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@ARTICLE{Mueller:878685,
      author       = {Mueller, Michael P. and Pingen, Katrin and Hardtdegen,
                      Alexander and Aussen, Stephan and Kindsmueller, Andreas and
                      Hoffmann-Eifert, Susanne and De Souza, Roger A.},
      title        = {{C}ation diffusion in polycrystalline thin films of
                      monoclinic {H}f{O} 2 deposited by atomic layer deposition},
      journal      = {APL materials},
      volume       = {8},
      number       = {8},
      issn         = {2166-532X},
      address      = {Melville, NY},
      publisher    = {AIP Publ.},
      reportid     = {FZJ-2020-03003},
      pages        = {081104 -},
      year         = {2020},
      abstract     = {Though present in small amounts and migrating at low rates,
                      intrinsic cation defects play a central role in governing
                      the operational lifetime of oxide-ion conducting materials
                      through slow degradation processes such as interdiffusion,
                      kinetic demixing, grain growth, and creep. In this study, a
                      new experimental approach to characterizing the behavior of
                      such slow-moving, minority defects is presented. Diffusion
                      is probed in samples with a constant cation-defect
                      concentration well above the equilibrium values. This
                      approach is applied to monoclinic hafnium dioxide, m-HfO2.
                      To this end, nanocrystalline thin films of m-HfO2 were
                      prepared by atomic layer deposition. Diffusion experiments
                      with ZrO2 as a diffusion source were performed in the
                      temperature range 1173 ≤ T/K ≤ 1323 in air. The Zr
                      diffusion profiles obtained subsequently by secondary ion
                      mass spectrometry exhibited the following two features: the
                      first feature was attributed to slow bulk diffusion and the
                      second was attributed to combined fast grain-boundary
                      diffusion and slow bulk diffusion. The activation enthalpy
                      of Zr diffusion in bulk HfO2 was found to be (2.1 ± 0.2)
                      eV. This result is consistent with the
                      density-functional-theory calculations of hafnium-vacancy
                      migration in m-HfO2, which yield values of ∼2 eV for a
                      specific path. The activation enthalpy of the grain-boundary
                      diffusion of (2.1 ± 0.3) eV is equal to that for bulk
                      diffusion. This behavior is interpreted in terms of enhanced
                      cation diffusion along space-charge layers},
      cin          = {PGI-7 / PGI-10 / JARA-FIT},
      ddc          = {600},
      cid          = {I:(DE-Juel1)PGI-7-20110106 / I:(DE-Juel1)PGI-10-20170113 /
                      $I:(DE-82)080009_20140620$},
      pnm          = {524 - Controlling Collective States (POF3-524)},
      pid          = {G:(DE-HGF)POF3-524},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000560032100002},
      doi          = {10.1063/5.0013965},
      url          = {https://juser.fz-juelich.de/record/878685},
}