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Main Title: Structural complexities and sodium-ion diffusion in the intercalates NaxTiS2: move it, change it, re-diffract it
Author(s): Wiedemann, Dennis
Suard, Emmanuelle
Lerch, Martin
Type: Article
Language Code: en
Abstract: After momentary attention as potential battery materials during the 1980s, sodium titanium disulphides, like the whole Na–Ti–S system, have only been investigated in a slapdash fashion. While they pop up in current reviews on the very subject time and again, little is known about their actual crystal-structural features and sodium-ion diffusion within them. Herein, we present a short summary of literature on the Na–Ti–S system, a new synthesis route to Na0.5TiS2-3R1, and results of high-temperature X-ray and neutron diffractometry on this polytype, which is stable for medium sodium content. Based thereon, we propose a revision of the crystal structure reported in earlier literature (missed inversion symmetry). Analyses of framework topology, probability-density functions, and maps of the scattering-length density reconstructed using maximum-entropy methods (all derived from neutron diffraction) reveal a honeycomb-like conduction pattern with linear pathways between adjacent sodium positions; one-particle potentials indicate associated activation barriers of ca. 0.1 eV or less. These findings are complemented by elemental analyses and comments on the high-temperature polytype Na0.9TiS2-2H. Our study helps to get a grip on structural complexity in the intercalates NaxTiS2, caused by the interplay of layer stacking and Na–Ti–vacancy ordering, and provides first experimental results on pathways and barriers of sodium-ion migration.
Issue Date: 3-Sep-2019
Date Available: 9-Sep-2019
DDC Class: 546 Anorganische Chemie
548 Kristallografie
Subject(s): neutron diffraction
sodium-ion conductor
one-particle potential
maximum entropy method
topological methods
Sponsor/Funder: DFG, 198634447, SPP 1613: Regenerativ erzeugte Brennstoffe durch lichtgetriebene Wasserspaltung: Aufklärung der Elementarprozesse und Umsetzungsperspektiven auf technologische Konzepte
EC/H2020/731096/EU/The Future of ILL 2030/FILL2030
Journal Title: RSC Advances : an international journal to further the chemical sciences
Publisher: Royal Society of Chemistry
Publisher Place: Cambridge
Volume: 9
Issue: 48
Publisher DOI: 10.1039/c9ra05690d
Page Start: 27780
Page End: 27788
EISSN: 2046-2069
Appears in Collections:FG Anorganische Chemie - Festkörper- und Materialchemie » Publications

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