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BY-NC-ND 3.0 license Open Access Published by De Gruyter June 2, 2014

Chlorine-NQR Relaxation Near the Structural Transitions of Natural and Deuterated (NH4)2TeCl6

  • C. Dimitropoulos , F. Borsa and J. Pelzl

Abstract

The temperature and isotope dependence of the 35,37Cl-NQR spin-lattice relaxation rate near the cubic to trigonal phase transition at Tc1 ≌ 87 K has been investigated in both (NH4) 2TeCl6 and (ND4)2TeCl6 salts. In the temperature range of ~ 20 K above and ~ 10 K below TCl, the relaxation obeys the relation (T1 • T)2 ∞(T-TCl). This behaviour corresponds to a direct relaxation mechanism in presence of a strongly damped rotational soft mode of the TeCl26- tetrahedra and is discussed on the basis of cation-anion coupling near the critical region. Below TCl we observe an extra contribution to the 35,37Cl relaxation rate which is tentatively ascribed to the dynamics of the NH4+ tetrahedra.

Received: 1991-7-27
Published Online: 2014-6-2
Published in Print: 1992-2-1

© 1946 – 2014: Verlag der Zeitschrift für Naturforschung

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

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