Electronic properties of well oriented graphite

Abstract

A range of dense well oriented graphites of high chemical purity has been prepared by stress recrystallization of pyrolytic material. Systematic trends in the galvanomagnetic and thermoelectric properties have been investigated in relation to c-axis distribution function, crystallite size, and basal plane dislocation concentration, using temperatures from 300 to T2 °K and magnetic fields up to 6700 G. Basal plane properties of ideal graphite are evaluated in terms of the trends observed. Electronic properties have been measured parallel to the c axis for corresponding graphites with a range of defect concentrations. From the trends established, estimates are made of various properties of ideal defect-free graphite in the c -axis direction, and of anisotropy ratios. Effects of neutron irradiation on some of the electronic properties are also described. Results are discussed in terms of multi-carrier models.