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Measuring Magnetically-Tuned Ferroelectric Polarization in Liquid Crystals
Published on: August 15, 2018
Large electrocaloric effect in ferroelectric polymers near room temperature.
Bret Neese1, Baojin Chu, Sheng-Guo Lu
1Materials Research Institute, Pennsylvania State University, University Park, PA 16802, USA.
Science (New York, N.Y.)
|August 9, 2008
Summary
Researchers explored the electrocaloric effect (ECE) in polar polymers for cooling. They found significant ECE in P(VDF-TrFE) and related polymers, demonstrating potential for advanced solid-state cooling technologies.
Area of Science:
- Materials Science
- Thermodynamics
- Polymer Science
Background:
- Applying electrical fields to polar polymers can alter dipolar ordering, potentially enabling cooling applications via entropy changes.
- The electrocaloric effect (ECE) is a promising phenomenon for solid-state cooling, driven by changes in a material's entropy under an electric field.
Purpose of the Study:
- To investigate the electrocaloric effect in ferroelectric polymers, specifically P(VDF-TrFE) and related copolymers.
- To quantify the isothermal entropy change and adiabatic temperature change achievable with these materials for cooling applications.
Main Methods:
- Utilized the Maxwell relation connecting the pyroelectric coefficient and the electrocaloric effect.
- Experimentally measured ECE in ferroelectric poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] copolymer.
- Investigated a relaxor ferroelectric polymer, P(VDF-TrFE-chlorofluoroethylene), for ECE near room temperature.
Main Results:
- Achieved a large electrocaloric effect in P(VDF-TrFE) above 70°C (above the ferroelectric-paraelectric transition).
- Observed an isothermal entropy change exceeding 55 J/kg·K and an adiabatic temperature change over 12°C.
- Demonstrated comparable ECE near room temperature in P(VDF-TrFE-chlorofluoroethylene).
Conclusions:
- Ferroelectric polymers like P(VDF-TrFE) exhibit significant electrocaloric effects suitable for cooling.
- Relaxor ferroelectric polymers offer potential for room-temperature solid-state cooling applications.
- The study highlights the viability of polymer-based electrocaloric materials for efficient thermal management.
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