Coupling of the lattice and superlattice deformations and hysteresis in thermal expansion for the quasi-one-dimensional conductor TaS3.

An original interferometer-based setup for measurements of length of needlelike samples is developed, and thermal expansion of o-TaS(3) crystals is studied. Below the Peierls transition the temperature hysteresis of length L is observed, the width of the hysteresis loop deltaL/L being up to 5 x 10(-5). The behavior of the loop is anomalous: the length changes so that it is in front of its equilibrium value. The hysteresis loop couples with that of conductivity. With lowering the temperature down to 100 K the charge-density waves' elastic modulus grows achieving a value comparable with the lattice Young modulus. Our results could be helpful in consideration of different systems with intrinsic superstructures.