Regensburg 2022 – wissenschaftliches Programm

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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 19: Ferroics – Domains and Domain Walls 2

KFM 19.2: Vortrag

Mittwoch, 7. September 2022, 15:20–15:40, H7

Dynamics of the electrocaloric effect in ferroelectric materials — •Jan Fischer, Daniel Hägele, and Jörg Rudolph — Ruhr-Universität Bochum, Faculty of Physics and Astronomy, Experimental Physics VI (AG), Germany

The electrocaloric effect (ECE) in ferroelectrics is a promising candidate for energy efficient cooling technologies. The ECE leads to a reversible adiabatic temperature change Δ T of a ferroelectric material upon a change of an external electric field. The reliable determination of the adiabatic Δ T is, however, experimentally challenging and most studies use either indirect methods which are prone to artifacts, or comparably slow direct methods. The dynamics of the ECE has therefore not been systematically studied so far. Here, we introduce a direct and contactless method to study the full dynamics Δ T(t) of the ECE with µK temperature resolution and µs temporal resolution via the infrared emission of the sample. The simultaneous recording of transients for Δ T(t), applied electric field E(t), and induced polarization P(t) gives the opportunity to correlate the caloric properties with the dielectric properties thus opening perspectives for a fundamental understanding of the ECE also in complex materials like relaxor ferroelectrics. Our techniques allows also for high-frequency measurements as needed for adiabatic measurements in thin films.1,2 We will discuss several examples ranging from bulk materials to thin films.
1 J., Döntgen, et al., Applied Physics Letters 106, 3 (2015)
2 J., Döntgen, et al., Energy Technology 6, 8 (2018)

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