POSSIBLE STRESS-INDUCED PHASE-TRANSITION IN O-TAS3

We have measured the stress-strain (sigma-epsilon) relations in o-TaS3 below the charge-density-wave (CDW) transition temperature. We find a large peak in d epsilon/d sigma at a critical stress sigma(c) approxi mate to 0.7 GPa below 200 K. The anomaly in d epsilon/d sigma, as larg e as 50% and perhaps associated with a change in length, is sample and temperature dependent. We show that this anomaly is associated with p reviously seen anomalies in the elastic and transport properties of Ta S3, and propose that there is a weakly first-order phase transition fr om one CDW phase to a different CDW phase at sigma(c).