Refine your search:     
Report No.

Structure evolution and corresponding electrical properties in weakly bound Co-C60 mixture

Sakai, Seiji; Naramoto, Hiroshi; Xu, Y.; Priyanto, T. H.; Lavrentiev, V.; Narumi, Kazumasa

Mixture films between cobalt and C$$_{60}$$ (CoxC$$_{60}$$, x = 0.5-700) were prepared by co-evaporation technique under UHV conditions. The composition-dependent features of dilatation and downshift of Raman peak suggest that the mixtures are composed of cobalt particles and a C$$_{60}$$-based phase in which certain number of cobalt atoms are coordinated with C$$_{60}$$ molecules. It is deduced that the equilibrated number of cobalt atoms in the C$$_{60}$$-based phase is 4 atoms per C$$_{60}$$ molecule and in which an electron transfer occurs from a cobalt atom to a C$$_{60}$$ molecule. The evaluation of their temperature dependences reveals that: (1) The mixtures with x $$leq$$ 4 are thermally activated-type, and their conductive nature can be attributed to the C$$_{60}$$-based phase. Further (2) the mixtures between 4 $$<$$ x $$<$$ 60 are also thermally activated, however, the electron hopping process between the isolated cobalt particles is supposed to be operative (variable-range-hopping). And (3) in the mixtures with x $$geq$$ 60 which corresponds to a percolation threshold for cobalt particles, the system changes into metallic conduction.



- Accesses





[CLARIVATE ANALYTICS], [WEB OF SCIENCE], [HIGHLY CITED PAPER & CUP LOGO] and [HOT PAPER & FIRE LOGO] are trademarks of Clarivate Analytics, and/or its affiliated company or companies, and used herein by permission and/or license.