%0 Journal Article
%A Maus, Oliver
%A Agne, Matthias T.
%A Fuchs, Till
%A Till, Paul S.
%A Wankmiller, Björn
%A Gerdes, Josef Maximilian
%A Sharma, Rituraj
%A Heere, Michael
%A Jalarvo, Niina
%A Yaffe, Omer
%A Hansen, Michael Ryan
%A Zeier, Wolfgang G.
%T On the Discrepancy between Local and Average Structure in the Fast $Na^+$ Ionic Conductor $Na_{2.9}Sb_{0.9}W_{0.1}S_{4}$
%J Journal of the American Chemical Society
%V 145
%N 13
%@ 0002-7863
%C Washington, DC
%I ACS Publications
%M FZJ-2023-02065
%P 7147 - 7158
%D 2023
%X Aliovalent substitution is a common strategy to improve the ionic conductivity of solid electrolytes for solid-state batteries. The substitution of SbS43– by WS42– in Na2.9Sb0.9W0.1S4 leads to a very high ionic conductivity of 41 mS cm–1 at room temperature. While pristine Na3SbS4 crystallizes in a tetragonal structure, the substituted Na2.9Sb0.9W0.1S4 crystallizes in a cubic phase at room temperature based on its X-ray diffractogram. Here, we show by performing pair distribution function analyses and static single-pulse 121Sb NMR experiments that the short-range order of Na2.9Sb0.9W0.1S4 remains tetragonal despite the change in the Bragg diffraction pattern. Temperature-dependent Raman spectroscopy revealed that changed lattice dynamics due to the increased disorder in the Na+ substructure leads to dynamic sampling causing the discrepancy in local and average structure. While showing no differences in the local structure, compared to pristine Na3SbS4, quasi-elastic neutron scattering and solid-state 23Na nuclear magnetic resonance measurements revealed drastically improved Na+ diffusivity and decreased activation energies for Na2.9Sb0.9W0.1S4. The obtained diffusion coefficients are in very good agreement with theoretical values and long-range transport measured by impedance spectroscopy. This work demonstrates the importance of studying the local structure of ionic conductors to fully understand their transport mechanisms, a prerequisite for the development of faster ionic conductors.
%F PUB:(DE-HGF)16
%9 Journal Article
%$ 36946557
%U <Go to ISI:>//WOS:000967981500001
%R 10.1021/jacs.2c11803
%U https://juser.fz-juelich.de/record/1007410