Phonon dispersion of transverse basal-plane modes in alkali-graphite compounds

Conference · Mon Nov 01 04:00:00 EST 1982

OSTI ID:5865954

Kamitakahara, W A; Zabel, H; Nicklow, R M

Dispersion curves for low-frequency transverse modes propagating in the basal plane have been measured in the compounds KC/sub 8/, KC/sub 24/ and RbC/sub 24/ by means of neutron inelastic scattering. The acoustic branches show at low q a behavior ..omega../sup 2/ = Aq/sup 2/ + Bq/sup 4/ characteristic of layered materials. The optical branches are derived qualitatively from graphite-like optical branches hybridized with new alkali-like branches. In stage 2 compounds, the shear constant C/sub 44/, which can be obtained by extrapolating the acoustic branch towards q = 0, is appreciably smaller than in stage-1 compounds or in pure graphite. At low temperatures, it was noted in KC/sub 24/ that a frequency gap in the acoustic branch opens up near q = 0.6 A/sup -1/, corresponding to the Brillouin zone boundary of the low temperature alkali superstructure.

• Research Organization: Ames Lab., IA (USA); Illinois Univ., Urbana (USA). Dept. of Physics; Oak Ridge National Lab., TN (USA)
• DOE Contract Number: W-7405-ENG-82
• OSTI ID: 5865954
• Report Number(s): IS-M-423; CONF-821107-56; ON: DE83015211
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360602* -- Other Materials-- Structure & Phase Studies
ALKALI METAL COMPLEXES
BARYONS
CARBON
CLATHRATES
COMPLEXES
DISPERSION RELATIONS
ELEMENTAL MINERALS
ELEMENTARY PARTICLES
ELEMENTS
FERMIONS
GRAPHITE
HADRONS
INELASTIC SCATTERING
MINERALS
NEUTRONS
NONMETALS
NUCLEONS
PHONONS
POTASSIUM COMPLEXES
QUASI PARTICLES
RUBIDIUM COMPLEXES
SCATTERING