Achieving Ultrahigh Electrocaloric Response in (Bi<sub>0.5</sub>Na<sub>0.5</sub>)TiO<sub>3</sub>-Based Ceramics through B-Site Defect Engineering.
basic_science · Level V
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- Record sourced from PubMed, PMID 38728221.
- Also identified by DOI 10.1021/acsnano.4c03127.
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Abstract
Lead-free electrocaloric (EC) ferroelectrics are considered ideal for the next generation of environmentally friendly solid-state refrigeration materials. However, their inferior performance compared to lead-based materials significantly restricts their potential application. According to phase-field simulations, it is predicted that the pinning effect of a moderate number of defects can effectively enhance the reversible polarization response associated with the entropy change. Herein, sodium-bismuth titanate (BNT) ceramics with high spontaneous polarization are selected to construct B-site defects by introducing Li<sup>+</sup> and Nb<sup>5+</sup>. Under an electric field of 6 kV mm<sup>-1</sup>, ultrahigh EC temperature changes of Δ<i>T</i><sub>pos</sub> = 1.77 and Δ<i>T</i><sub>neg</sub> = 1.49 K are achieved at 65 °C by direct measurement (Δ<i>T</i><sub>neg</sub> > 1 K over 55-120 °C). Furthermore, Δ<i>T</i><sub>neg</sub> remains above 0.70 K in the temperature range from 25 to 130 °C, exhibiting immense potential for practical applications. This study offers a promising direction for optimizing the EC response in defect systems.