Extraordinarily Large Electrocaloric Strength of Metal-Free Perovskites.
basic_science · Level V
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- Record sourced from PubMed, PMID 31880026.
- Also identified by DOI 10.1002/adma.201906224.
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Abstract
The availability of materials with high electrocaloric (EC) strengths is critical to enabling EC refrigeration in practical applications. Although large EC entropy changes, ΔS<sub>EC</sub> , and temperature changes, ΔT<sub>EC</sub> , have been achieved in traditional thin-film ceramics and polymer ferroelectrics, they require the application of very high electric fields and thus their EC strengths ΔS<sub>EC</sub> /ΔE and ΔT<sub>EC</sub> /ΔE are too low for practical applications. Here, a fundamental thermodynamic description is developed, and extraordinarily large EC strengths of a metal-free perovskite ferroelectric [MDABCO](NH<sub>4</sub> )I<sub>3</sub> (MDABCO) are predicted. The predicted EC strengths: isothermal ΔS<sub>EC</sub> /ΔE and adiabatic ΔT<sub>EC</sub> /ΔE for MDABCO are 18 J m kg<sup>-1</sup> K<sup>-1</sup> MV<sup>-1</sup> and 8.06 K m MV<sup>-1</sup> , respectively, more than three times the largest reported values in BaTiO<sub>3</sub> single crystals. These predictions strongly suggest the metal-free ferroelectric family of materials as the best candidates among existing materials for EC applications. The present work not only presents a general approach to developing thermodynamic potential energy functions for ferroelectric materials but also suggests a family of candidate materials with potentially extremely high EC performance.