Anomalies in the microwave conductivity of a polycrystalline C60 membrane

A study is reported of an anomaly in che microwave conductivity of a polycrystalline C-60 membrane at T-c=260 K (the transition width is 30 K). Raman scattering measurements indicate that the sample is the C-60 fullerite without any signs of graphitization, amorphous phase, or the presence of C-70 and that the detected microwave conductivity jump can be unambiguously identified as due to the C-60 phase. (C) 1998 American Institute of Physics. [S1063-7834(98)04003-9].