Lattice dynamics of alpha uranium

Technical Report · Sun Jan 01 04:00:00 EST 1978

OSTI ID:6652745

Crummett, W P

Inelastic neutron scattering measurements of the phonon dispersion curves along the three-principal high-symmetry directions have been performed to investigate the lattice dynamics of ..cap alpha..-U. The dispersion curves along the (0 zeta 0) and (00 zeta) directions are not too unusual. However, dips and depressions are observed in the (zeta 00) branches similar to those observed in high-T/sub c/ superconductors. Standard group theoretical techniques have been employed to discern the symmetry properties of the phonon branches and to block diagonalize the dynamical matrix of the various phenomenological models that have been applied to ..cap alpha..-U. These phenomenological models include: a four neighbor Born-von Karman general tensor model, a twelve neighbor axially symmetric model, and a shell model. None of these models was able to satisfactorily fit the (zeta 00) data. However, a modified form of the shell model which included axially symmetric interactions to six neighbors was found to reproduce most of the dispersion curves well, including the (zeta 00) branches. A simple pseudopotential model was less successful. To obtain all real frequencies from this model it was necessary to include a Born-von Karman short range contribution. These measurements and calculations have implied that the bonding properties of ..cap alpha..-U are particularly dependent upon the details of the electronic system.

• Research Organization: West Virginia Univ., Morgantown (USA)
• DOE Contract Number: W-7405-ENG-26; EY-76-C-05-0033
• OSTI ID: 6652745
• Report Number(s): TID-28524
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102* -- Metals & Alloys-- Structure & Phase Studies
ACTINIDES
DISPERSION RELATIONS
ELEMENTS
LATTICE PARAMETERS
MATHEMATICAL MODELS
METALS
PHONONS
QUASI PARTICLES
SYMMETRY
URANIUM
URANIUM-ALPHA