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@ARTICLE{Shiratori:61312,
      author       = {Shiratori, Y. and Magrez, A. and Fischer, W. and Pithan, C.
                      and Waser, R.},
      title        = {{T}emperature-induced phase transitions in micro- submicro-
                      and nanocrystalline {N}a{N}b{O}3},
      journal      = {The journal of physical chemistry / C},
      volume       = {111},
      issn         = {1932-7447},
      address      = {Washington, DC},
      publisher    = {Soc.},
      reportid     = {PreJuSER-61312},
      pages        = {18493},
      year         = {2007},
      note         = {Record converted from VDB: 12.11.2012},
      abstract     = {Phase transitions in micro-, submicro-, and nanocrystalline
                      NaNbO3 were investigated by temperature-tuning Raman
                      spectroscopy and X-ray powder diffraction method. Three
                      powders with different average particle size showed
                      successive phase transitions within the measured temperature
                      range from -150 to 450 degrees C. The temperature
                      characteristics of Raman active phonons in
                      n-ticrocrystalline NaNbO3 corresponded the one reported for
                      bulk NaNbO3, which transforms with increasing temperature
                      from the ferroelectric N into the antiferroelectric P phase
                      and finally above 373 degrees C (T-s3) into the
                      antiferroeletric R phase. Submicrocrystalline NaNbO3, which
                      takes the noncentrosymmetric orthorhombic Pmc2(1) structure
                      at room temperature, transformed into a pseudocubic
                      structure at 333 degrees C (TO). Nanocrystalline NaNbO3
                      showed a diffused phase transition from an orthorhombic Pmma
                      structure to a high-temperature phase at around 180 degrees
                      C (T-s2). For micro- and submicrocrystalline NaNbO3,
                      hysteretic phase transition behavior was found for the
                      temperature characteristics of specific phonons. On the
                      other hand, the characteristics obtained for nanocrystalline
                      NaNbO3 were much more diffused and did not show any
                      hysteretic effect. Crystal structure refinements of the
                      X-ray powder diffraction patterns using the Rietveld method
                      demonstrated a hysteretic deformation of the a-b plane for
                      microcrystalline NaNbO3 around T-3 and of the b-c plane for
                      submicrocrystalline NaNbO3 around T-s3. The temperature
                      dependence of the primitive perovskite volumes showed a very
                      small hysteresis for microcrystalline NaNbO3 but a clear one
                      for submicrocrystalline NaNbO3. Lattice distortion of the
                      submicrocrystalline Pmc2(1) structure from a cubic
                      perovskite lattice induced a particularly large contraction
                      of parameter c around T-s3 with increasing temperature,
                      which resulted in a decrease of the primitive cell volume.
                      This transition showed a first-order type character, which
                      may relate to a ferroelectric-antiferroelectric transition.
                      Rearrangement of the NbO6 octahedra induces a transition
                      from an orthorhombic into a pseudocubic structure.},
      keywords     = {J (WoSType)},
      cin          = {IFF-6 / JARA-FIT},
      ddc          = {540},
      cid          = {I:(DE-Juel1)VDB786 / $I:(DE-82)080009_20140620$},
      pnm          = {Kondensierte Materie},
      pid          = {G:(DE-Juel1)FUEK414},
      shelfmark    = {Chemistry, Physical / Nanoscience $\&$ Nanotechnology /
                      Materials Science, Multidisciplinary},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000251615500008},
      doi          = {10.1021/jp0738053},
      url          = {https://juser.fz-juelich.de/record/61312},
}