Photoacoustic study of phase transition in graphite intercalation compound with SbCl/sub 5/

Photoacoustic (PA) effect was studied in graphite intercalation compounds with SbCl/sub 5/ under piezoelectric detection of PA signal. Highly-oriented pyrolytic graphite and disordered pyrolytic graphite were used as initial material. Temperature dependence of amplitude and phase of PA signal was studied in the interval 90-270 K. It has been found that in both types of samples the amplitude and phase have sharp extremum near 220 K, that is interpreted as due to a phase transition in GICs about this temperature. The numerical evaluations lead to conclusion that under piezoelectric detection the variation of volume on account of phase transition has main influence on formation of PA signal in region of phase transition.