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@ARTICLE{Redhammer:903602,
      author       = {Redhammer, Günther J. and Badami, Pavan and Meven, Martin
                      and Ganschow, Steffen and Berendts, Stefan and Tippelt,
                      Gerold and Rettenwander, Daniel},
      title        = {{W}et-{E}nvironment-{I}nduced {S}tructural {A}lterations in
                      {S}ingle- and {P}olycrystalline {LLZTO} {S}olid
                      {E}lectrolytes {S}tudied by {D}iffraction {T}echniques},
      journal      = {ACS applied materials $\&$ interfaces},
      volume       = {13},
      number       = {1},
      issn         = {1944-8244},
      address      = {Washington, DC},
      publisher    = {Soc.},
      reportid     = {FZJ-2021-05256},
      pages        = {350 - 359},
      year         = {2021},
      abstract     = {Li7La3Zr2O12 (LLZO) is one of the potential candidates for
                      Li metal-based solid-state batteries owing to its high Li+
                      conductivity (≈10$^{–3}$ S cm$^{–1}$) at room
                      temperature and large electrochemical stability window.
                      However, LLZO undergoes protonation under the influence of
                      moisture-forming Li2CO3 layers, thereby affecting its
                      structural and transport properties. Therefore, a detailed
                      understanding on the impact of the exchange of H+ on Li+
                      sites on structural alteration and kinetics under the
                      influence of wet environments is of great importance. The
                      present study focuses on the Li+/H+ exchange in
                      single-crystal and polycrystal Li6La3ZrTaO12 (LLZTO) garnets
                      prepared using the Czochralski method and solid-state
                      reactions subjected to weathering in air, aqueous solutions
                      at room temperature, and in aqueous solution at 363 K using
                      X-ray diffraction (XRD) and neutron diffraction (ND)
                      techniques. Based on 36 single-crystal diffraction and 88
                      powder diffraction measurements, we found that LLZTO
                      crystallizes with space group (SG) Ia3̅d with Li located in
                      96h (Li(2)) and 24d (Li(1)) sites, whereas the latter one is
                      displaced toward the general position 96h forming shorter
                      Li(1)–Li(2) jump distances. The degradation in air, wet
                      air, water, and acetic acid leads to a Li+/H+ exchange that
                      preferably takes place at the 24d site, which is in contrast
                      to previous reports. Higher Li+/H+ was observed for LLZTO
                      aged in water at 363 K that reduced the symmetry to SG
                      I4̅3d from SG Ia3̅d. This symmetry reduction was found to
                      be related to the site occupation behavior of Li at the
                      tetrahedral 12a site in SG I4̅3d. Moreover, Li+ is
                      exchanged by H+ preferably at the 48e site (equivalent to
                      96h site). We also found that the equilibrium H+
                      concentrations in all media tested remains very similar,
                      which is related to the H+ diffusion in the LLZTO-controlled
                      exchange process. Only the increase in temperature led to a
                      significant increase in the exchange capacity as well as in
                      the Li+/H+ exchange rate. Overall, we found that the
                      exchange rate, exchange capacity, site occupation behavior
                      of Li+ and H+, as well as the structural stability of LLZTO,
                      strongly depend on the composition. These findings suggest
                      that measurements on a single LLZTO variant sample do not
                      lead to a general conclusion for all garnets to guide the
                      field toward better materials. In contrast, each composition
                      has to be analyzed exclusively to understand the interplay
                      of composition, structure, and exchange kinetic properties.},
      cin          = {JCNS-FRM-II / MLZ / JARA-FIT / JCNS-2},
      ddc          = {600},
      cid          = {I:(DE-Juel1)JCNS-FRM-II-20110218 / I:(DE-588b)4597118-3 /
                      $I:(DE-82)080009_20140620$ / I:(DE-Juel1)JCNS-2-20110106},
      pnm          = {6G4 - Jülich Centre for Neutron Research (JCNS) (FZJ)
                      (POF4-6G4)},
      pid          = {G:(DE-HGF)POF4-6G4},
      experiment   = {EXP:(DE-MLZ)HEIDI-20140101},
      typ          = {PUB:(DE-HGF)16},
      pubmed       = {33372519},
      UT           = {WOS:000611066000030},
      doi          = {10.1021/acsami.0c16016},
      url          = {https://juser.fz-juelich.de/record/903602},
}