| Institution: | 1. Christian-Albrecht University of Kiel, Institute of Inorganic Chemistry, Max-Eyth-Straße 2, 24118 Kiel, Germany
These authors contributed equally to this work.;2. Christian-Albrecht University of Kiel, Institute of Inorganic Chemistry, Max-Eyth-Straße 2, 24118 Kiel, Germany;3. Karlsruhe Institute of Technology, Institute of Applied Materials, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany |
| Abstract: | The new thiostannate Na4Sn2S6 was prepared by directed crystal water removal from the hydrate Na4Sn2S6 ⋅ 5H2O at moderate temperatures. While the structure of the hydrate comprises isolated Sn2S6]4− anions, that of the anhydrate contains linear chains composed of corner-sharing SnS4 tetrahedra, a structural motif not known in thiostannate chemistry. This structural rearrangement requires bond-breakage in the Sn2S6]4− anion, movements of the fragments of the opened Sn2S6]4− anion and Sn−S−Sn bond formation. Simultaneously, the coordination environment of the Na+ cations is significantly altered and the in situ formed NaS5 polyhedra are joined by corner- and edge-sharing to form a six-membered ring. Time-dependent in situ X-ray powder diffraction evidences very fast rehydration into Na4Sn2S6 ⋅ 5H2O during storage in air atmosphere, but recovery of the initial crystallinity requires several days. Impedance spectroscopy demonstrates a mediocre room-temperature Na+ ion conductivity of 0.31 μS cm−1 and an activation energy for ionic transport of Ea=0.75 eV. |
