抄録
Graphite films prepared from aromatic polyimides and a3000°C-treated grafoil were mixed with iron and heat-treated up to 2700°C and/or above. Effects of iron on the transverse magnetoresistance Δρ/ρ0, Hall coefficient RH and residual resistivity ratio RRR of these iron-doped graphite materials have been investigated. RH data imply that only a small amount of iron can substitute into the graphite lattice irrespective of the crystal perfection, and act as acceptors and impure. The heat treatment of graphite materials mixed with iron induces a decrease of Δρ/ρ0 and RRR for the original specimens with RRR>4, but an increase for those with RRR<4. These results indicate that the improvement of crystallinity of graphite materials through a catalytic action of iron becomes predominant for the specimens with RRR<4.
