Structure and ionic conductivity of halocomplexes of main group metallic elements studied by NMR and NQR

Li3InBr6 Undergoes phase transition to a lithium superionic conductor at T-tr = 314 K (sigma = 5.0 x 10(-4) S cm(-1) at 330 K). The Rietveld analysis and the DSC measurement suggested that the positional disorder is introduced at the cationic sites above T-tr. The X-ray powder diffraction pattern at the superionic phase changes gradually with temperature and finally shows a simple powder pattern at 420 K which is quite similar to that of LiBr. This rock salt structure contains intrinsic vacancies because One In3+ and two vacancies substitute for three Li+. Li-7 and In-115 NMR support the rapid diffusion of the Li+ and the introduction of the In3+ into the rock salt structure. On the other hand, the ionic conductivity for Na3InCl6 was 10(-5) cm(-1) even at 500 K. Conduction path for the sodium ions could be proposed by means of the Rietveld analysis and the NMR experiment using a single crystal.