It was recalled that recent investigations of this 1:1 compound had indicated that both the rapid conduction of Na+ cations and the rapid reorientation of (Sn4)4- anions occurred in the -NaSn high-temperature solid phase. Nuclear magnetic resonance, involving 23Na and 119Sn, were used to monitor separately the motion of Na and Sn in the low-temperature ordered solid phase, -NaSn, where the correlation times of the motions were much longer. The motion of Na+ was evident in T1, T1, Ta2 and T2* (line-width) 23Na data for magnetic fields of 8 and 2T. The motion of Na could be described by a single time-constant, with thermal activation parameters of 9700K and 1.7 x 1014/s. The motion of Sn was evident in the T2, line-shape and stimulated echo data at 8T. The 119Sn stimulated echo data show unequivocally that the Sn motion involved the reorientation of Sn4 tetrahedra. Any diffusion of Sn between the tetrahedra was much slower. The combined T2 and stimulated echo data for 119Sn demonstrated that the Sn4 reorientation was thermally activated, with parameters of 13800K and 2.3 x 1015/s. The temperature dependence of the 119Sn T1-value was consistent with an activation energy of 7000K. The Sn T1-value was believed to be due to thermally-activated charge carriers.

R.D.Stoddard, M.S.Conradi, A.F.McDowell, M.L.Saboungi, D.L.Price: Physical Review B, 1995, 52[19], 13998-4005. See also: Journal of Non-Crystalline Solids, 1996, 205-207[1], 203-7