Paramagnetic resonance of Shungite – a natural nano‐structured carbonaceous material

Shungites Sh‐III and Sh‐IV (∼50% and 20% of carbon) have been studied by X‐band EPR method in the range 4.2–293 K. The week signal of Dyson shape ( a / b = 2.25–2.40) observed from a bulk sample of Sh‐III has been observed to transform into an intensive Lorentzian line (Δ B = 1.99 mT, g = 2.0020) after sample grinding. The number of EPR responsible spins (2 × 10 19 g –1 ) and the depth of penetration δ (∼60 µm) have been estimated. The shape of the signals (Dysonian or Lorentzian) is independent of T . Δ B and the g values decrease below 80 K to 1.15 mT and 2.0012. The signal intensity is independent of T down to 150 K. Isolated complexes of C 60 (C 70 ) – n with K + (Na + ) have been found in Sh‐IV. Analysis of the EPR spectra has been made taking into consideration the properties of the conductive materials such as metals and graphite. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)