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@PHDTHESIS{Ji:867906,
author = {Ji, Wenhai},
title = {{T}he guided self-assembly of magnetic nanoparticles into
two- and three-dimensional nanostructures using patterned
substrates},
volume = {214},
school = {RWTH Aachen},
type = {Dr.},
address = {Jülich},
publisher = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
reportid = {FZJ-2019-06505},
isbn = {978-3-95806-462-1},
series = {Schriften des Forschungszentrums Jülich. Reihe
Schlüsseltechnologien / Key Technologies},
pages = {VI, 140 S.},
year = {2019},
note = {RWTH Aachen, Diss., 2019},
abstract = {The present thesis provides an original and extensive
contribution to the understanding of the self-assembly of
magnetic nanoparticles in different dimensions with the help
of patterned sapphire substrates and block copolymers. The
combination of real space and reciprocal space techniques
allows a better understanding of nanostructures with
different dimensions, which are formed on the patterned
substrates. The first topic covered in the thesis is
formation of 2D nanoparticle assemblies by annealing the
M-plane sapphire at various temperatures. The procedure is
adjusted to obtain patterned substrates that can accommodate
the nanoparticles of a given size. The highly-ordered 2D
magnetic nanoparticles arrays deposited on patterned
sapphire substrates were studied using scanning electron
microscopy and grazing incidence x-ray scattering (GISAXS)
methods. In addition, a detailed analysis of GISAXS data
using the Distorted Wave Born Approximation theory allowed
characterizing the samples quantitatively. The second topic
is to deal with the self-organization of 3D nanoparticles
assemblies over the macroscopic scale, with precise control
of the spatial organization of nanoparticles by employing
the block copolymers. It was achieved by controlling the
morphology of the block copolymer films with a solvent vapor
annealing, which proved to be a powerful method. It was
demonstrated that the solvent volume, annealing time and
drying process had an impact on the final morphology of the
nanocomposite film. The influence of those parameters was
thoroughly investigated and optimum values were derived. The
orientation parameter obtained from GISAXS measurements
allows identifying the different stages of the alignment of
the block copolymer matrix. Using developed approach, 3D
nanoparticles with a long-range order in nanocomposite film
can be readily obtained on patterned substrates, which were
confirmed by both atomic force microcopy and GISAXS methods.
The magnetic interactions between magnetic nanoparticles in
nanocomposite film, containing only 8 wt $\%$ of
nanoparticles were studied with polarized neutron scattering
experiments. The qualitative analysis of the grazing
incidence neutron scattering and polarized neutron
reflectometry data, combined with GISAXS data analysis,
unambiguously demonstrated that a weak magnetic scattering
from array of magnetic nanoparticles can be detected. The
methodology developed in this work exemplifies a key role of
polarized neutron scattering techniques in characterization
of magnetic inter-particle interactions embedded in complex
nanocomposite materials. In conclusion, this work shows how
2D and 3D nanoparticles assemblies can be prepared by using
patterned substrates and how preparation parameters affect
the resulting nanostructures. The vital role of various
scattering methods in qualitative characterization of
structural and magnetic properties of nanostructures was
emphasized.},
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 = {144 - Controlling Collective States (POF3-144) / 524 -
Controlling Collective States (POF3-524) / 6212 - Quantum
Condensed Matter: Magnetism, Superconductivity (POF3-621) /
6213 - Materials and Processes for Energy and Transport
Technologies (POF3-621) / 6G4 - Jülich Centre for Neutron
Research (JCNS) (POF3-623)},
pid = {G:(DE-HGF)POF3-144 / G:(DE-HGF)POF3-524 /
G:(DE-HGF)POF3-6212 / G:(DE-HGF)POF3-6213 /
G:(DE-HGF)POF3-6G4},
experiment = {EXP:(DE-MLZ)MARIA-20140101 / EXP:(DE-MLZ)KWS1-20140101 /
EXP:(DE-MLZ)KWS3-20140101},
typ = {PUB:(DE-HGF)3 / PUB:(DE-HGF)11},
urn = {urn:nbn:de:0001-2020072205},
url = {https://juser.fz-juelich.de/record/867906},
}