Magnetic properties of activated carbon fibers

Abstract

Magnetic susceptibilities and ESR spectra were measured for pitch-based activated carbon fibers (ACF) having huge specific surface areas (≈3000m²/g). These fibers consist of ca. 10Å micro-pores with which dangling bond spins are associated. Under an atmospheric condition, a broad weakly temperature dependent ESR signal (ΔH≈800G) was observed, while evacuation of the sample generates a narrow ESR signal (ΔH≈40G) with Curie law behavior superimposed upon the broad signal. From the experimental results for gas adsorption and heat-treatment effects, the narrow signal and the broad signal are respectively assigned to isolated dangling bond spins and conduction electron spins interacting with dangling bond spins directly attached to graphitic skeletons.