DOI: 10.1051/jp1:1993255
J. Phys. I France 3 (1993) 2437-2449

³⁵Cl NQR and calorimetric reinvestigation of the incommensurate phase of bis(4-chlorophenyl) sulfone : evidence for no lock-in transition

J. Etrillard¹, B. Toudic¹, M. Bertault¹, J. Even¹, M. Gourdji², A. Péneau² and L. Guibé<sup>2

1</sup>  Groupe Matière Condensée et Matériaux, U.R.A. au C.N.R.S. 040804, Université de Rennes I, Bâtiment B11, Campus de Beaulieu, 35042 Rennes Cedex, France
²  Institut d'Electronique Fondamentale, U.R.A. au C.N.R.S. 0022, Université Paris XI, Bâtiment 220, 91405 Orsay Cedex, France

(Received 8 March 1993, accepted in final form 3 August 1993)

Abstract
³⁵Cl NQR and calorimetric measurements in BCPS have been reinvestigated between 77 K and room temperature (NQR) and between 100 K and 180 K ( ). It is shown that, in contradiction with conclusions found in literature, there is no lock-in transition at 115 K. These new results are in agreement with those obtained with other experimental techniques: Raman scattering, X-ray diffraction, neutron diffraction and proton NMR; the latter indicate that the incommensurate phase, appearing on cooling at 150 K, persists down to 4.2 K, at least. The shape of the ³⁵Cl NQR spectrum in the BCPS incommensurate phase shows that the frequency of a chlorine nucleus is a function of the order parameter, through linear and quadratic terms.

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