Giant Barocaloric Effect at the Spin Crossover Transition of a Molecular Crystal

Steven P. Vallone, Anthony N. Tantillo, António M. dos Santos, Jamie J. Molaison, Rafal Kulmaczewski, Antonin Chapoy, Pezhman Ahmadi, Malcolm A. Halcrow, Karl G. Sandeman

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84 Scopus citations

Abstract

The first experimental evidence for a giant, conventional barocaloric effect (BCE) associated with a pressure-driven spin crossover transition near room temperature is provided. Magnetometry, neutron scattering, and calorimetry are used to explore the pressure dependence of the SCO phase transition in polycrystalline samples of protonated and partially deuterated [FeL2][BF4]2 [L = 2,6-di(pyrazol-1-yl)pyridine] at applied pressures of up to 120 MPa (1200 bar). The data indicate that, for a pressure change of only 0–300 bar (0–30 MPa), an adiabatic temperature change of 3 K is observed at 262 K or 257 K in the protonated and deuterated materials, respectively. This BCE is equivalent to the magnetocaloric effect (MCE) observed in gadolinium in a magnetic field change of 0–1 Tesla. The work confirms recent predictions that giant, conventional BCEs will be found in a wide range of SCO compounds.

Original languageEnglish
Article number1807334
JournalAdvanced Materials
Volume31
Issue number23
DOIs
StatePublished - Jun 6 2019

Funding

The authors are grateful to L. Mañosa and A.M. Pereira for useful discussions. S.P.V., A.N.T., and K.G.S. acknowledge that support for this project was provided by a PSC-CUNY Award, jointly funded by The Professional Staff Congress and The City University of New York. R.K. and M.A.H. thank Prof. John Blacker and Dr. Will Reynolds (Institute of Process Research and Development, University of Leeds) for access The authors are grateful to L. Ma?osa and A.M. Pereira for useful discussions. S.P.V., A.N.T., and K.G.S. acknowledge that support for this project was provided by a PSC-CUNY Award, jointly funded by The Professional Staff Congress and The City University of New York. R.K. and M.A.H. thank Prof. John Blacker and Dr. Will Reynolds (Institute of Process Research and Development, University of Leeds) for access to the autoclave reactor, and the EPSRC for funding (EP/K012568/1). A portion of this research used resources at the Spallation Neutron Source, and the Center for Nanophase Materials Science, both DOE Office of Science User Facilities operated by the Oak Ridge National Laboratory. to the autoclave reactor, and the EPSRC for funding (EP/K012568/1). A portion of this research used resources at the Spallation Neutron Source, and the Center for Nanophase Materials Science, both DOE Office of Science User Facilities operated by the Oak Ridge National Laboratory.

FundersFunder number
Center for Nanophase Materials Science
DOE Office of Science
PSC-CUNY
Research and Development
Oak Ridge National Laboratory
City University of New York
Engineering and Physical Sciences Research CouncilEP/K012568/1
University of Leeds

    Keywords

    • barocaloric effect
    • deuteration
    • solid-state cooling
    • spin crossover

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