The crystal structure of Na3InCl6 was determined at 200K by means of single-crystal X-ray analysis. The crystal belonged to a trigonal system in which an isolated InCl63− anion and 2 crystallographically non-equivalent Na ions Na(1) and Na(2) were confirmed. At 450K, however, the Rietveld analysis suggested that a new site was occupied by the Na ion forming vacancies at the original positions. In accordance with this observation, the 23Na nuclear magnetic resonance spectrum using a single crystal showed a coalescence phenomenon of the 2 crystallographically different peaks at around 400K. These observations supported dynamic chemical exchange between Na(1) and Na(2) through newly occupied Na(3) sites. Although the ionic conductivity for this compound was not very high (2 x 10−5S/cm at 500K), the conduction path for the Na ions could be clearly defined.

Conduction Path of the Sodium Ion in Na3InCl6 Studied by X-Ray Diffraction and 23Na and 115In NMR. K.Yamada, K.Kumano, T.Okuda: Solid State Ionics, 2005, 176[7-8], 823-9