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@PHDTHESIS{Silva:857740,
      author       = {Silva, Rafael},
      title        = {{M}icrostructure and {T}hermomechanical {P}roperties of
                      {S}r{T}i$_{1-x}${F}e$_{x}${O}$_{3-δ}$ {O}xygen {T}ransport
                      {M}embranes and {S}upports},
      volume       = {450},
      school       = {RWTH Aachen},
      type         = {Dr.},
      address      = {Jülich},
      publisher    = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
      reportid     = {FZJ-2018-06708},
      isbn         = {978-3-95806-381-5},
      series       = {Schriften des Forschungszentrums Jülich Reihe Energie $\&$
                      Umwelt / Energy $\&$ Environment},
      pages        = {vi, 148 S.},
      year         = {2019},
      note         = {RWTH Aachen, Diss., 2018},
      abstract     = {Pure oxygen is considered to be an important commodity and
                      its demand is expected to rise in the upcoming years.
                      Therefore, interest in a new, scalable technology for air
                      separation based on oxygen transport membranes has
                      increased. Indeed, ceramic oxygen transport membranes can
                      possess remarkable advantages compared to existing
                      state-of-the-art processes for oxygen production in small
                      and medium scale. Typically, such membranes have to be
                      operated at 800 - 900 °C and under high pressure gradients,
                      which challenges significantly the chemical and mechanical
                      stability of the respective brittle ceramics components.
                      Thus, the current work concentrates on the mechanical
                      properties of a promising perovskite material for mixed
                      conducting oxygen transport membranes based on
                      SrTi$_{1-x}$Fe$_{x}$O$_{3-\delta}$, (STF-X) with x = 0.25,
                      0.35 and 0.5. The dense membrane materials, synthesized
                      through solid state reaction route and processed via tape
                      casting, were characterized with respect to their mechanical
                      behavior via depth-sensitive indentation testing and
                      ring-on-ring flexural tests. No tradeoff between functional
                      and mechanical properties is observed for the studied dense
                      materials. Ring-on-ring tests conducted at different loading
                      rates gave access to subcritical crack growth sensitivity
                      and aided the prediction of the materials’ lifetime
                      through stress-time-probability diagrams, where
                      SrTi$_{0.65}$Fe$_{0.35}$O$_{3}$ revealed the best
                      performance among the studied compositions. The mechanical
                      properties of dense tape cast
                      SrTi$_{0.75}$Fe$_{0.25}$O$_{3-\delta}$ were derived at
                      900°C with help of ring-on-ring flexural tests carried out
                      at two distinct loading rates: 1 and 100 N/min. The apparent
                      elastic modulus appeared to be time dependent. The average
                      fracture stress estimated on the basis of the data was
                      rather loading rate invariant and higher than the same
                      property obtained at room temperature. Thus, it appears that
                      SrTi$_{0.75}$Fe$_{0.25}$O$_{3-\delta}$ possesses an
                      anelastic behavior that might be associated with oxygen
                      release and/or primary creep deformation. In addition,
                      porous SrTi$_{0.75}$Fe$_{0.25}$O$_{3-\delta}$ specimens,
                      representative for use as porous substrate for supported
                      asymmetric oxygen transport membranes, were produced through
                      tape casting, freeze drying, and phase inversion casting.
                      The first method yielded a random distributed porosity with
                      spherical pores reaching a value of 32\%. Freeze-drying and
                      phase inversion, however, derived a channel-like porosity in
                      the same level. Ring-on-ring bending tests were employed in
                      order to derive elasticity and fracture stresses of the
                      manufactured samples. In order [...]},
      cin          = {IEK-2},
      cid          = {I:(DE-Juel1)IEK-2-20101013},
      pnm          = {111 - Efficient and Flexible Power Plants (POF3-111)},
      pid          = {G:(DE-HGF)POF3-111},
      typ          = {PUB:(DE-HGF)3 / PUB:(DE-HGF)11},
      urn          = {urn:nbn:de:0001-2019030710},
      url          = {https://juser.fz-juelich.de/record/857740},
}