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@ARTICLE{Gries:841856,
      author       = {Gries, U. N. and Schraknepper, H. and Skaja, K. and Gunkel,
                      F. and Hoffmann-Eifert, S. and Waser, R. and De Souza, R.
                      A.},
      title        = {{A} {SIMS} study of cation and anion diffusion in tantalum
                      oxide},
      journal      = {Physical chemistry, chemical physics},
      volume       = {20},
      number       = {2},
      issn         = {1463-9084},
      address      = {Cambridge},
      publisher    = {RSC Publ.},
      reportid     = {FZJ-2018-00154},
      pages        = {989 - 996},
      year         = {2018},
      abstract     = {Ion transport in ceramics of the low-temperature phase of
                      tantalum pentoxide, L-Ta2O5, was examined by means of
                      diffusion experiments and subsequent analysis of diffusion
                      profiles with time-of-flight secondary ion mass spectrometry
                      (ToF-SIMS). 18O/16O isotope anneals were used to investigate
                      oxygen diffusion, and oxygen tracer diffusion coefficients
                      were obtained for the temperature range of 623 ≤ T/K ≤
                      873 at an oxygen partial pressure of pO2 = 0.2 bar and for
                      the oxygen partial pressure range of 10−2 ≤ pO2/bar ≤
                      100 at a temperature of T = 723 K. Cation diffusion in Ta2O5
                      was probed by using chemically similar niobium as the
                      diffusant (in the absence of stable tantalum isotopes). Thin
                      films of Nb2O5 were deposited onto Ta2O5 ceramics; diffusion
                      anneals yielded niobium diffusion coefficients for the
                      temperature range of 1073 ≤ T/K ≤ 1223 at an oxygen
                      partial pressure of pO2 = 0.2 bar. Comparison of the
                      measured diffusion coefficients strongly suggests that
                      oxygen is many orders of magnitude more mobile than niobium
                      in L-Ta2O5 at these temperatures and at pO2 = 0.2 bar. The
                      electrical conductivity was also determined in the range 950
                      ≤ T/K ≤ 1200 and 10−23 ≤ pO2/bar ≤ 10−2.
                      Considered together with the measured diffusion
                      coefficients, the conductivity data indicate that under
                      oxidising conditions conduction is due to oxygen ions above
                      T = 1090–1130 K and due to electron holes below this
                      temperature range. Point-defect models are presented that
                      are consistent with these transport data and with
                      conductivity data in the literature. They suggest that under
                      oxidising conditions oxygen interstitials are the majority
                      ionic charge carriers in L-Ta2O5. The implications for
                      resistive switching devices are discussed.},
      cin          = {PGI-7 / JARA-FIT},
      ddc          = {540},
      cid          = {I:(DE-Juel1)PGI-7-20110106 / $I:(DE-82)080009_20140620$},
      pnm          = {524 - Controlling Collective States (POF3-524)},
      pid          = {G:(DE-HGF)POF3-524},
      typ          = {PUB:(DE-HGF)16},
      pubmed       = {pmid:29234759},
      UT           = {WOS:000419219700029},
      doi          = {10.1039/C7CP07441G},
      url          = {https://juser.fz-juelich.de/record/841856},
}