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

Technical Report · Fri Jan 01 04:00:00 EST 1982

OSTI ID:5828021

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: AC02-76ER01198
• OSTI ID: 5828021
• Report Number(s): DOE/ER/01198-1394; CONF-821185-2; ON: DE83003910
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360202 -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
360204* -- Ceramics
Cermets
& Refractories-- Physical Properties
ALKALI METAL COMPOUNDS
CARBIDES
CARBON
CARBON COMPOUNDS
CLATHRATES
COHERENT SCATTERING
CRYSTAL LATTICES
CRYSTAL STRUCTURE
DATA
DIFFRACTION
DISPERSION RELATIONS
ELASTICITY
ELEMENTAL MINERALS
ELEMENTS
EXPERIMENTAL DATA
GRAPHITE
INELASTIC SCATTERING
INFORMATION
LAYERS
LOW TEMPERATURE
MECHANICAL PROPERTIES
MINERALS
NEUTRON DIFFRACTION
NONMETALS
NUMERICAL DATA
PHONONS
POTASSIUM CARBIDES
POTASSIUM COMPOUNDS
QUASI PARTICLES
RUBIDIUM CARBIDES
RUBIDIUM COMPOUNDS
SCATTERING
SHEAR
TENSILE PROPERTIES