화학공학소재연구정보센터
Chemical Physics Letters, Vol.341, No.5-6, 467-475, 2001
Synthesis of LixC60(x=1-28) fullerides under high-pressure and high-temperature conditions and their electrical properties
LixC60 with compositions of x = 1-28 were treated under 5 GPa at 573 K for 1 h in order to explore a new Li-doped C-60 polymer. Three types of Li-doped phases, i.e., trigonal (3R) two-dimensional (2D-) polymer, tetragonal (T) 2D-polymer, and fee monomer were obtained as single phases for x = 1, 4, 16, respectively by the high-pressure (HP) treatment. The C-60 molecules in the 3R and T 2D-polymers are linked via [2 + 2] cycloaddition at a distance of 9.3 Angstrom. Li4C60 prepared without the HP treatment was a new T 2D-polymer linked by the [2 + 2] cycloaddition. The IR spectra of the Li4C60 and the Li16C60 before and after the HP treatment suggested the existence of some degrees of covalency between the Li and C atoms. The electrical conductivity measurements showed that the (LiC60)(HP) 3R 2D-polymer, the (Li4C60)Wp T 2D-polymer, and the (Li16C60)(Hp) fcc monomer phases were semiconductors with the conductivities of 1.8 x 10(-4), 1.2 x 10(-1), 6.4 x 10(-1) Omega (-1) cm(-1) at room temperature, respectively.