Caloric materials near ferroic phase transitions

Moya, Xavier; Kar‐Narayan, Sohini; Mathur, N. D.

doi:10.1038/nmat3951

Cited by 1,172 publications

(1,067 citation statements)

References 144 publications

(165 reference statements)

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“…It is interesting to note that the magnitude of the eC responsivity in LCE of ≈4 K MPa −1 is two orders of magnitude larger than the average eC responsivity of ≈0.04 K MPa −1 found in the best shape memory alloys [10]. …”

Section: Elastocaloric Effect In Main-chain Liquid Crystal Elastomer:mentioning

confidence: 79%

Electrocaloric and elastocaloric effects in soft materials

Trček

Lavrič

Cordoyiannis

et al. 2016

Phil. Trans. R. Soc. A.

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Materials with large caloric effect have the promise of realizing solid-state refrigeration which has potential to be more efficient and environmentally friendly compared with current cooling technologies. Recently, the focus of caloric effects investigations has shifted towards soft materials. An overview of recent direct measurements of the large electrocaloric effect (ECE) in a composite mixture of a liquid crystal and nanoparticles (NPs) and large elastocaloric (eC) effect in main-chain liquid crystal elastomers is given. In mixtures of 12CB liquid crystal with functionalized CdSSe NPs, an ECE exceeding 5 K was found in the vicinity of the isotropic to smectic A phase transition. It is shown that the NPs smear the isotropic to smectic coexistence range in which a large ECE is observed due to latent heat enhancement. NPs acting as traps for ions reduce the moving-ion density and consequently the Joule heating. Direct eC measurements indicate that the significant eC response can be found in main-chain liquid crystalline elastomers, but at a fraction of the stress field in contrast to other eC materials. Both soft materials could play a significant role as active cooling elements or parts of thermal diodes in development of new cooling devices. This article is part of the themed issue ‘Taking the temperature of phase transitions in cool materials’.

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Section: Elastocaloric Effect In Main-chain Liquid Crystal Elastomer:mentioning

confidence: 79%

Electrocaloric and elastocaloric effects in soft materials

Trček

Lavrič

Cordoyiannis

et al. 2016

Phil. Trans. R. Soc. A.

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“…In addition, applying more than one species of driving field to the ferroic materials is considered as an effective way to extend the working temperature region of solid-state refrigeration as well. 1,5,11,12 However, according to the earlier reports, the phase transition temperature is shifted several Kelvins with the coaction of external fields, 13 ability of broadening the refrigeration temperature region. Therefore, the narrow working temperature region is still a challenge for the caloric refrigeration.…”

Section: All Article Content Except Where Otherwise Noted Is Licensmentioning

confidence: 95%

“…[1][2][3][4][5][6][7] By applying external stimulus, such as magnetic, electric, or stress fields on these ferroic materials, the corresponding caloric effects, such as magnetocaloric (MC), electrocaloric (EC), and elastocaloric (eC) effects, would be obtained, for ferromagnets, ferroelectrics, and ferroelastics, respectively. 1,5,6 However, the refrigeration temperature regions of most caloric effects are usually in a limited scale due to the narrow phase transition region of ferroic materials, which has been a key drawback for applications. 2,8 In order to solve this problem, some alternative solutions are proposed.…”

Section: All Article Content Except Where Otherwise Noted Is Licensmentioning

confidence: 99%

Combined caloric effects in a multiferroic Ni–Mn–Ga alloy with broad refrigeration temperature region

Yang

et al. 2017

APL Materials

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Solid-state refrigeration based on the caloric effects is promising to replace the traditional vapor-compressing refrigeration technology due to environmental protection and high efficiency. However, the narrow working temperature region has hindered the application of these refrigeration technologies. In this paper, we propose a method of combined caloric, through which a broad refrigeration region can be realized in a multiferroic alloy, Ni–Mn–Ga, by combining its elastocaloric and magnetocaloric effects. Moreover, the materials’ efficiency of elastocaloric effect has been greatly improved in our sample. These results illuminate a promising way to use multiferroic alloys for refrigeration with a broad refrigeration temperature region.

