Doping of IBr into Graphite and Carbon Materials with Different Graphitization Degree

Abstract

Planar specimens of graphite (Grafoil) and carbon materials (artificial graphite materials derived from petroleum cokes) with different heat-treatment temperatures (HTT) were brought into contact with IBr vapor at 20°C. The resistance of the carbon materials decreased by the contact with IBr vapor. The relative resistance, R/R0, defined as the resistance of IBr-doped material divided by that of the starting carbon material was determined and minimum values were as follows: 0.095 for Grafoil, 0.116 for carbon material with HTT of 2800°C, 0.117 (HTT-2400), 0.167 (HTT-2200), 0.269 (HTT-2000), 0.862 (HTT-1750) and 0.838 (HTT-1000). The composition of the saturated compound was estimated to be approximately C16IBr. By the desorption of IBr from the doped specimens, stable residue compounds were obtained. The nominal composition of the residue compounds estimated from weight change was in the range of about C120IBr to C280IBr, depending on the host material. Values of electric resistance of the residue compounds were about half as much as those of the host materials.