Title

Research And Development On Advanced Graphite Materials. Volume XX - The Electric And Magnetic Properties Of Pyrolytic Graphite

Date

1963

Index Abstract

Contrails and DTIC truncated

Photo Quality

Not Needed

Report Number

WADD TR 61-72 Volume 20

Creator

Wagoner, G.

Eckstein, B. H.

Corporate Author

Research Laboratory of National Carbon Company Division of Union Carbide Corporation

Laboratory

AF Materials Laboratory

Extent

28

Identifier

AD0426185

AD0426185

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

Report Availability

Full text available

Date Issued

1963-11

Abstract

This paper concerns the electric and magnetic properties of a series of highly turbostratic pyrolytic graphic deposits. The diamagnetic susceptibility, Hall coefficient, and electron spin resonance g value are observed to have much larger magnitudes than corresponding measurements made on single crystals of graphite. The results are interpreted as being due to the turbostratic character of the deposit which brings about a decreased interaction between the randomly rotated graphitic planes. The overlap of the electron and hole bands is thereby reduced and as a first approximation one can interpret the results using the simple two dimensional model of Wallace. McClure's diamagnetism formula, which is based on the Wallace model, yields a maximum trace value of -39 emu/g. The largest observed value is -33.5 emu/g, a diamagnetism almost 50 per cent greater than the normal single crystal value of -22.8 emu/g.

To obtain from theory the large variation of g shift and diamagnetism as a function of formation temperature, it is necessary that acceptors be present whose concentration decreases as the temperature of formation increases. Similar acceptors have been postulated by others to explain the properties of high temperature carbons.

Publisher

Wright-Patterson Air Force Base, OH : AF Materials Laboratory, Research and Technology Division, Air Force Systems Command

Distribution Conflict

No

Provenance

IIT

Type

report

Subject

Magnetic Properties

Physical Properties

High Temperature

Graphite

Pyrolytic Crystal Structure

Preparation

Hall Effect

Theory

Metallography

Electrical Properties

Electrons

Mathematical Analysis

Vacuum Apparatus

Spinning (Motion)

Integral Equations

Format

1 online resource