Magnetic and EPR studies of edge-localized spin paramagnetism in multi-shell nanographites derived from nanodiamonds

V. Yu Osipov, A. I. Shames, T. Enoki, K. Takai, M. Endo, T. Hayashi, Y. Kaburagi, A. Ya Vul'

Research output: Contribution to journalArticlepeer-review

18 Scopus citations


Prolonged (up to 2 h) heat treatment at 1600 °C of nanodiamond particles (5 nm) leads to their conversion to the mixture of quasi-spherical carbon onions and multi-shell polyhedral nanographites. Structural and magnetic properties of two (A and B) series of nanographite samples obtained at various annealing intervals were studied. XRD data show that both multi-shell nanographite samples have practically the same crystalline structures. HRTEM evidences that the most of particles obtained by short time (7 min) annealing have a spherical like shape whereas the long time (~ 2 h) annealing leads to the majority of particles having a polyhedral shape with a hollow inside. Electronic and magnetic properties of these nanocarbons were investigated by magnetic susceptibility and EPR. Annealing results in entire transformation of the EPR signal of nanodiamond to new EPR signals of various line shapes and widths. These signals are extremely sensitive to ambient oxygen. Concentrations for all EPR active spins vary from ~ 1 × 1019 spins/g (7 min) to ~ 2 × 1019 spins/g (2 h). Temperature dependences of EPR spectra' parameters were obtained for vacuum-processed samples within the range 4-600 K. Intensity vs. T plots may be well-fitted by the combination of Curie-Weiss and temperature-independent Pauli susceptibility contributions. The latter one increases on heat treatment. Significant extension of electron spin-lattice relaxation time on decreasing temperature was found.

Original languageEnglish
Pages (from-to)220-223
Number of pages4
JournalDiamond and Related Materials
Issue number2-3
StatePublished - 1 Feb 2009


  • Edge electronic states
  • Electron paramagnetic resonance
  • Graphite nanoparticles
  • Magnetic susceptibility

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • General Chemistry
  • Mechanical Engineering
  • Materials Chemistry
  • Electrical and Electronic Engineering


Dive into the research topics of 'Magnetic and EPR studies of edge-localized spin paramagnetism in multi-shell nanographites derived from nanodiamonds'. Together they form a unique fingerprint.

Cite this