The electrocaloric effect (ECE) in ferroelectric polymer films

Lu, Sheng Guo; Zhang, Q.M.; Kutnjak, Zdravko

doi:10.1533/9780857093295.2.364

Cited by 4 publications

(6 citation statements)

References 39 publications

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“…On the other hand, Fig.2(a)clearly reveals that the EC coefficient of the MD method significantly differs from that predicted by MC-1 and MC-2 at 100 K, as a result of non-ergodicity. In particular, at 100 K, the α deduced from the indirect methods are smaller than that those directly extracted, which is in agreement with previous reports[25,53,55]. It is also interesting to realize that the EC coefficient of the MD method gets closer to those of MC-1 and MC-2 at 100 K for the highest considered electric fields.…”

supporting

confidence: 90%

“…Note that data from MC-1 and MC-2 approaches can be considered to be associated with the indirect method to obtain EC effects, because they are based on thermodynamic equilibrium. On the other hand, data obtained from MD computations yield the direct EC effects, which may differ from those obtained from the indirect way for systems adopting non-ergodic behavior, as the one that relaxors are known to exhibit below some specific temperature T m at which the dielectric response peaks [53]. Comparisons between our MC and MD results should thus tell us the difference between the indirect and direct ways to extract EC effects in relaxors.…”

Section: Methodsmentioning

confidence: 69%

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Electrocaloric effects in the lead-free Ba(Zr,Ti)O3 relaxor ferroelectric from atomistic simulations

et al. 2017

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Atomistic effective Hamiltonian simulations are used to investigate electrocaloric (EC) effects in the lead-free Ba(Zr0.5Ti0.5)O3 (BZT) relaxor ferroelectric. We find that the EC coefficient varies non-monotonically with the field at any temperature, presenting a maximum that can be traced back to the behavior of BZT's polar nanoregions. We also introduce a simple Landau-based model that reproduces the EC behavior of BZT as a function of field and temperature, and which is directly applicable to other compounds. Finally, we confirm that, for low temperatures (i.e., in non-ergodic conditions), the usual indirect approach to measure the EC response provides an estimate that differs quantitatively from a direct evaluation of the field-induced temperature change.

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supporting

confidence: 90%

Section: Methodsmentioning

confidence: 69%

Electrocaloric effects in the lead-free Ba(Zr,Ti)O3 relaxor ferroelectric from atomistic simulations

et al. 2017

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“…It is known that the permittivity of VDF-TrFE copolymer is strongly influenced by a DC bias field. At the Curie transition temperature and beyond the permittivity of 55/45 copolymer is reduced by more than 30 % under the influence of a DC bias field of 10 V/m [7].…”

Section: Resultsmentioning

confidence: 99%

“…It is known that the ferroelectric to paraelectric transition of a ferroelectric material is shifted to higher temperatures or even completely hindered under the influence of a DC bias field. Moderate fields of 10 MV/m keep a 55/45 VDF-TrFE copolymer polar up to temperatures of more than 140 °C [7]. The electric fields in a copolymer bilayer caused by the absence of sufficient free charge at the dielectric-dielectric interface influencing the permittivity will also modify the polarisation versus temperature relation.…”

Section: Resultsmentioning

confidence: 99%

Ferroelectric properties of polymeric bilayer systems

Nordheim

Austin

Ploss

et al. 2016

IEEE Trans. Dielect. Electr. Insul.

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Bilayers of VDF-TrFE ferroelectric copolymer thin films have been characterised in terms of polarisation behaviour and dielectric nonlinearities. The effective properties of the ferroelectric bilayers have been investigated and compared with those of the individual layers in the stack. It has been demonstrated that the effective permittivity of the bilayer is not fully described by a simple series model. The remanent polarisation P r in the bilayer shows essentially a linear decrease with temperature and reaches zero at around 120 °C, i.e. above the Curie temperatures of the two copolymers involved. The two observations are attributed to electric bias fields in the bilayer which cause a coupling between the two layers and lead to a temperature dependence of the polarisation which is phenomenologically similar to observations in superlattices.

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“…Nowadays, ECE attracts scientists’ attention because of its promising frigorific applications and microelectronic cooling devices [ 8 , 9 , 10 ]. Various contributions were recently reported on ferroelectric thin films, ceramic and polymers [ 1 , 7 , 11 , 12 ].…”

Section: Introductionmentioning

confidence: 99%

Large Electrocaloric Responsivity and Energy Storage Response in the Lead-Free Ba(GexTi1−x)O3 Ceramics

et al. 2022

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Ferroelectric property that induces electrocaloric effect was investigated in Ba(GexTi1−x)O3 ceramics, known as BTGx. X-ray diffraction analysis shows pure perovskite phases in tetragonal symmetry compatible with the P4mm (No. 99) space group. Dielectric permittivity exhibits first-order ferroelectric-paraelectric phase transition, confirmed by specific heat measurements, similar to that observed in BaTiO3 (BTO) crystal. Curie temperature varies weakly as a function of Ge-content. Using the direct and indirect method, we confirmed that the adiabatic temperature change ΔT reached its higher value of 0.9 K under 8 kV/cm for the composition BTG6, corresponding to an electrocaloric responsivity ΔT/ΔE of 1.13 × 10−6 K.m/V. Such electrocaloric responsivity significantly exceeds those obtained so far in other barium titanate-based lead-free electrocaloric ceramic materials. Energy storage investigations show promising results: stored energy density of ~17 mJ/cm3 and an energy efficiency of ~88% in the composition BTG5. These results classify the studied materials as candidates for cooling devices and energy storage applications.

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The electrocaloric effect (ECE) in ferroelectric polymer films

Cited by 4 publications

References 39 publications

Electrocaloric effects in the lead-free Ba(Zr,Ti)O3 relaxor ferroelectric from atomistic simulations

Electrocaloric effects in the lead-free Ba(Zr,Ti)O3 relaxor ferroelectric from atomistic simulations

Ferroelectric properties of polymeric bilayer systems

Large Electrocaloric Responsivity and Energy Storage Response in the Lead-Free Ba(GexTi1−x)O3 Ceramics

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