High-pressure neutron-scattering studies of graphite and stage-two graphite-SbCl/sub 5/

Journal Article · Fri Jul 15 04:00:00 EDT 1988 · Phys. Rev. B: Condens. Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.38.1544· OSTI ID:7201192

Alzyab, B; Perry, C H; Zahopoulos, C; Pringle, O A; Nicklow, R M

The longitudinal-acoustic (LA) phonons propagating along the c axis in highly oriented pyrolytic graphite (HOPG) were investigated as a function of pressure up to 20 kbar using inelastic-neutron-scattering techniques. The phonon frequencies varied as ..nu..(P,q) = A(P)sin(c(P)q/2), where A(P) and c(P) indicate the pressure dependences of the zone-center LO frequency of B/sub 1//sub g//sub >1/ symmetry and of the c-axis lattice spacing, respectively. From the measurements, the mode Grueneisen parameter for the LA branch was estimated to be 1.5 x 10/sup -2/ kbar/sup -1/ (independent of q); the elastic constant C/sub 33/ for HOPG was found to be 3.40 x 10/sup 11/ dyn/cm/sup 2/ at 1 bar with a pressure coefficient of (1/C/sub 33/)(dC/sub 33//dP) = 2.91 x 10/sup -2/ kbar/sup -1/. The measured c-axis spacings were 6.71 and 12.72 A for HOPG and stage-2 SbCl/sub 5/-intercalated graphite, respectively, at atmospheric pressure; the corresponding compressibilities (1/c)(dc/dP) were -2.24 x 10/sup -3/ kbar/sup -1/ (HOPG) and -2.28 x 10/sup -3/ kbar/sup -1/ (SbCl/sub 5/). Elastic-neutron-scattering studies up to 20 kbar were undertaken to search for stage transformations, but no evidence of any phase transition was observed.

• Research Organization: Physics Department, Northeastern University, Boston, Massachusetts 02115
• OSTI ID: 7201192
• Journal Information: Phys. Rev. B: Condens. Matter; (United States), Journal Name: Phys. Rev. B: Condens. Matter; (United States) Vol. 38:2; ISSN PRBMD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360603* -- Materials-- Properties
ANTIMONY CHLORIDES
ANTIMONY COMPOUNDS
CARBON
CHLORIDES
CHLORINE COMPOUNDS
CLATHRATES
COHERENT SCATTERING
COMPRESSIBILITY
CRYSTAL-PHASE TRANSFORMATIONS
DIFFRACTION
ELASTICITY
ELEMENTAL MINERALS
ELEMENTS
GRAPHITE
GRUENEISEN CONSTANT
HALIDES
HALOGEN COMPOUNDS
INELASTIC SCATTERING
LATTICE PARAMETERS
MECHANICAL PROPERTIES
MINERALS
NEUTRON DIFFRACTION
NONMETALS
ORIENTATION
PHASE TRANSFORMATIONS
PHONONS
PRESSURE DEPENDENCE
PYROLYTIC CARBON
QUASI PARTICLES
SCATTERING
TENSILE PROPERTIES
VERY HIGH PRESSURE