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@INPROCEEDINGS{Bram:1008356,
      author       = {Bram, Martin and Mishra, Tarini Prasad and Wang, Shufan and
                      Lenser, Christian and Jennings, Dylan and Kindelmann, Moritz
                      and Rheinheimer, Wolfgang and Broeckmann, Christoph and
                      Guillon, Olivier},
      title        = {{U}ltra-fast high temperature sintering ({UHS}) of
                      strontium titanate},
      reportid     = {FZJ-2023-02302},
      year         = {2023},
      abstract     = {Recently, ultra-fast high-temperature sintering (UHS) has
                      been introduced as novel fast sintering method. UHS enables
                      rapid densification of ceramic materials within seconds [1].
                      Therefore, green compacts are placed between thin strips of
                      carbon felt, which are then heated by direct current. Joule
                      heating of the stripes enables extremely high heating rates
                      beyond 104 K/min. In the present work, strontium titanate
                      and 2 mol. $\%$ iron doped strontium titanate were used as
                      model materials for systematically studying the relationship
                      between UHS parameters and resulting properties [2]. Similar
                      to other fast sintering technologies, exact control and
                      measurement of temperature and the occurrence of larger
                      temperature gradients remain challenging. Therefore, FEM
                      modelling was conducted to estimate the temperature
                      distribution of setup and sample. FEM model was validated by
                      thermocouple, pyrometer and melt phase formation at
                      predicted temperatures. Figure 1 exemplarily shows the
                      temperature distribution of the used setup (carbon stripe 80
                      x 10 x 4 mm heated by DC current varying between 5 and 24
                      A). A special focus was to investigate the influence of the
                      applied current on degree of densification and resulting
                      grain size. For both materials, rapid densification of small
                      samples (diameter 8 mm, height 1 mm) within 10 s was
                      demonstrated successfully. In the case of undoped strontium
                      titanate, exaggerated grain growth in combination with the
                      formation of isolated pores was observed. The addition of 2
                      mol. $\%$ iron helped to limit the grain growth and
                      therefore enabled a more uniform densification and grain
                      growth. On the other hand, these samples were more
                      susceptible to cracking, especially at higher currents.
                      Segregation of cations at grain boundaries was analysed by
                      scanning transmission electron microscopy/energy disperse
                      x-ray spectroscopy (STEM/EDS). Electrical performance of
                      both materials was demonstrated by impedance spectroscopy. A
                      comparison of the conductivity of UHS sintered and
                      conventionally sintered samples did not show remarkable
                      differences.},
      month         = {Mar},
      date          = {2023-03-19},
      organization  = {Electric field enhanced processing of
                       advanced materials III: Complexities
                       and opportunities, Tomar (Portugal), 19
                       Mar 2023 - 24 Mar 2023},
      subtyp        = {Other},
      cin          = {IEK-1},
      cid          = {I:(DE-Juel1)IEK-1-20101013},
      pnm          = {899 - ohne Topic (POF4-899)},
      pid          = {G:(DE-HGF)POF4-899},
      typ          = {PUB:(DE-HGF)6},
      url          = {https://juser.fz-juelich.de/record/1008356},
}