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@INPROCEEDINGS{Qi:1043681,
      author       = {Qi, J. and Prakash, P. and Schwärzer, K. and Shahed, H.
                      and Allgaier, Jürgen and Perßon, J. and Sergeev, I. and
                      Glazyrin, K. and Rols, S. and De Souza, N. and Yu, D. and
                      Grzechnik, A. and Angst, M. and Voigt, J. and Friese, K. and
                      Sohn, Y. and Prajapat, D.},
      title        = {{E}lucidating entropy contributions of barocaloric effect
                      in spin crossover complex {F}e({PM}-{B}i{A})2({NCS})2},
      reportid     = {FZJ-2025-02979},
      year         = {2025},
      abstract     = {Background: The barocaloric effect (BCE) is characterized
                      as a thermal response in solid-state materials induced by
                      external hydrostatic pressure. Cooling technologies based on
                      the BCE have emerged as a promising alternative to
                      conventional vapor-compression cooling. Recently, spin
                      crossover (SCO) transitions, where the low spin and high
                      spin states can be switched by hydrostatic pressure, were
                      proposed as a potential mechanism to generate outstanding
                      BCE. Fe(PM-BiA)2(NCS)2 (with PM = N-2’- pyridylmethylene
                      and BiA = 4-aminobiphenyl) is a classic SCO complex that
                      crystalizes in two different structures, orthorhombic with
                      abrupt transition and monoclinic with gradual transition. In
                      this work, we aim to unveil the entropy contributions of
                      Fe(PM-BiA)2(NCS)2 for optimizing the BCE performance on SCO
                      complexes. Methods: Spectroscopic methods including nuclear
                      inelastic scattering (NIS, P01), inelastic neutron
                      scattering (INS, PANTHER $\&$ PELICAN) and quasi elastic
                      scattering (QENS, PANTHER $\&$ EMU) have been used for
                      dynamic studies of Fe(PM-BiA)2(NCS)2. Results: The dynamic
                      features of both polymorphs over a large energy range are
                      highlighted by spectroscopic methods. The complete and
                      Fe-related lattice dynamics have been accessed through INS
                      and NIS, respectively. It indicates that the Fe-related
                      entropy change across the spin transition is around $54.6\%$
                      of the total entropy change. The single crystal X-ray
                      diffraction evidences the potential dynamic disorder of
                      phenyl groups. A two-site reorientation mode of the phenyl
                      group at the ps time scale has been observed by QENS. This
                      local mode also generates $12\%$ of the total entropy
                      change.Conclusion: In summary, we confirm that both the
                      phonon excitations of Fe-N octahedron and the local motions
                      of phenyl groups play crucial roles in contributing to the
                      total entropy change in Fe(PM-BiA)2(NCS)2. Our study will
                      enhance the understanding of the caloric effect in the SCO
                      complex and promote the application of SCO complexes as BCE
                      refrigerants.},
      month         = {Jul},
      date          = {2025-07-06},
      organization  = {The International Conference on
                       Neutron Scattering, Bella Center in
                       Copenhagen, Denmark, with the last day
                       at the European Spallation Source (ESS)
                       in nearby Lund, Sweden (Denmark), 6 Jul
                       2025 - 10 Jul 2025},
      subtyp        = {Invited},
      cin          = {JCNS-2 / JARA-FIT / JCNS-1 / JCNS-4},
      cid          = {I:(DE-Juel1)JCNS-2-20110106 / $I:(DE-82)080009_20140620$ /
                      I:(DE-Juel1)JCNS-1-20110106 / I:(DE-Juel1)JCNS-4-20201012},
      pnm          = {632 - Materials – Quantum, Complex and Functional
                      Materials (POF4-632) / 6G4 - Jülich Centre for Neutron
                      Research (JCNS) (FZJ) (POF4-6G4)},
      pid          = {G:(DE-HGF)POF4-632 / G:(DE-HGF)POF4-6G4},
      typ          = {PUB:(DE-HGF)24},
      url          = {https://juser.fz-juelich.de/record/1043681},
}