A scaling law for distinct electrocaloric cooling performance in low-dimensional organic, relaxor and anti-ferroelectrics

Shi, Yuping and Huang, Limin and Soh, Ai Kah and Weng, George J. and Liu, Shuangyi and Redfern, Simon A. T. (2017) A scaling law for distinct electrocaloric cooling performance in low-dimensional organic, relaxor and anti-ferroelectrics. Scientific Reports, 7 (1). ISSN 2045-2322 DOI https://doi.org/10.1038/s41598-017-11633-y

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Official URL: http://doi.org/10.1038/s41598-017-11633-y

Abstract

Electrocaloric (EC) materials show promise in eco-friendly solid-state refrigeration and integrable on-chip thermal management. While direct measurement of EC thin-films still remains challenging, a generic theoretical framework for quantifying the cooling properties of rich EC materials including normal-, relaxor-, organic- and anti-ferroelectrics is imperative for exploiting new flexible and room-temperature cooling alternatives. Here, we present a versatile theory that combines Master equation with Maxwell relations and analytically relates the macroscopic cooling responses in EC materials with the intrinsic diffuseness of phase transitions and correlation characteristics. Under increased electric fields, both EC entropy and adiabatic temperature changes increase quadratically initially, followed by further linear growth and eventual gradual saturation. The upper bound of entropy change (∆Smax) is limited by distinct correlation volumes (V cr ) and transition diffuseness. The linearity between V cr and the transition diffuseness is emphasized, while ∆Smax = 300 kJ/(K.m3) is obtained for Pb0.8Ba0.2ZrO3. The ∆Smax in antiferroelectric Pb0.95Zr0.05TiO3, Pb0.8Ba0.2ZrO3 and polymeric ferroelectrics scales proportionally with V cr −2.2, owing to the one-dimensional structural constraint on lattice-scale depolarization dynamics; whereas ∆Smax in relaxor and normal ferroelectrics scales as ∆Smax ~ V cr −0.37, which tallies with a dipolar interaction exponent of 2/3 in EC materials and the well-proven fractional dimensionality of 2.5 for ferroelectric domain walls.

Item Type: Article
Uncontrolled Keywords: 2017AREP; IA73;
Subjects: 03 - Mineral Sciences
Divisions: 03 - Mineral Sciences
07 - Gold Open Access
Journal or Publication Title: Scientific Reports
Volume: 7
Identification Number: https://doi.org/10.1038/s41598-017-11633-y
Depositing User: Sarah Humbert
Date Deposited: 15 Sep 2017 11:22
Last Modified: 01 Oct 2017 19:43
URI: http://eprints.esc.cam.ac.uk/id/eprint/4053

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