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Coexistence of giant positive and large negative electrocaloric effects in lead-free ferroelectric thin film for continuous solid-state refrigeration

Journal Article


Abstract


  • The solid-state cooling technique utilizing electrocaloric (EC) materials is an alternative approach to tackle the greenhouse effect caused by traditional vapor-compression refrigeration. However, such a promising technique is severely hampered by the lack of proper materials considering that most existing EC materials with a single positive/negative EC effect exhibit a limited cooling effect. Here, the coexistence of a positive and negative EC effects has been achieved in a lead-free Na0.5Bi0.5(Ti0.97W0.01Fe0.02)O3 ferroelectric film. A state-of-the-art positive adiabatic temperature change (ΔT) of ~56 K accompanied by an isothermal entropy change (ΔS) of ~64 J K−1 kg−1 at 143 °C and a large negative ΔT of ~ − 17 K with a ΔS of ~ − 24 J K−1 kg−1 at 55 °C are obtained under a strong electric field strength of 2692 kV cm−1. Oxygen vacancy-related defect dipoles play a critical role in the negative EC effect at lower temperatures, while the phase transition is responsible for the positive EC effect at higher temperatures. Meanwhile, the film exhibits a high EC strength with a maximum ΔT/ΔE of 0.021 K cm kV−1, together with a ΔS/ΔE of 0.024 J cm K−1 kg−1 kV−1. This work ensures a giant total temperature change by utilizing and combining both the negative and positive EC effects in a dual cooling process.

Publication Date


  • 2021

Citation


  • Yang, C., Feng, C., Lv, P., Qian, J., Han, Y., Lin, X., . . . Cheng, Z. (2021). Coexistence of giant positive and large negative electrocaloric effects in lead-free ferroelectric thin film for continuous solid-state refrigeration. Nano Energy, 88. doi:10.1016/j.nanoen.2021.106222

Scopus Eid


  • 2-s2.0-85107774048

Web Of Science Accession Number


Volume


  • 88

Abstract


  • The solid-state cooling technique utilizing electrocaloric (EC) materials is an alternative approach to tackle the greenhouse effect caused by traditional vapor-compression refrigeration. However, such a promising technique is severely hampered by the lack of proper materials considering that most existing EC materials with a single positive/negative EC effect exhibit a limited cooling effect. Here, the coexistence of a positive and negative EC effects has been achieved in a lead-free Na0.5Bi0.5(Ti0.97W0.01Fe0.02)O3 ferroelectric film. A state-of-the-art positive adiabatic temperature change (ΔT) of ~56 K accompanied by an isothermal entropy change (ΔS) of ~64 J K−1 kg−1 at 143 °C and a large negative ΔT of ~ − 17 K with a ΔS of ~ − 24 J K−1 kg−1 at 55 °C are obtained under a strong electric field strength of 2692 kV cm−1. Oxygen vacancy-related defect dipoles play a critical role in the negative EC effect at lower temperatures, while the phase transition is responsible for the positive EC effect at higher temperatures. Meanwhile, the film exhibits a high EC strength with a maximum ΔT/ΔE of 0.021 K cm kV−1, together with a ΔS/ΔE of 0.024 J cm K−1 kg−1 kV−1. This work ensures a giant total temperature change by utilizing and combining both the negative and positive EC effects in a dual cooling process.

Publication Date


  • 2021

Citation


  • Yang, C., Feng, C., Lv, P., Qian, J., Han, Y., Lin, X., . . . Cheng, Z. (2021). Coexistence of giant positive and large negative electrocaloric effects in lead-free ferroelectric thin film for continuous solid-state refrigeration. Nano Energy, 88. doi:10.1016/j.nanoen.2021.106222

Scopus Eid


  • 2-s2.0-85107774048

Web Of Science Accession Number


Volume


  • 88