Giant electrocaloric effect in high-energy electron irradiated P(VDF-TrFE) copolymers

S. G. Lu, X. Y. Li, J. P. Cheng, L. Gorny, Q. M. Zhang

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

A direct calorimetry method was developed and used to measure the electrocaloric effect (ECE). A temperature change ΔT of over 20°C and an entropy change ΔS of over 95 J/(kgK) were procured at 33°C and 160 MV/m in the high-energy electron irradiated poly(vinylidene fluoride- trifluoroethylene) (P(VDF-TrFE)) 68/32 mol% copolymers, which were larger than those of terpolymer blends (ΔT = 9°C, ΔS=46 J/(kgK) at 180 MV/m and room temperature) and our earlier report on P(VDF-TrFE) 55/45 mol% normal ferroelectric copolymer (12°C and 55 J/(kgK) at 80°C). We observed that the β value ((8.7±0.6)×10 7 JmC -2K -1) in the equation of ΔS=1/2βΔD 2 derived from ΔS - ΔD 2 relation for irradiated copolymers was larger than that of the terpolymer blends ((5.4±0.5)×10 7 JmC -2K -1). It was also found that the irradiated copolymer showed a sharp depolarization peak at T d < T m (maximum permittivity temperature), which is frequency independent, in the dielectric constant - temperature characteristics, a larger depolarization value at T d in the thermally stimulated depolarization current (TSDC) - temperature relationship, and a larger volume strain/longitudinal strain ratio over terpolymer blends. The giant ECE in irradiated copolymer is regarded as due to the greater randomness present in the relaxor state. In irradiated copolymers, the long all-trans chains are broken by the high-energy electrons, which make the small sized all-trans sequences more easily reorient along the electric field, more remarkably affecting the permittivity, TSDC, and volume strain.

Original languageEnglish (US)
Title of host publicationMagneto Calorics and Magnetic Cooling
Pages72-77
Number of pages6
DOIs
StatePublished - Dec 1 2011
Event2010 MRS Fall Meeting - Boston, MA, United States
Duration: Nov 29 2010Dec 3 2010

Publication series

NameMaterials Research Society Symposium Proceedings
Volume1310
ISSN (Print)0272-9172

Other

Other2010 MRS Fall Meeting
CountryUnited States
CityBoston, MA
Period11/29/1012/3/10

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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