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@PHDTHESIS{Qdemat:884845,
      author       = {Qdemat, Asma},
      title        = {{N}anoparticle assemblies: {O}rder by self-organization and
                      collective magnetism},
      volume       = {236},
      school       = {RWTH Aachen},
      type         = {Dissertation},
      address      = {Jülich},
      publisher    = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
      reportid     = {FZJ-2020-03282},
      isbn         = {978-3-95806-542-0},
      series       = {Schriften des Forschungszentrums Jülich. Reihe
                      Schlüsseltechnologien / Key Technologies},
      pages        = {xix, 282 S.},
      year         = {2021},
      note         = {Dissertation, RWTH Aachen, 2020},
      abstract     = {Assembly of nanoparticles into highly ordered two- or
                      three-dimensional arraysis a prerequisite to achieve their
                      application in novel functional devices. The unique
                      properties of such ensembles differ significantly from those
                      of individual nanoparticles. The assembly techniques have to
                      be able to control the arrangement of nanoparticles over
                      large areas and should be suitable for industrial
                      applications. In the present work, novel, simple and in
                      expensive assembly approaches used to achieve highly ordered
                      two- and three-dimensional arrangements of nanoparticles,
                      are presented. Also, an extensive determination of the
                      structural and the magnetic correlations of the obtained
                      systems has been performed using advanced scattering
                      methods. Among a variety of common assembly techniques,
                      drop-casting is one of the prospective approaches because of
                      its simplicity. Although drop casting has shown its
                      potential to form ordered nanoparticle arrangements, the
                      formation of uniform nanoparticle arrays over large areas
                      remains a challenging subject. Here, we introduce an
                      improved variant of the drop-casting method and demonstrate
                      the formation of large-area highly ordered monolayers of
                      silica nanospheres on asilicon substrate. In our method, the
                      addition of stearyl alcohol to the colloidal nanoparticle
                      dispersion assists the assembly of SiO$_{2}$ nanospheres
                      with a size of 50 nm into a highly ordered arrangement. We
                      reveal that the NPs concentration, the stearyl alcohol
                      concentration, the volume of the droplet, and the annealing
                      time are key factors in the self-assembly in our method. The
                      SiO$_{2}$ nanosphere monolayers contain almost no cracks and
                      voids. Structural characterization of the obtained silica NP
                      monolayer was done locally by Scanning Electron Microscopy
                      (SEM), and globally by X-Ray Reflectivity (XRR) and Grazing
                      Incidence Small-Angle X-ray Scattering (GISAXS), where the
                      data is reproduced by simulation within the Distorted Wave
                      Born Approximation (DWBA). This allows one to make unbiased
                      conclusions that the heat treatment in combination with a
                      compatible additive with a melting point significantly below
                      that of theparticles, can be a general method to improve the
                      ordering between particles inmonolayers as well as in
                      multilayers. Also, in this thesis, 2D arrays of cobalt
                      ferrite (COF) nanodots on silicon substrates were used to
                      determine the effects of dipolar interparticle interactions
                      on the magnetic properties of self- assembled structures of
                      magnetic nanoparticles. GISAXS and SEM confirm a
                      close-packed hexagonal order of the NP monolayer. Atomic
                      force microscopy (AFM) provides information about the
                      interparticle distance and XRR provides the depth profile of
                      the 2D nanodots monolayer. Simulation of the GISAXS pattern
                      reveals that the particles have a hemispherical shape with a
                      height of 10 nm, a radius of 8.5 nm and a hexagonal ...},
      cin          = {JCNS-2 / PGI-4 / JARA-FIT},
      cid          = {I:(DE-Juel1)JCNS-2-20110106 / I:(DE-Juel1)PGI-4-20110106 /
                      $I:(DE-82)080009_20140620$},
      pnm          = {899 - ohne Topic (POF4-899)},
      pid          = {G:(DE-HGF)POF4-899},
      experiment   = {EXP:(DE-MLZ)MARIA-20140101},
      typ          = {PUB:(DE-HGF)3 / PUB:(DE-HGF)11},
      urn          = {urn:nbn:de:0001-2021052765},
      url          = {https://juser.fz-juelich.de/record/884845},
}