DOI: 10.1051/jp1:1996147
J. Phys. I France 6 (1996) 265-275

The Temperature Dependent Shear-Strain of the (NbSe ) I Compound, a Quasi-One-Dimensional Charge Density Wave System, below the Peierls Transition

Z. Vucic¹, J. Gladic², C. Haas¹ and J.L. De Boer<sup>1

1</sup>  University of Groningen, Laboratory of Chemical Physics, Materials Science Center, Nijenborgh 4, 9747 AG Groningen, The Netherlands
²  Institute of Physics of the University of Zagreb, Bijenicka cesta 46, P.O.B. 304, 10000 Zagreb, Croatia

(Received 19 July 1995, received in final form 24 October 1995, accepted 3 November 1995)

Abstract
An X-ray study of the quasi-one-dimensional charge density wave (CDW) system (NbS ₄) ₁₀I ₃ as a function of temperature from room temperature down to 130 K has been performed by taking oscillation and zeroth level Weissenberg photographs. A reversible transformation of the room temperature tetragonal lattice into four symmetrically-related monoclinic domains has been observed at the Peierls transition temperature, K, with a continuous change of the monoclinic angle from 90° to 92.1° at 130 K. The monoclinic deformation of the tetragonal lattice, i.e. the shear-strain along the chain axis seems to be an elastic response to the long wavelength transverse modulation of the 3D-CDW order which can be qualitatively explained by taking into account the Coulomb interaction between CDWs on neighbouring chains up to the next-nearest-neighbours.

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