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Shahed H, Sharma N, Angst M, Voigt J, Perßon J, Prakash P, Törnroos KW, Chernyshov D, Gildenast H, Ohl M, Saffarini G, Grzechnik A, Friese K. Structural insight into the cooperativity of spin crossover compounds. Acta Crystallogr B Struct Sci Cryst Eng Mater 2023; 79:354-367. [PMID: 37578185 PMCID: PMC10552598 DOI: 10.1107/s2052520623005814] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Accepted: 07/02/2023] [Indexed: 08/15/2023]
Abstract
Spin-crossover (SCO) compounds are promising materials for a wide variety of industrial applications. However, the fundamental understanding of their nature of transition and its effect on the physical properties are still being fervently explored; the microscopic knowledge of their transition is essential for tailoring their properties. Here an attempt is made to correlate the changes in macroscopic physical properties with microscopic structural changes in the orthorhombic and monoclinic polymorphs of the SCO compound Fe(PM-Bia)2(NCS)2 (PM = N-2'-pyridylmethylene and Bia = 4-aminobiphenyl) by employing single-crystal X-ray diffraction, magnetization and DSC measurements. The dependence of macroscopic properties on cooperativity, highlighting the role of hydrogen bonding, π-π and van der Waals interactions is discussed. Values of entropy, enthalpy and cooperativity are calculated numerically based on the Slichter-Drickamer model. The particle size dependence of the magnetic properties is probed along with the thermal exchange and the kinetic behavior of the two polymorphs based on the dependence of magnetization on temperature scan rate and a theoretical model is proposed for the calculation of the non-equilibrium spin-phase fraction. Also a scan-rate-dependent two-step behavior observed for the orthorhombic polymorph, which is absent for the monoclinic polymorph, is reported. Moreover, it is found that the radiation dose from synchrotron radiation affects the spin-crossover process and shifts the transition region to lower temperatures, implying that the spin crossover can be tuned with radiation damage.
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Affiliation(s)
- H. Shahed
- Jülich Centre for Neutron Science (JCNS-2) and Peter Grünberg Institute (PGI-4), Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
- Institute of Crystallography, RWTH Aachen University, Jägerstr. 17-19, 52066 Aachen, Germany
| | - N. Sharma
- Jülich Centre for Neutron Science (JCNS-2) and Peter Grünberg Institute (PGI-4), Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
| | - M. Angst
- Jülich Centre for Neutron Science (JCNS-2) and Peter Grünberg Institute (PGI-4), Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
| | - J. Voigt
- Jülich Centre for Neutron Science (JCNS-2) and Peter Grünberg Institute (PGI-4), Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
| | - J. Perßon
- Jülich Centre for Neutron Science (JCNS-2) and Peter Grünberg Institute (PGI-4), Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
| | - P. Prakash
- Jülich Centre for Neutron Science (JCNS-2) and Peter Grünberg Institute (PGI-4), Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
| | - K. W. Törnroos
- Department of Chemistry, University of Bergen, Allégaten 41, N-5007 Bergen, Norway
| | - D. Chernyshov
- Swiss–Norwegian Beamlines at the European Synchrotron Radiation Facility, 38000 Grenoble, France
| | - H. Gildenast
- Institute of Inorganic Chemistry, RWTH Aachen University, 52074 Aachen, Germany
| | - M. Ohl
- Jülich Centre for Neutron Science (JCNS-1), Forschungszentrum Jülich, 52425 Jülich, Germany
- Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - G. Saffarini
- Physics Department, An-Najah National University, Nablus, Palestine
| | - A. Grzechnik
- Institute of Crystallography, RWTH Aachen University, Jägerstr. 17-19, 52066 Aachen, Germany
- Jülich Centre for Neutron Science (JCNS-4), Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
| | - K. Friese
- Jülich Centre for Neutron Science (JCNS-2) and Peter Grünberg Institute (PGI-4), Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
- Institute of Crystallography, RWTH Aachen University, Jägerstr. 17-19, 52066 Aachen, Germany
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Shahed H, Sharma N, Angst M, Voigt J, Persson J, Gildenast H, Englert U, Chernyshov D, Tornroos K, Grzechnik A, Friese K. Elucidation of barocaloric effect in spin crossover compounds. Acta Cryst Sect A 2022. [DOI: 10.1107/s2053273322092932] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/19/2023]
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Dey S, Nandi S, Gildenast H, Shahed H, Hakala V, Grzechnik A, Paulmann C, Tolkiehn M, Englert U, Roth G, Peters L. Phase transitions in flexible crystals of cocrystal solvate of caffeine. Acta Cryst Sect A 2022. [DOI: 10.1107/s2053273322092798] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/19/2023]
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