Magnetic Properties of Activated Carbon Impregnated with Iron after Hydrogen Reduction

Abstract

Recently the reasearch of organic ferromagnetism has been attracting much a ttention. In these works, quite often asked question is whether “the ferromagnetic materials” prepared by the researcher contains some trace amount of iron or not. This is unanswerable question in some cases. It is desirable to know, then, if a very trace amount of iron existing as a contamination to the organic substance under investigation determines the final magnetic behavior of the organic ferromagnetic material derived from it. Iron was impregnated into activated carbon from an aqueous solution of Fe(NO₃)3⋅9 H₂0 to the concentration of 0.01, 10%. After evaporating water, this Fe/activated carbon powder was reduced in H₂ atmosphere (10₅ Pa) at 350 °C for 60 min. Magnetization and ESR spectra were measured with the samples thus prepared. IR and reflection spectra were also observed using KBr discs in which activated carbon (with Fe) was diluted with KBr crystal powders at the concentration of 1 mg/150 mg. The results have indicated that iron-ferromagnetism can be observed only when iron concentration exceeds 6, 8%. If iron concentration is below 1%, the type of magnetism observed with Fe/activated carbon is qualitatively identical to that of pure activated carbon. These observations may permit us to say that “too excess caution about iron contamination” is unnecessary or useless when handling with organic ferromagnetic materials.