Defect structure and properties of pyrolytic carbons

摘要: Defects have been studied systematically in graphites prepared by the pyrolysis of methane at temperatures range 1600 to 2200 $^\circ$C. Physical methods used included measurements bulk density and studies X-ray diffraction photographs. Electronic properties examined were electrical resistivity its degree anisotropy, magneto-resistance, Hall effect, thermoelectric power. The uptake bromine saturation room temperature was characterize structural disorder chemical means. One main conclusion is that a striking change occurs pyrolytic carbons as their deposition passes through critical region, around 1900 Specimens below this low densities, show only comparatively small preferred orientation, contain appreciable concentrations residual hydrogen. deposited above densities other which tend towards those perfect graphite. crystal orientation improves progressively specimens up $^\circ$C can be brought still closer ideal graphite subsequent recrystallisation 2700 A second finding a-axis power, whose values lead same general conclusions about defects used, shows remarkable anomalies lowered reduced T/$\theta$ 0.03. preliminary examination has made changes resulting from compound formation neutron bombardment. Tentative attribution these interaction charge carriers with lattice vibrations.