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@MASTERSTHESIS{Zhou:1042345,
      author       = {Zhou, Wenling},
      title        = {{S}pin-{C}rossover in [{F}e({NQ}u3)({NCS})2]: {S}tructural
                      and {M}agnetic {S}tudies},
      school       = {RWTH Aachen University},
      type         = {Masterarbeit},
      address      = {Jülich},
      reportid     = {FZJ-2025-02540},
      pages        = {51 p.},
      year         = {2025},
      note         = {Masterarbeit, RWTH Aachen University, 2025},
      abstract     = {This thesis investigates the magnetic and structural
                      properties of two batches of single crystals (freshly
                      synthesized and aged) and polycrystalline material of the
                      spin-crossover (SCO) compound [Fe(NQu3)(NCS)2]∙0.5 Et2O
                      (Qu = quinoline and Et = ethyl). Magnetization measurements,
                      carried out on in-house Superconducting Quantum Interference
                      Device (SQUID) and on freshly synthesized single crystals,
                      indicate that the compound exhibits abrupt SCO behaviour
                      with a hysteresis width of 24.47 K. However, on freshly
                      synthesized polycrystalline samples and on aged single
                      crystals, only a paramagnetic signal was obtained across the
                      entire temperature range (20-300 K) (measured on the Quantum
                      Design Dynacool-PPMS (Physical Property Measurement
                      System)), indicating the absence of a SCO. Based on these
                      observations we believe that the particle size and the
                      solvent molecules play a critical role in governing the SCO
                      process.The compound crystallizes in the symmetry C2/c
                      (measured on in-house SuperNova single-crystal
                      diffractometer), with the lattice parameters and volume at
                      room temperature as a = 9.9054(2) Å, b = 22.3828(7) Å, c =
                      25.8754(8) Å, β = 95.5840(20)°, and V = 5709.63(45) Å3.
                      For both batches of single crystals, the symmetry was found
                      to remain unchanged across the entire investigated
                      temperature range (95-300 K). Based on the electron density
                      map, the potential positions of the solvent molecules in
                      freshly synthesized single crystals were identified.
                      However, the electron density of solvent molecules at the
                      same positions disappeared in aged single crystals.The fresh
                      samples show a SCO transition temperature (T1/2) at 138 K in
                      the cooling process and a temperature of 162.5 K in the
                      warming process. The lattice parameters a and c, along with
                      the angle β shrink significantly from HS to LS state, while
                      the lattice parameter b expands. The FeN6 octahedron
                      contracts non-uniformly from HS to LS state, in which the
                      Fe-N bonds are shortened by approximately 0.12 Å to 0.32
                      Å. Additionally, we observed a gradual increase in
                      mosaicity when cooling down the crystal.The results on the
                      fresh crystals are compared and contrasted with the single
                      crystal diffraction data of the “aged” single crystals,
                      which do not exhibit a SCO transition, but instead show a
                      smooth contraction of the unit cell volume with decreasing
                      temperature. The compound [Fe(NQu3)(NCS)2]∙0.5 Et2O is an
                      example of a spin crossover compound where the occurrence of
                      the transition seems to be entirely governed by the
                      concentration of solvent molecules. This serves as an
                      excellent entry point for understanding and investigating
                      the solvent-driven SCO phenomenon.},
      cin          = {JCNS-2 / JARA-FIT},
      cid          = {I:(DE-Juel1)JCNS-2-20110106 / $I:(DE-82)080009_20140620$},
      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)19},
      doi          = {10.34734/FZJ-2025-02540},
      url          = {https://juser.fz-juelich.de/record/1042345},
}