Chlorine-NQR Relaxation Near the Structural Transitions of Natural and Deuterated (NH4)2TeCl6
Open Access
- 1 February 1992
- journal article
- Published by Walter de Gruyter GmbH in Zeitschrift für Naturforschung A
- Vol. 47 (1-2) , 261-264
- https://doi.org/10.1515/zna-1992-1-244
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 TeCl2 6- 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.Keywords
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