X-Ray Study of Glassy Behavior in C₆₀Single Crystals

Abstract

We observed the relaxation behavior of the X-ray diffraction intensity arising from the glassy phase transition in C 60 single crystals for the first time. The (7 10 0) reflection which appeared below about 160 K showed an anomalous cusp-type feature near 90 K. It was found that this behavior strongly depended on the cooling rate of the specimen. Intensity relaxation of the reflection at 80 K at a cooling rate of 66 mK/s followed the single exponential law, I ( t )∝ I 0 (1-exp (- t /τ)) with a relaxation time constant τ of 1.8×10 4 seconds. These results strongly support those previously reported.