The giant electrocaloric effect and high effective cooling power near room temperature for BaTiO3 thick film

Bai, Yang; Zheng, Guang; Ding, Kai; Li, Qiao; Shi, San-Qiang; Guo, Dong

doi:10.1063/1.3658251

Cited by 150 publications

(41 citation statements)

References 20 publications

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“…Different from the standard mode measuring zero-field heat capacity, modified DSC evaluates the heat flow dQ=dE by applying an electric field at a controlled temperature. 26,43,57,84,129,130,132 The electrocaloric heat can be then obtained by Q ¼ Ð E 0 ðdQ=dE 0 ÞdE 0 , which corresponds to the area of the exothermic (endothermic) peak. Therefore, the entropy change can be determined by DS ¼ Q=T.…”

Section: B Differential Scanning Calorimetry (Dsc)mentioning

confidence: 99%

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Direct and indirect measurements on electrocaloric effect: Recent developments and perspectives

Liu

Scott

Dkhil

2016

Applied Physics Reviews

236

150

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It has been ten years since the discovery of the giant electrocaloric effect in ferroelectric materials showed that it is possible to employ this effect for substantial cooling applications. This last decade has been marked by increasing research interest, especially in characterizing and measuring the electrocaloric effect using both the so-called indirect and direct approaches. In this context, a comprehensive summary and careful reexamination of these approaches are very timely and of great importance to justify the assumptions used in different measurement techniques. This review is therefore dedicated to cover recent important and rapid advances from both the indirect and direct measurements and provides critical insights relevant for quantifying the electrocaloric effect. It involves electrocaloric materials from normal ferroelectrics, antiferroelectrics, and relaxors, and it fundamentally focuses on how the electrocaloric entropy changes in response to electric field in these typical electrocalorics. The article addresses recent developments, especially during the past three years, such as technical selection of proper polarization-electric field loops, negative electrocaloric effect in antiferroelectrics and relaxors, the controversial debate on the indirect method in relaxors, the important role of field dependence of specific heat, kinetic factors, and so on. Moreover, this review also is concerned with extracting reliable data by direct measurements. Four typical techniques and devices used recently, such as thermocouples, differential scanning calorimeters, specifically designed calorimeters, and scanning thermal microscopy, are briefly reviewed, while infrared cameras are emphasized. We hope that our review will not only provide a useful background to understand fundamentally the electrocaloric effect and what one really measures but also may act as a practical guide to exploit and develop electrocalorics towards the design of suitable devices. Published by AIP Publishing. [http://dx

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Section: B Differential Scanning Calorimetry (Dsc)mentioning

confidence: 99%

“…26 Further information about various DSC setups can be found elsewhere (Refs. 26,43,57,84,129,130, and 132 and references therein].…”

Section: B Differential Scanning Calorimetry (Dsc)mentioning

confidence: 99%

Direct and indirect measurements on electrocaloric effect: Recent developments and perspectives

Liu

Scott

Dkhil

2016

Applied Physics Reviews

236

150

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“…Figure 1 compares the ΔT EC values of BaTiO 3 above T C (P r !0) calculated from Eq. (7) [23] with available experimental data [12,16,24,25]. Well-known examples of EC materials driven above the temperature of maximum dielectric permittivity are polyvinylidene fluoride terpolymers and irradiated copolymers, both exhibiting relaxor behaviour.…”

Section: Electrocaloric Effectmentioning

confidence: 99%

“…They observed that-close to the ferroelectric Curie temperature of 222 C-a field change from 77.6 to 29.5 V/μm induced an adiabatic temperature change of 12 K as it was determined from the integrated pyroelectric effect. Recently, another group showed that a lead-free stack of 63 BaTiO 3 thick films provides an EC temperature change of 7.1 K at an applied field of 80 V/ μm [16]. The thickness of the individual layers deposited by tape casting and electrically contacted by inner Ni electrodes amounted to ca.…”

