Double hysteresis loops and large negative and positive electrocaloric effects in tetragonal ferroelectrics

Wu, Hong‐Hui; Zhu, Jiaming; Zhang, Tong‐Yi

doi:10.1039/c5cp02765a

Cited by 42 publications

(20 citation statements)

References 59 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In turn, depending on temperature, field strength, and strain both the conventional and inverse ECE can coexist . The coexistence of conventional and inverse ECE in one material, which has also been found in phase‐field simulations, might thus explain the partly inconsistent reports on the ECE in thin films.…”

Section: Different Examples Of Inverse Ec Responsementioning

confidence: 99%

Origins of the Inverse Electrocaloric Effect

Grünebohm

Marathe

et al. 2018

Energy Tech

View full text Add to dashboard Cite

The occurrence of the inverse (or negative) electrocaloric effect, where the isothermal application of an electric field leads to an increase in entropy and the removal of the field decreases the entropy of the system under consideration, is discussed and analyzed. Inverse electrocaloric effects have been reported to occur in several cases, for example, at transitions between ferroelectric phases with different polarization directions, in materials with certain polar defect configurations, and in antiferroelectrics. This counterintuitive relationship between entropy and applied field is intriguing and thus of general scientific interest. The combined application of normal and inverse effects has also been suggested as a means to achieve larger temperature differences between hot and cold reservoirs in future cooling devices. A good general understanding and the possibility to engineer inverse caloric effects in terms of temperature spans, required fields, and operating temperatures are thus of fundamental as well as technological importance. Here, the known cases of inverse electrocaloric effects are reviewed, their physical origins are discussed, and the different cases are compared to identify common aspects as well as potential differences. In all cases the inverse electrocaloric effect is related to the presence of competing phases or states that are close in energy and can easily be transformed with the applied field.

show abstract

Section: Different Examples Of Inverse Ec Responsementioning

confidence: 99%

Origins of the Inverse Electrocaloric Effect

Grünebohm

Marathe

et al. 2018

Energy Tech

View full text Add to dashboard Cite

show abstract

“…While typical hysteresis effects are positive, recent work has shown that negative hysteresis is far more common than may be expected. Examples of negative hysteresis in laser physics (e.g., [ 65 – 69 ]), and material science (e.g., [ 70 – 72 ]) abound. But negative hysteresis has also received increasing attention in perception, in particular in the field of ecological psychology (see e.g., [ 56 , 57 , 73 – 78 ] and also the discussion of multistability later in this paper.…”

Section: Introductionmentioning

confidence: 99%

Positive and negative hysteresis effects for the perception of geometric and emotional ambiguities

et al. 2018

View full text Add to dashboard Cite

AimThe present study utilizes perceptual hysteresis effects to compare the ambiguity of Mona Lisa’s emotional face expression (high-level ambiguity) and of geometric cube stimuli (low-level ambiguity).MethodsIn two experiments we presented series of nine Mona Lisa variants and nine cube variants. Stimulus ambiguity was manipulated by changing Mona Lisa’s mouth curvature (Exp. 1) and the cubes’ back-layer luminance (Exp. 2). Each experiment consisted of three conditions, two with opposite stimulus presentation sequences with increasing and decreasing degrees of ambiguity, respectively, and a third condition with a random presentation sequence. Participants indicated happy or sad face percepts (Exp. 1) and alternative 3D cube percepts (Exp. 2) by key presses. We studied the influences of a priori perceptual biases (long-term memory) and presentation order (short-term memory) on perception.ResultsPerception followed sigmoidal functions of the stimulus ambiguity morphing parameters. The morphing parameter for the functions’ inflection points depended strongly on stimulus presentation order with similar effect sizes but different signs for the two stimulus types (positive hysteresis / priming for the cubes; negative hysteresis / adaptation for Mona Lisa). In the random conditions, the inflection points were located in the middle between those from the two directional conditions for the Mona Lisa stimuli. For the cube stimuli, they were superimposed on one sigmoidal function for the ordered condition.DiscussionThe hysteresis effects reflect the influence of short-term memory during the perceptual disambiguation of ambiguous sensory information. The effects for the two stimulus types are of similar size, explaining up to 34% of the perceptual variance introduced by the paradigm. We explain the qualitative difference between positive and negative hysteresis with adaptation for Mona Lisa and with priming for the cubes. In addition, the hysteresis paradigm allows a quantitative determination of the impact of adaptation and priming during the resolution of perceptual ambiguities. The asymmetric shifts of inflection points in the case of the cube stimuli is likely due to an a priori perceptual bias, reflecting an influence of long-term memory. Whether corresponding influences also exist for the Mona Lisa variants is so far unclear.

show abstract

“…For instance, composites combining relaxor terpolymer P(VDF-TrFE-CFE), Ba 0.67 Sr 0.33 TiO 3 ceramics, and BNNSs show a huge electrocaloric temperature change of over 50 K at room temperature under a ultrahigh electric field of 2500 kV/cm, 134 while relaxor composites based on P(VDF-TrFE-CFE) and PMN-PT 136 are also demonstrated to be comparable to this performance (see Table I). Testifying the giant electrocaloric effect in other nanostructures such as nanoparticles, 106,111,171 nanotubes, 172 and nanowires 173 is highly desired since recent experimental results demonstrated that electrocaloric effect in polymer nanocomposites can be tailored by the morphology of the ferroelectric nanofillers. 169 As a result, the idea of using nanowires for towards wearable cooling applications has been achieved in highly bendable and stretchable Ba 0.67 Sr 0.33 TiO 3 nanowires arrays.…”

Section: Perspectivesmentioning

confidence: 99%

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

Liu

Scott

Dkhil

2016

Applied Physics Reviews

246

150

View full text Add to dashboard Cite

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

show abstract

Double hysteresis loops and large negative and positive electrocaloric effects in tetragonal ferroelectrics

Cited by 42 publications

References 59 publications

Origins of the Inverse Electrocaloric Effect

Origins of the Inverse Electrocaloric Effect

Positive and negative hysteresis effects for the perception of geometric and emotional ambiguities

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

Contact Info

Product

Resources

About