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@ARTICLE{Naqash:878681,
      author       = {Naqash, Sahir and Tietz, Frank and Yazhenskikh, Elena and
                      Müller, Michael and Guillon, Olivier},
      title        = {{I}mpact of sodium excess on electrical conductivity of
                      {N}a3{Z}r2{S}i2{PO}12 + x {N}a2{O} ceramics},
      journal      = {Solid state ionics},
      volume       = {336},
      issn         = {0167-2738},
      address      = {Amsterdam [u.a.]},
      publisher    = {Elsevier Science},
      reportid     = {FZJ-2020-02999},
      pages        = {57-66},
      year         = {2019},
      abstract     = {In order to industrialize NaSICON materials, modern
                      fabrication techniques have to be used and one of those
                      techniques for producing large-scale electrolyte sheets with
                      10–300 μm thickness is tape casting. Such technique
                      however requires a sintering step at high temperatures
                      leading to sodium depletion due to evaporation. The sodium
                      loss becomes more significant for large-area and thin
                      components. In order to investigate and compensate the
                      sodium loss, NaSICON compositions with sodium excess were
                      prepared, i.e. Na3Zr2Si2PO12 + x Na2O
                      (0 ≤ x ≤ 0.2). The sodium loss can be reduced by
                      applying a two-step sintering process (1250 °C for only
                      0.5 h and then at 1230 °C for 5 h). Several
                      characterization techniques were used to analyze the
                      resulting ceramics, the sodium depletion and its consequence
                      on electrical conductivity. Chemical analyses indicated that
                      all compositions were sodium deficient. Furthermore, the
                      weight loss was investigated by thermogravimetric analysis
                      confirming the reduction of weight loss by a factor 2 by
                      applying a two-step sintering procedure with lower second
                      sintering temperature. Initial thermodynamic calculations of
                      the phase equilibria at high temperatures confirm the
                      predominant evaporation of sodium. The highest electrical
                      conductivity (1.6 ⋅ 10−3 S cm−1 at 25 °C) was
                      measured for the composition showing the least sodium
                      deficiency (x = 0.2). Furthermore, the activation energy
                      of bulk and grain boundary conductivity decreased with
                      increasing x in system.},
      cin          = {IEK-1 / JARA-ENERGY / IEK-12 / IEK-2},
      ddc          = {530},
      cid          = {I:(DE-Juel1)IEK-1-20101013 / $I:(DE-82)080011_20140620$ /
                      I:(DE-Juel1)IEK-12-20141217 / I:(DE-Juel1)IEK-2-20101013},
      pnm          = {131 - Electrochemical Storage (POF3-131) / 113 - Methods
                      and Concepts for Material Development (POF3-113)},
      pid          = {G:(DE-HGF)POF3-131 / G:(DE-HGF)POF3-113},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000470951300008},
      doi          = {10.1016/j.ssi.2019.03.017},
      url          = {https://juser.fz-juelich.de/record/878681},
}