Electronic and structural studies of intercalated graphite and buckminsterfullerene
The surface electronic and structural properties of binary MC[sub x] and ternary MM[prime]C[sub x] donor graphite intercalation compounds (GICs) were investigated using scanning tunneling microscopy (STM) and other surface sensitive techniques. The STM images revealed previously unobserved superstructures in the local density of states contours. This superstructure has been interpreted as a modulation of the surface density of states due to the underlying commensurate intercalate lattice. Other GICs exhibit longer wavelength incommensurate superstructures. The direct-space wavelength of these incommensurate superstructures was found to scale inversely with the amount of charge transferred from the intercalate to the graphite layers. Such a correlation is consistent with the wavelength dependence on Fermi surface expansion of a charge density wave (CDW) state. STM investigations of adsorbed films of collodial BiI[sub 3], prepared by a solution-phase method, revealed the presence of mono-disperse 10-50 [angstrom] single-layer particles with atomic resolution. This investigation demonstrated both the validity of the preparative method for the BiI[sub 3] particles and the capability of the STM to atomically resolve small semiconducting particles. The structural and superconducting properties of alkali metal intercalated Buckminsterfullerene (C[sub 60]) were also investigated. A new preparatory method was developed using heavy metal alloys instead of pure alkali metal. It was discovered that high superconducting fraction intercalation compounds could be prepared under milder conditions than by using the pure alkali metal. Intercalation of Hg, Tl and Bi alloys of Cs was found to form a superconducting phase. Finally, other investigators have empirically derived a linear dependence of T[sub c] on lattice constant for intercalated C[sub 60]. This dependence has been used to model the electron pairing mechanism for the superconducting state.
- Research Organization:
- Harvard Univ., Cambridge, MA (United States)
- OSTI ID:
- 7004084
- Resource Relation:
- Other Information: Thesis (Ph.D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
36 MATERIALS SCIENCE
FULLERENES
ELECTRONIC STRUCTURE
MICROSCOPY
SUPERCONDUCTIVITY
SURFACE PROPERTIES
GRAPHITE
TUNNEL EFFECT
CARBON
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ELEMENTAL MINERALS
ELEMENTS
MINERALS
NONMETALS
PHYSICAL PROPERTIES
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