https://doi.org/10.1140/epjb/e20020062
X-ray scattering study of the phase transitions in crystalline fullerene-biphenyl C60[(C6H5)2]
1
Laboratoire de Physique des Solides (UMR CNRS 8502) , bâtiment 510,
Université Paris-Sud, 91405 Orsay, France
2
Centre de Recherche Paul Pascal, Université de Bordeaux I, avenue Schweitzer,
33600
Pessac, France
Corresponding author: a launois@lps.u-psud.fr
Received:
31
August
2001
Revised:
4
December
2001
Published online: 15 March 2002
The phase diagram of the newly synthesized mixed crystal C60-biphenyl is investigated as a function of temperature by single-crystal X-ray scattering. Diffuse scattering investigations evidencing complex disorder and local order effects are presented. Two phase transitions leading to two different doublings of the high temperature unit cell are observed, at 212 K and 147 K. The first transition is attributed to the ordering of twisted biphenyls, which couples to the orientational ordering of the C60 molecules as the temperature decreases. Full ordering of the C60 molecules is achieved below 100 K only, in the low temperature phase. The rich phase diagram of C60-biphenyl is due to the interplay between fullerene and biphenyl ordering phenomena.
PACS: 61.10.Eq – X-ray scattering (including small-angle scattering) / 61.10.Nz – Single-crystal and powder diffraction / 61.48.+c – Fullerenes and fullerene-related materials / 64.70.Kb – Solid-solid transitions
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2002