Solid state 19F NMR study of acceptor-doped fullerenes (MF 6) 2C 60 (M=As, Sb)

• Published in: Physica. B, Condensed matter Vol. 327; no. 1; pp. 102 - 107
• Main Authors: Panich, A.M., Vieth, H.-M., Ummat, P.K., Datars, W.R.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 2003
• Subjects: Doped fullerenes; Fullerenes; Nuclear magnetic resonance (NMR); Doped fullerenes; 71.20.Tx; Fullerenes; 61.48.+c; 76.60.−k; Nuclear magnetic resonance (NMR); 81.05.Tp
• ISSN: 0921-4526; 1873-2135
• DOI: 10.1016/S0921-4526(02)01708-8

We report on temperature-dependent 19F NMR measurements of solid C 60 intercalated with AsF 5 and SbF 5 acceptor species. Structure, molecular dynamics and possible phase transitions in the compounds are studied. The temperature dependence of the second moment, S 2, of (AsF 6) 2C 60 is typical for activation of molecular mobility on heating. The reorientation of the (AsF 6) − complex is random and lasts at least down to 67 K. The temperature dependence of S 2 for (SbF 6) 2C 60 showing significant change in the range of 200–270 K is discussed. Further narrowing of the 19F spectra of (SbF 6) 2C 60 on heating occurs around 320 K. 19F spectra at 7.04 T resolve two resonances corresponding to different fluorine species. Suggesting that these species randomly occupy two different interstitial sites, we give reasons for the absence of superconductivity down to 5 K in the compounds under study.