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@ARTICLE{Sharma:867204,
      author       = {Sharma, Monika and Gupta, Mukul and Kaghazchi, Payam and
                      Murugavel, Sevi},
      title        = {{S}ize induced structural changes in maricite-{N}a{F}e{PO}
                      4 : an in-depth study by experiment and simulations},
      journal      = {Physical chemistry, chemical physics},
      volume       = {21},
      number       = {45},
      issn         = {1463-9084},
      address      = {Cambridge},
      publisher    = {RSC Publ.},
      reportid     = {FZJ-2019-06021},
      pages        = {25206 - 25214},
      year         = {2019},
      abstract     = {Rechargeable batteries based on the most abundant elements,
                      such as sodium and iron, have a great potential in the
                      development of cost effective sodium ion batteries for large
                      scale energy storage devices. We report, for the first time,
                      crystallite size dependent structural investigations on
                      maricite-NaFePO4 through X-ray diffraction, X-ray absorption
                      spectroscopy and theoretical simulations. Rietveld
                      refinement analysis on the X-ray diffraction data reveals
                      that a decrease in the unit cell parameters leads to volume
                      contraction upon reduction in the crystallite size. Further,
                      the atomic multiplet simulations on X-ray absorption spectra
                      provide unequivocally a change in the site symmetry of
                      transition metal ions. The high resolution oxygen K-edge
                      spectra reveal a substantial change in the bonding character
                      with the reduction of crystallite size, which is the
                      fundamental cause for the change in the unit cell parameters
                      of maricite-NaFePO4. In parallel, we performed
                      first-principles density functional theory (DFT)
                      calculations on maricite-NaFePO4 with different sodium ion
                      vacancy concentrations. The obtained structural parameters
                      are in excellent agreement with the experimental
                      observations on the mesostructured maricite-NaFePO4. The
                      volumetric changes with respect to crystallite size are
                      related to the compressive strain, resulting in the
                      improvement in the electronic diffusivity. The
                      nano-crystalline maricite-NaFePO4 with improved kinetics
                      will open a new avenue for its usage as a cathode material
                      in sodium ion batteries.},
      cin          = {IEK-1},
      ddc          = {540},
      cid          = {I:(DE-Juel1)IEK-1-20101013},
      pnm          = {131 - Electrochemical Storage (POF3-131)},
      pid          = {G:(DE-HGF)POF3-131},
      typ          = {PUB:(DE-HGF)16},
      pubmed       = {pmid:31696889},
      UT           = {WOS:000506841300033},
      doi          = {10.1039/C9CP03838H},
      url          = {https://juser.fz-juelich.de/record/867204},
}