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Large Electrocaloric Effect in a Dielectric Liquid Possessing a Large Dielectric Anisotropy Near the Isotropic–Nematic Transition

Authors

  • Xiao-Shi Qian,

    1. Department of Electrical Engineering and Materials Research Institute, The Pennsylvania State University, University Park, PA 16802, USA
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  • Sheng-Guo Lu,

    1. Department of Electrical Engineering and Materials Research Institute, The Pennsylvania State University, University Park, PA 16802, USA
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  • Xinyu Li,

    1. Department of Electrical Engineering and Materials Research Institute, The Pennsylvania State University, University Park, PA 16802, USA
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  • Haiming Gu,

    1. Department of Electrical Engineering and Materials Research Institute, The Pennsylvania State University, University Park, PA 16802, USA
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  • Liang-Chy Chien,

    1. Liquid Crystal Institute and Department of Chemical Physics, Kent State University, Kent, OH 44242, USA
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  • Qiming Zhang

    Corresponding author
    1. Department of Electrical Engineering and Materials Research Institute, The Pennsylvania State University, University Park, PA 16802, USA
    • Department of Electrical Engineering and Materials Research Institute, The Pennsylvania State University, University Park, PA 16802, USA.
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Abstract

The recent findings of large electrocaloric effects (ECEs) in ferroelectric polymers and in ferroelectric ceramic thin films have attracted great interest for developing new cooling cycles that are environmental friendly and have the potential to reach better efficiency than the existing vapor-compression approach. Compared with these solid state ECE materials, a dielectric fluid with a large ECE can be more interesting because it may lead to new cooling cycles with simpler structures than these based on solid state ECE materials. Here it is shown that a large ECE can be realized in the liquid crystal (LC) 5CB near its nematic–isotropic (N-I) phase transition. 5CB has a large dielectric anisotropy, which facilitates the electric-field-induced large polarization change. As a result, a large ECE, i.e., an isothermal entropy change of more than 23.6 J kg−1 K−1 is observed just above the N-I transition.

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