Section: Introductionmentioning

confidence: 99%

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Electrocaloric Cooling

Suchaneck¹,

Pakhomov²,

Gerlach³

2017

Refrigeration

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The electrocaloric effect describes a reversible temperature change in dielectric materials submitted to an applied electric field. Adiabatic polarization raises their temperature, and adiabatic depolarization lowers it, analogous to temperature changes that occur when a gas is compressed or expanded. For refrigerator application, the reverse Brayton cycle is currently the most promising for practical implementation. The electrocaloric effect provides a large material efficiency. However, existing refrigerator prototypes lack from the absence of efficient heat switches for thermal linkage to the load and the heat sink. Cooling power densities of a few W/cm 2 and temperature spans in the order of 20 K (in regeneration systems) are achievable at a cycle time of 100 ms.Keywords: electrocaloric effect, thermodynamic cycles, coefficient of performance, refrigeration devices IntroductionFor almost 150 years, refrigeration applications were solved by means of vapour compression. While the most efficient fluids for this approach are based on chlorofluorocarbons, hydrochlorofluorocarbons and hydrofluorocarbons, they come with the severe drawback of contributing to global warming and ozone depletion. Therefore, in 1987, the Montreal Protocol issued a ban on these chemicals providing regulations for phasing them out. Promising natural alternative substances are impractical due to their toxicity (ammonia) or-in particular-their flammability (propane) [1].Vapour compression refrigerators (VCRs) are operated as reverse Rankine cycles. They use a circulating liquid refrigerant as a medium. The refrigerant is: (i) adiabatically compressed, (ii) condensed at constant pressure undergoing a phase transition (thereby rejecting heat to the heat sink), (iii) adiabatically throttled in an expansion valve and (iv) evaporated at constant © 2017 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.pressure undergoing the reverse phase transition (thereby absorbing heat from the load). The amount of transferred heat is determined by the latent heat of the first-order phase transition. Similarly, in solid-state electrocaloric (EC) cooling, the adiabatic compression/expansion of the refrigerant is analogous to adiabatic polarization/depolarization, while the isobaric processes are replaced by isofield ones. Contrary to VCR, where the adiabatic expansion of the vapour is thermodynamically irreversible, the EC and the magnetocaloric (MC) effects are thermodynamically reversible processes that could reach the limit of the Carnot efficiency. This is another aspect making them promising for future application.Electric fields required for the EC refrigeration cycle can be supplied much easier and less expensively than the high magnetic fields required for the MC refrigeration [2]. Other advantages in compar...

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A Review on Piezoelectric, Magnetostrictive, and Magnetoelectric Materials and Device Technologies for Energy Harvesting Applications

2017

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In the coming era of the internet of things (IoT), wireless sensor networks that monitor, detect, and gather data will play a crucial role in advancements in public safety, human healthcare, industrial automation, and energy management. Batteries are currently the power source of choice for operating wireless network devices due to their ease of installation; however, they require periodic replacement due to capacity limitations. Within the scope of the IoT, battery maintenance of the trillion sensor nodes that may be implemented will be practically infeasible from environmental, resource, and labor cost perspectives. In considering individual self-powered sensor nodes, the idea of harvesting energy from ambient vibrations, heat, and electromagnetic waves has recently triggered noticeable research interest in the academic community. This paper gives an overview of energy harvesting materials and systems. Three main categories are presented: piezoelectric ceramics/polymers, magnetostrictive alloys, and magnetoelectric (ME) multiferroic composites. State-of-the-art harvesting materials and structures are presented with a focus on characterization, fabrication, modeling and simulation, and durability and reliability. Some perspectives and challenges for the future development of energy harvesting materials are also highlighted.

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The giant electrocaloric effect and high effective cooling power near room temperature for BaTiO3 thick film

Cited by 150 publications

References 20 publications

Direct and indirect measurements on electrocaloric effect: Recent developments and perspectives

Direct and indirect measurements on electrocaloric effect: Recent developments and perspectives

Electrocaloric Cooling

A Review on Piezoelectric, Magnetostrictive, and Magnetoelectric Materials and Device Technologies for Energy Harvesting Applications

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