Single-crystal growth of C70S8 - a new phase in the C-70-sulphur system

Large crystals (up to 2 x 1 x 0.5 mm) of a new C-70-sulphur compound were g rown by evaporation of a benzene solution. The composition of this compound was determined by chemical analysis to C70S8. Single-crystal and X-ray pow der diffraction experiments showed that the phase has orthorhombic structur e with cell parameters a = 30.18, b = 30.41, and c = 28.32 Angstrom and the space group Pbcn. The Raman spectrum from the new compound was very simila r to those of pure C-70 and sulphur with the exception of some changes in r elative intensity and small shifts of a few peaks at wavenumbers below 500 cm(-1). The results suggest that the C-70-S-8 interactions mainly consists of weak van der Waals bonds. Some irregularities in the peak shifts suggest that the distribution of S-8 rings around the C-70 molecules are less symm etrical that in the well-known C70S48 phase. (C) 2000 Elsevier Science B.V. All rights reserved.