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Large electrocaloric effects in oxide multilayer capacitors over a wide temperature range.
B Nair1, T Usui2, S Crossley1
1Department of Materials Science, University of Cambridge, Cambridge, UK.
Nature
|October 10, 2019
Summary
New electrocaloric materials offer significant temperature changes for advanced heat pumps. High-quality multilayer capacitors achieve 5.5 K temperature shifts near room temperature, improving upon existing magnetocaloric and electrocaloric technologies.
Area of Science:
- Solid-state physics
- Materials science
- Thermodynamics
Background:
- Heat pumps utilize magnetocaloric and electrocaloric effects for cooling, driven by magnetic and electric fields, respectively.
- Current prototypes are limited by small temperature changes (< 3 K) in working bodies, hindering practical performance.
- Existing technologies rely on permanent magnets or high voltages, posing cost and bulk challenges.
Purpose of the Study:
- To demonstrate a novel electrocaloric material for enhanced heat pump performance.
- To investigate the electrocaloric effect in multilayer capacitors of PbSc0.5Ta0.5O3.
- To explore the potential of repurposing heat pump designs with advanced electrocaloric materials.
Main Methods:
- Fabrication of high-quality multilayer capacitors using PbSc0.5Ta0.5O3.
- Application of supercritical electric fields (29.0 V/µm) above the Curie temperature (290 K) to drive ferroelectric phase transitions.
- Verification of phase transition behavior using Landau theory.
- Measurement of temperature changes across the capacitor's central area.
Main Results:
- PbSc0.5Ta0.5O3 capacitors exhibit large electrocaloric effects over a wide temperature range.
- Peak temperature changes reach 5.5 K near room temperature.
- Temperature changes exceeding 3 K are observed across a 176 K span.
- Supercritical driving of the first-order ferroelectric phase transition is confirmed.
Conclusions:
- High-quality multilayer capacitors of PbSc0.5Ta0.5O3 demonstrate significant electrocaloric effects.
- These materials offer a promising alternative to current magnetocaloric and electrocaloric working bodies.
- Repurposing existing magnetocaloric heat pump designs with these capacitors could lead to improved performance without bulky magnets.
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