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