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@PHDTHESIS{Weber:917474,
      author       = {Weber, Moritz},
      title        = {{N}anoscale {U}nderstanding and {C}ontrol of {M}etal
                      {E}xsolution in {P}erovskite {O}xides},
      volume       = {596},
      school       = {RWTH Aachen University},
      type         = {Dissertation},
      address      = {Jülich},
      publisher    = {Forschungszentrum Jülich GmbH Zentralbibliothek Verlag},
      reportid     = {FZJ-2023-00687},
      isbn         = {978-3-95806-669-4},
      series       = {Schriften des Forschungszentrums Jülich Reihe Energie $\&$
                      Umwelt / Energy $\&$ Environment},
      pages        = {ix, 160},
      year         = {2022},
      note         = {Dissertation, RWTH Aachen University, 2022},
      abstract     = {The design of active and durable catalysts is a key
                      requirement for the development of efficient energy
                      conversion technologies urgently needed to meet the
                      challenges of global warming. Metal exsolution has attracted
                      much attention as an elegant synthesis route for
                      nanostructured perovskite catalysts. Thermal reduction of
                      the parent oxide induces the release of reducible cations
                      from the host phase, that assemble in the form of metallic
                      nanoparticles at the perovskite surface. To date the
                      atomistic processes that govern the exsolution behavior in
                      perovskites are inadequately understood. Here, the
                      compositional variety and structural complexity of
                      exsolution-active parent materials often complicate the
                      systematic investigation and comparison of the exsolution
                      response. This thesis investigates the exsolution of nickel
                      nanoparticles in Nb- and Ni- co-doped strontium titanate on
                      the basis of well-defined epitaxial thin film model systems.
                      The main issues addressed are the principles underlying the
                      accommodation of Ni dopants within the perovskite host
                      lattice, the influence of defects and surface
                      reconstructions on the exsolutionbehavior and most
                      importantly, the dynamics of metal exsolution processes and
                      the role of surface space charge regions for the exsolution
                      kinetics. A comprehensive study of the synthesis and
                      structural analysis of ceramic oxides and epitaxial thin
                      films forms the basis of this work. The characterization of
                      the exsolution behavior is based on the detailed analysis of
                      the surface morphology evolution upon thermal annealing at
                      low oxygen partial pressure, combined with methodologies for
                      the control of the sample defect structure, surface
                      chemistry and sample geometry. Furthermore, in-situ
                      diffraction and in-situ spectroscopy techniques have been
                      employed to study and disentangle the bulk and surface
                      material response of the perovskite during metal exsolution.
                      Collectively, the combined chemical, structural and
                      morphological investigations underreducing conditions reveal
                      strong surface limitations of metal exsolution. The surface
                      and bulk properties of the material response shows widely
                      different dynamics and appear to be mostly uncorrelated. In
                      accordance, the exsolution volume, i.e. the volume of the
                      selfassembledsurface nanoparticles is restricted to a small
                      fraction of the total amount of Ni present in the perovskite
                      bulk. In accordance surface properties were found to govern
                      the exsolution kinetics. In this context, space charge
                      regions at the perovskite surface have emerged to play a key
                      role for the process. The formation of space charge regions
                      was probed under oxidizing and reducing conditions by
                      in-situ spectroscopy, and found to be interrelated with the
                      exsolution dynamics. Based on the observations, a novel
                      model of the exsolution process as well as strategiesfor the
                      control of the metal exsolution behavior by surface
                      engineering is presented. Achieving control over the surface
                      properties of perovskites is pivotal for the rational design
                      of high-performance energy materials, where the concept of
                      metal exsolution opensnovel possibilities for the generation
                      of catalytic centers of high stability},
      cin          = {PGI-7},
      cid          = {I:(DE-Juel1)PGI-7-20110106},
      pnm          = {5233 - Memristive Materials and Devices (POF4-523) / 1231 -
                      Electrochemistry for Hydrogen (POF4-123)},
      pid          = {G:(DE-HGF)POF4-5233 / G:(DE-HGF)POF4-1231},
      typ          = {PUB:(DE-HGF)3 / PUB:(DE-HGF)11},
      url          = {https://juser.fz-juelich.de/record/917474},
}