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“…Moreover, since entropic changes involving evolution of other ferroic order parameters can be cumulative with the EC effect, more advanced multicaloric materials concepts blending polar, magnetic and elastic energy-interconversion functionalities, are also being considered. [20][21][22][23][24] Here we use a multiscale computational approach that combines ab initio quantum mechanical simulations, phenomenological Landau theory and thermodynamical evaluations to investigate the EC response of a 'material template' based on a quasi-two-dimensional system that exhibits polar Goldstone-like [25][26][27] excitations. This template system is an 'n = 2' Ruddlesden-Popper (RP) type 28 PbSr 2 Ti 2 O 7 (PSTO) layered-oxide superlattice shown in Figure 1a.…”

Section: Introductionmentioning

confidence: 99%

Amplitudon and phason modes of electrocaloric energy interconversion

et al. 2016

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Solid-state electrothermal energy interconversion utilising the electrocaloric effect is currently being considered as a viable source of applications alternative to contemporary cooling and heating technologies. Electrocaloric performance of a dielectric system is critically dependent on the number of uncorrelated polar states, or 'entropy channels' present within the system phase space. Exact physical origins of these states are currently unclear and practical methodologies for controlling their number and creating additional ones are not firmly established. Here we employ a multiscale computational approach to investigate the electrocaloric response of an artificial layered-oxide material that exhibits Goldstone-like polar excitations. We demonstrate that in the low-electric-field poling regime, the number of independent polar states in this system is proportional to the number of grown layers, and that the resulting electrocaloric properties are tuneable in the whole range of temperatures below T C by application of electric fields and elastic strain. INTRODUCTION Electrocaloric (EC) effect is defined as the variation of the dielectric material entropy as a function of the electric field at a given temperature, which results in an adiabatic temperature change. Recently, there has been significant progress 1-3 in the development of polar (i.e., possessing spontaneous polarisation) dielectrics that display large EC temperature shifts ΔT under electric-field poling. These systems include a variety of ferroelectric ceramics, 4-6 polymers 7-10 and liquid crystals. 11 A few relaxor and antiferroelectric materials may exhibit negative EC effect, which is especially advantageous for solid-state refrigeration. 12 The best values of positive EC ΔT in modern nanoengineered materials range from 20 to 45 K, for electric-field sweeps ΔE ⩾ 500 kV/cm, 1-6,13,14 whereas negative EC ΔT remain below − 10 K for much smaller ΔE. [15][16][17][18] The magnitude of the EC ΔT is proportional to a logarithm of the number of possible polar states, or independent 'entropy channels' in the system. 3,19 Therefore, it is highly desirable to acquire precise understanding of physical phenomena underpinning the emergence of these states and develop practical methods for engineering additional entropy channels into dielectrics. Moreover, since entropic changes involving evolution of other ferroic order parameters can be cumulative with the EC effect, more advanced multicaloric materials concepts blending polar, magnetic and elastic energy-interconversion functionalities, are also being considered. [20][21][22][23][24] Here we use a multiscale computational approach that combines ab initio quantum mechanical simulations, phenomenological Landau theory and thermodynamical evaluations to investigate the EC response of a 'material template' based on a quasi-two-dimensional system that exhibits polar Goldstone-like [25][26][27] excitations. This template system is an 'n = 2' Ruddlesden-Popper (RP) type 28 PbSr 2 Ti 2 O 7 (PSTO) layered-oxide

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Caloric materials near ferroic phase transitions

Cited by 1,172 publications

References 144 publications

Electrocaloric and elastocaloric effects in soft materials

Electrocaloric and elastocaloric effects in soft materials

Combined caloric effects in a multiferroic Ni–Mn–Ga alloy with broad refrigeration temperature region

Amplitudon and phason modes of electrocaloric energy interconversion

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