy

Distribution Statement : APPROVED FOR PUBLIC RELEASE