LOW TEMPERATURE GALVANOMAGNETIC PROPERTIES OF GRAPHITES
The electrical resistances and Hall coefficients of poly crystalline graphite, neutron irradiated graphite, chemically doped graphite, and neutron irradiated chemically doped graphite were measured over a range of magnetic fields at liquid nitrogen and liquid helium temperatures. The empirical equivalence of acceptor concentrations in irradiated graphite and in chemically doped graphite obtained by matching Hall coefficients was found to be a function of the temperature of measurement. This observation may be explained in terms of temperaturedependent trapping efficiencies of the electron traps intro duced chemically or by neutron irradiation. This explanation affords some understanding of the electrical properties of the complicated neutron irradiated chemically doped graphite. The temperature variation of the resistances and Hall coefficients of the graphites studied may be reasonably well understood on the basis of the phenomenological theory of transport properties. Anomalous variations with magnetic field of resistances and Hall coefftcients were observed at low temperature in some of the graphites studied; no satisfactory explanation has been found for these effects, although a recently introduced theory provides a plausible explanation for the observed magnetoresistance of polycrystalline graphite at liquid helium temperature. (auth)
- Research Organization:
- Argonne National Lab., Ill.
- DOE Contract Number:
- W-31-109-ENG-38
- NSA Number:
- NSA-17-011103
- OSTI ID:
- 4729637
- Report Number(s):
- TID-16243; UAC-6477
- Resource Relation:
- Other Information: Orig. Receipt Date: 31-DEC-63
- Country of Publication:
- United States
- Language:
- English
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