Structure of Haloform Intercalated C60 and its Influence on Superconductive Properties.

We have determined the crystal structure of CHCl[SUB3] and CHBr[SUB3] intercalated C[SUB60] using synchrotron x-ray powder-diffraction, and found that the expansion of the lattice mainly takes place in one dimension (triclinic b-axis), leaving planes of C[SUB60] molecules on an approximately hexagonal, slightly expanded lattice. We have performed tight-binding band structure calculations for the surface layer. In spite of the slight expansion of the layers, for the range of dopings where a large T[SUBc] has been observed, the density of states at the Fermi energy is smaller for C[SUB60]-2CHCl[SUB3] and C[SUB60].2CHBr[SUB3] than for C[SUB60]. This suggests that lattice expansion alone cannot explain the increase of T[SUBc]. [ABSTRACT FROM AUTHOR]