H-1 NMR Relaxation Study of Molecular Motion in the Paraelectric Phase of (NH4)(2)Cd-2(SO4)(3) Single Crystals

The NMR spectrum and spin-lattice relaxation times, T, of the H-1 nuclei in (NH4)(2)Cd-2(SO4)(3) single crystals were obtained. The two minima in T, in the paraclectric phase are attributed to the reorientational motions of the NH4' groups. The H-1 T, of the (NH4)(2)Cd-2(SO4)(3) crystals can be described with BloembergenPurcell-Pound (BPP) theory. The experimental value of T, can be expressed in terms of an isotropic correlation time tau(H) for molecular motions by using the BPP theory, and determine the role of protons in these processes.