Phonon dispersion curves of nonstoichiometric Nb/sub 3/Ge

Journal Article · Sat Jun 15 04:00:00 EDT 1985 · Phys. Rev. B: Condens. Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.31.7772· OSTI ID:5792543

Smith, H G; Wakabayashi, N; Chang, Y K; Pintschovius, L; Weber, W

The phonon dispersion curves of nonstoichiometric Nb/sub 3/Ge (T/sub c/ = 6 K) have been investigated by inelastic neutron scattering. Despite the small size of the sample (0.1 cm/sup 3/) most of the branches along the main symmetry directions, including the highest-energy modes, have been determined. No drastic anomalies were observed and temperature effects were found to be small. The results can be well described by a Born--von Karman model with axially symmetric forces up to the seventh-nearest neighbors. In a search for electron-phonon coupling effects our results for Nb/sub 3/(Ge/sub 0.8/Nb/sub 0.2/) are compared to previous results obtained on the low-T/sub c/ compound Nb/sub c/Sb (T/sub c/approx. =0.2 K). The major differences between the lattice dynamics of the two compounds were found to be (i) a reduction of the Nb-Ge interaction by 35% compared to the Nb-Sb interaction and (ii) the low frequency of modes in Nb/sub 3/(Ge/sub 0.8/Nb/sub 0.2/) which involve a ''buckling'' of the Nb chains.

• Research Organization: Solid State Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830
• OSTI ID: 5792543
• Journal Information: Phys. Rev. B: Condens. Matter; (United States), Journal Name: Phys. Rev. B: Condens. Matter; (United States) Vol. 31:12; ISSN PRBMD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104* -- Metals & Alloys-- Physical Properties
BETA-W LATTICES
BORN-VON KARMAN THEORY
COHERENT SCATTERING
CRYSTAL LATTICES
CRYSTAL STRUCTURE
DIFFRACTION
DISPERSION RELATIONS
ELECTRON-PHONON COUPLING
ENERGY-LEVEL DENSITY
GERMANIUM COMPOUNDS
INELASTIC SCATTERING
LOW TEMPERATURE
MEDIUM TEMPERATURE
NEUTRON DIFFRACTION
NIOBIUM COMPOUNDS
PHONONS
PHYSICAL PROPERTIES
QUASI PARTICLES
REFRACTORY METAL COMPOUNDS
SCATTERING
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
TRANSITION TEMPERATURE