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Synergistically optimizing electrocaloric effect and temperature span in KNN-based ceramics utilizing relaxor multiphase boundary

Abstract

A combination of large adiabatic temperature change (∆T) and wide temperature span (Tspan) in lead-free ceramics is highly desired to develop eco-friendly and high-efficient solid-state refrigeration based on electrocaloric effect. However, the unsuccess in synergistically optimizing both large ∆T and wide Tspan in one material impedes practical applications of electrocaloric refrigeration technology. Here, a relaxor multiphase boundary (RMPB) is structured in (1-x)(K0.49Na0.49Li0.02)(Nb0.8Ta0.2)O3–xCaZrO3 (KNLNT–xCZ) ceramics through intentional composition engineering, successfully achieving a region of multiphase coexistence accompanied by diffuse phase transition. A moderate ∆T (0.63 K under 80 kV cm–1) with wide Tspan (43 K within 90% ∆T attenuation) is obtained in relaxor KNLNT–5CZ ceramic with coexistence of R-O-T phase. Results indicate that a coupling effect original from multi-directional polarization and polar nano-regions (PNRs) in RMPB contributes to the excellent performance combining large ∆T and wide Tspan. This work not only expands the applications of KNN-based ceramics from electric energy storage and piezoelectric applications to refrigeration field, but also opens up a new design avenue for the development of high performance electrocaloric materials with broad temperature ranges.

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Article information


Submitted
25 Nov 2019
Accepted
28 Jan 2020
First published
30 Jan 2020

J. Mater. Chem. C, 2020, Accepted Manuscript
Article type
Paper

Synergistically optimizing electrocaloric effect and temperature span in KNN-based ceramics utilizing relaxor multiphase boundary

J. Yang, Y. Zhao, X. Lou, J. Wu and X. Hao, J. Mater. Chem. C, 2020, Accepted Manuscript , DOI: 10.1039/C9TC06443E

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