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@ARTICLE{Newnham:1042708,
      author       = {Newnham, Jon A. and Kondek, Jędrzej and Hartel, Johannes
                      and Rosenbach, Carolin and Li, Cheng and Faka, Vasiliki and
                      Gronych, Lara and Glikman, Dana and Schreiner, Florian and
                      Wind, Domenik D. and Braunschweig, Björn and Hansen,
                      Michael Ryan and Zeier, Wolfgang G.},
      title        = {{C}orrelation between the {C}oherence {L}ength and {I}onic
                      {C}onductivity in ${L}i{N}b{OC}l_4$ via the {A}nion
                      {S}toichiometry},
      journal      = {Chemistry of materials},
      volume       = {37},
      number       = {11},
      issn         = {0897-4756},
      address      = {Washington, DC},
      publisher    = {American Chemical Society},
      reportid     = {FZJ-2025-02654},
      pages        = {4130-4144},
      year         = {2025},
      note         = {Bundesministerium für Bildung und Forschung (BMBF) funding
                      under the FESTBATT cluster of competence (project
                      03XP0430F)},
      abstract     = {$LiNbOCl_4$ is a recently reported material with high
                      $Li^+$ conductivities of ∼10 $mS·cm^{–1}$ at room
                      temperature. Here, we explore how changing the anion ratio
                      and the $Li^+$ content in the
                      $Li_{1–x}NbO_{1–x}Cl_{4+x}$ series (−0.4 ≤ x ≤
                      0.2) affects the ionic conductivity of the material. In
                      doing so, we find that the maximum coherence length and
                      ionic conductivity of $LiNbOCl_4$ are highly dependent on
                      the $O^{2–}$/$Cl^–$ anion ratio in the material.
                      Specifically, we show that, while an amorphous phase
                      fraction of $LiNbOCl_4$ remains constant throughout the
                      substitution series, any excess of $O^{2–}$ results in a
                      rapid decrease in the maximum coherence length of the
                      crystaline fraction in each sample. Through a combination of
                      diffraction and spectroscopic techniques, we show that this
                      occurs because the $O^{2–}$ anions cannot exist on the
                      terminal sites of the $[NbOCl_4]_∞^{–}$ chains in the
                      material, even when it is made with an excess of $O^{2–}$
                      resulting in a shortening of those chains. In contrast, it
                      was observed that $Cl^–$ can occupy the bridging sites
                      resulting in a dependence of the coherence length to the
                      anion ratio. As such, the ionic conductivity of $LiNbOCl_4$
                      can be maximized by controlling the maximum coherence length
                      in the material through the anion ratio. Notably, we
                      achieved high ionic conductivities for $LiNbOCl_4$
                      consistent with literature reports only when the material
                      was slightly $Li^+$ and $O^{2–}$ deficient, suggesting
                      that the literature samples may also have been
                      off-stoichiometry. In addition, we highlight the features
                      missing from the current structural models of $LiNbOCl_4$
                      including the presence of mixed $Cl^–$/$O^{2–}$ sites,
                      even in the stoichiometric material, which were previously
                      thought to not exist. Finally, we show that slightly
                      reducing the $Li^+$ and $O^{2–}$ contents in $LiNbOCl_4$
                      also translates to higher capacities when it is used as a
                      catholyte in solid-state batteries. These findings show the
                      importance of careful control of the stoichiometry in
                      $LiNbOCl_4$ to optimize its properties and highlights the
                      potential of $LiNbOCl_4$ for use as a catholyte in
                      solid-state batteries.},
      cin          = {IMD-4},
      ddc          = {540},
      cid          = {I:(DE-Juel1)IMD-4-20141217},
      pnm          = {1221 - Fundamentals and Materials (POF4-122)},
      pid          = {G:(DE-HGF)POF4-1221},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:001492363800001},
      doi          = {10.1021/acs.chemmater.5c00627},
      url          = {https://juser.fz-juelich.de/record/1042708},
}