Research and Development on Advanced Graphite Materials: Volume VIII - Electron Spin Resonance in Polycrystalline Graphite

Item

Title
Research and Development on Advanced Graphite Materials: Volume VIII - Electron Spin Resonance in Polycrystalline Graphite
Date
1962
Index Abstract
Contrails and DTIC
Photo Quality
Not Needed
Report Number
WADD TR 61-72 Volume 8
Creator
Singer, L. S.
Wagoner, G.
Corporate Author
National Carbon Company
Laboratory
Directorate of Materials and Processes
Extent
25
Identifier
AD0288943
AD0288943
Access Rights
OTS
Distribution Classification
1
Contract
AF 33(616)-6915
DoD Project
7350
DoD Task
735002
DTIC Record Exists
Yes
Distribution Change Authority Correspondence
None
Abstract
The electron spin resonance of polycrystalline graphite is shown to be due to charge carriers, as for single crystals. For lampblack-base graphite, the variation in g-value with temperature agrees approximately with that for single crystal graphite if it is assumed that the spins effectively average out the anisotropic interactions by rapid intercrystallite diffusion. The magnitude and temperature dependence of the spin susceptibility are found to be in excellent agreement with McClure's theoretical predictions for the charge carriers in perfect graphite. Complications of measuring these materials are discussed, including effects of skin depth and microwave heating and the dependence upon crystallite size and sample purity. It is found that two types of impurities can affect the resonance; those which become ionized and shift the Fermi level, and large un-ionized atoms which do not shift the Fermi level but act as efficient scattering centers for shortening the spin-lattice relaxation time.
Report Availability
Full text available
Date Issued
1962-06
Subject
Carbon Black
Graphite
Paramagnetic Resonance
Conductivity
Crystal Structure
Heating
Impurities
Measurement
Microwaves
Publisher
Wright-Patterson Air Force Base, OH : Directorate of Materials and Processes, Aeronautical Systems Division, Air Force Systems Command
Distribution Conflict
No
Provenance
Lockheed Martin Missiles & Fire Control
Type
report
Format
1 online resource