aDepartment of Material Science, Graduate School of Material Science, University of Hyogo, 3-2-1 Kouto, Kamigohri, Hyogo 678-1297, Japan
bDepartment of Material Science, Himeji Institute of Technology, 3-2-1 Kouto, Kamigohri, Hyogo 678-1297, Japan
cDepartment of Molecular Assemblies, Institute for Molecular Science, National Institutes of Natural Sciences, 38 Nishigo-Naka, Myodaiji, Okazaki 444-8585, Japan
by P. Sheng.
Available online 12 August 2008.
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Abstract
New C70 fullerides with compositions of MgxC70 at 1<x≤5 were prepared by solid state reaction. While most samples with 1<x<4 were multiphase, a single phase was obtained at x=5. Mg5C70 was found to be a Mg-saturated phase and its x-ray diffraction profile was successfully assigned to a simple orthorhombic structure with a=1.684, b=1.462, and 
. Mg5C70 was found to be non-metallic and exhibited an anomaly in magnetic susceptibility at approximately 80 K. No superconducting transition was found for MgxC70 (1<x≤5) down to a temperature of 2 K.
Keywords: A. Fullerenes; B. Chemical synthesis; E. Electron paramagnetic resonance
PACS classification codes: 61.48.+c; 71. 20. Tx
Fig. 1. Temperature-reaction time phase diagram for MgxC70 products. Symbols ○ and 
denote the formation of fullerides MgxC70 and amorphous-like products, respectively.
Fig. 2. XRD profiles for (a) C70 cage-collapsed MgxC70 and (b) pristine C70 at RT. The data was measured by using Mo Kα radiation (
). Raman spectra for C70 cage-collapsed MgxC70 and pristine C70 are shown in (c) and (d), respectively. Arrows 1 and 2 in panel (c) indicate the positions of Raman spectral peaks characteristic of nanocrystalline graphite and amorphous carbon, respectively.
Fig. 3. XRD profiles for MgxC70 at x=0, 2, 3, 4 and 5, measured by using Mo Kα radiation (
) at RT.
Fig. 4. XRD profile of Mg5C70 at 298 K. The data was measured using SR (
). All reflections are assigned to a simple orthorhombic structure.
Fig. 5. ESR spectra of Mg5C70 powder at 3.0, 140 and 300 K. The spectrum at 300 K could be reproduced using two respective Lorentzian functions.
Fig. 6. Temperature dependence of (a) the spin susceptibility χs estimated from the integrated ESR intensity, (b) the peak-to-peak line width ΔHpp, and (c) the g-value for the broad and narrow signals in Fig. 5, respectively.
