Effects of irradiation on elastic properties ofTaS3

Elastic properties associated with the charge-density wave in orthorhombic ${\mathrm{TaS}}_3$ were studied as functions of density of pinning centers. The pins were introduced by electron irradiation. The softening of the Young’s modulus at temperatures near the Peierls temperature $T_P$, the softening for electric fields above the threshold field, and the accompanying internal friction phenomena were independent of pin density for irradiation levels below about ${10}^{18}$ electrons/${\mathrm{cm}}^2$ (sufficient to raise the threshold field by an order of magnitude). For larger pin densities the features in modulus and friction near $T_P$ broadened and became smaller.