We present differential-scanning-calorimetry curves and infrared spectra taken during the temperature cycling of stoichiometrically pure RbC60 powder. In addition to the three known phases (high-temperature fcc, ortho-I, and ortho-II), we see evidence for an intermediate structure around 300 K, observed previously by ESR and x-ray diffraction. This phase is obtained both by quenching from high temperature and by warming up the ortho-II structure. Its infrared spectrum is identical to that of the high-temperature fcc phase, indicating a structure containing C60- monomers.
ASJC Scopus subject areas
- Condensed Matter Physics