The electrocaloric effect around the orthorhombic- tetragonal first-order phase transition in BaTiO3

Bai, Yang; Ding, Kai; Zheng, Guang; Shi, San-Qiang; Cao, Jiang; Li, Qiao

doi:10.1063/1.4732146

Cited by 61 publications

(15 citation statements)

References 21 publications

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“…In contrast to current regeneration-based EC devices that exploit EC-passive regeneration material, devices exploiting an LC EC-active regenerator could significantly improve cooling power/mass ratio. Note that the obtained EC responses in LCs are comparable to those measured in competitive solid dielectric materials 30–32 . However, introducing LCs as EC material might open the gates to several new EC-based applications.…”

Section: Discussionsupporting

confidence: 72%

Giant electrocaloric response in smectic liquid crystals with direct smectic-isotropic transition

Klemenčič

Trček

Kutnjak

et al. 2019

Sci Rep

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Electrocaloric materials have become a viable technology for solid state heat management applications. We demonstrate both theoretically and experimentally that liquid crystals (LCs) can be exploited as efficient electrocaloric materials. Numerical and experimental investigations determine the conditions under which the strongest electrocaloric effect (ECE) responses are expected in LCs. Specifically, we show that a large ECE can be expected at the isotropic-nematic and in particular at the isotropic-smectic A phase transition. In our theoretical study, LC ordering is modelled using a Landau – de Gennes - Ginzburg mesoscopic approach. The simulation results are in qualitative agreement with our high precision electrocaloric measurements conducted on 8CB and 12CB liquid crystals. In the latter, we obtained ΔTEC ~ 6.5 K, corresponding to the largest response measured so far in LCs. The fluid property of LC electrocaloric heat cooling elements could lead to the development of devices with a higher coefficient of performance and thus better cooling power yield per mass of the ECE-based device.

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Section: Discussionsupporting

confidence: 72%

Giant electrocaloric response in smectic liquid crystals with direct smectic-isotropic transition

Klemenčič

Trček

Kutnjak

et al. 2019

Sci Rep

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“…Indeed, an EC effect corresponding to a temperature change of 1.4 K under application of an electric field of 10 kV/cm has been reported at the T-O transition in BTO. 21 Furthermore, ab initio-based studies predict sizable EC temperature changes both at the T-O and at the O-R transition in BTO, 18 as well as in the closely related compound Ba 0.5 Sr 0.5 TiO 3 . 22 A finite EC response has also been measured at FE-FE transitions in other ferroelectrics, e.g., Pb(Mg 1/3 Nb 2/3 )O 3 -PbTiO 3 single crystals.…”

Section: Introductionmentioning

confidence: 99%

Electrocaloric effect in BaTiO3 at all three ferroelectric transitions: Anisotropy and inverse caloric effects

et al. 2017

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We study the electrocaloric (EC) effect in bulk BaTiO3 (BTO) using molecular dynamics simulations of a first principles-based effective Hamiltonian, combined with direct measurements of the adiabatic EC temperature change in BTO single crystals. We examine in particular the dependence of the EC effect on the direction of the applied electric field at all three ferroelectric transitions, and we show that the EC response is strongly anisotropic. Most strikingly, an inverse caloric effect, i.e., a temperature increase under field removal, can be observed at both ferroelectric-ferroelectric transitions for certain orientations of the applied field. Using the generalized Clausius-Clapeyron equation, we show that the inverse effect occurs exactly for those cases where the field orientation favors the higher temperature/higher entropy phase. Our simulations show that temperature changes of around 1 K can in principle be obtained at the tetragonal-orthorhombic transition close to room temperature, even for small applied fields, provided that the applied field is strong enough to drive the system across the first order transition line. Our direct EC measurements for BTO single crystals at the cubic-tetragonal and at the tetragonal-orthorhombic transitions are in good qualitative agreement with our theoretical predictions, and in particular confirm the occurrence of an inverse EC effect at the tetragonal-orthorhombic transition for electric fields applied along the [001] pseudo-cubic direction.

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“…The peak isothermal entropy change |∆S| ∼ 1.6 ± 0.2 J K −1 kg −1 near ∼400 K is achieved with a low value of |∆p| = 1 kbar [Figures 3(c) and 3(d)], yielding large BC strengths, 5 |∆S|/|∆p| and |Q|/|∆p| (Table I) kg −1 appears to be similar for ∆p = ±1 kbar, the peak occurs at different temperatures, evidencing inverse irreversible BC effects. This irreversibility, which is also seen for conventional EC effects near the T-O transition, 43 arises because of the relatively large thermal hysteresis. Therefore caloric effects near the T-O transition are unsuitable for continuous cooling, and so we do not present RC values.…”

mentioning

confidence: 98%

Inverse barocaloric effects in ferroelectric BaTiO3 ceramics

et al. 2016

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We use calorimetry to identify pressure-driven isothermal entropy changes in ceramic samples of the prototypical ferroelectric BaTiO3. Near the structural phase transitions at ∼400 K (cubic-tetragonal) and ∼280 K (tetragonal-orthorhombic), the inverse barocaloric response differs in sign and magnitude from the corresponding conventional electrocaloric response. The differences in sign arise due to the decrease in unit-cell volume on heating through the transitions, whereas the differences in magnitude arise due to the large volumetric thermal expansion on either side of the transitions.

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The electrocaloric effect around the orthorhombic- tetragonal first-order phase transition in BaTiO3

Cited by 61 publications

References 21 publications

Giant electrocaloric response in smectic liquid crystals with direct smectic-isotropic transition

Giant electrocaloric response in smectic liquid crystals with direct smectic-isotropic transition

Electrocaloric effect in BaTiO3 at all three ferroelectric transitions: Anisotropy and inverse caloric effects

Inverse barocaloric effects in ferroelectric BaTiO3 ceramics

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