It was recalled that recent investigations of this Zintl compound had shown that both the rapid conduction of Na+ ions and the rapid re-orientation of (Sn4)4- sub-units occurred in the high-temperature  phase. Here, 23Na and 119Sn nuclear magnetic resonance techniques were used to monitor the motion of Na and Sn in the low-temperature  phase, where the mobility was lower. It was found that the motion of 23Na could be described by using a single activated time constant with an E/k ratio of 9700K and an attempt frequency of 1.7 x 1014/s. The motion of Sn was evident in the 119Sn data; thus showing that the motion of Sn was thermally activated, with an E/k ratio of 13800K and an attempt frequency of 2.3 x 1015/s. The 119Sn stimulated-echo data also demonstrated that the Sn motion involved the reorientation of Sn4 tetrahedra. The Sn diffusion between different tetrahedra was much slower.

R.D.Stoddard, M.S.Conradi, A.F.McDowell, M.L.Saboungi, D.L.Price: Journal of Non-Crystalline Solids, 1996, 205-207[1], 203-7