Caloric effects in ferroic materials

Fähler, Sebastian; Pecharsky, V. K.

doi:10.1557/mrs.2018.66

Cited by 65 publications

(35 citation statements)

References 26 publications

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“…In the struggle to cover the growing demand for airconditioning and refrigeration, solid-state-cooling with ferroic materials offers a promising, environment-friendly and energy-efficent alternative to the prevailing gascompressor scheme (see Ref. 1 and references therein for a recent overview). Here, heat transport is realized, with the help of a ferroelastic, ferroelectric or ferromagnetic solid being driven through a (preferentially first-order) phase transition under cyclic application and release of an external field.…”

Section: Introductionmentioning

confidence: 99%

Determining the vibrational entropy change in the giant magnetocaloric material LaFe11.6Si1.4 by nuclear resonant inelastic x-ray scattering

et al. 2018

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Magnetocaloric LaFe13−xSix-based compounds belong to the outstanding materials with potential for efficient solid-state refrigeration. We have performed temperature-dependent 57 Fe nuclear resonant inelastic X-ray scattering measurements (in a field µ0H of ∼ 0.7 T) of the vibrational (phonon) density of states, VDOS, in LaFe11.6Si1.4 across the metamagnetic isostructural first-order phase transition at TC ∼ 192 K from the low-temperature ferromagnetic (FM) to the high-temperature paramagnetic (PM) phase, in order to determine the change in thermodynamic properties of the Fe lattice at TC . The experimental results are compared with density-functional-theory (DFT)-based first-principles calculations using the fixed-spin moment (FSM) approach. Our combined experimental and theoretical results reveal distinct and abrupt changes in the VDOS of the Fe sublattice across TC , occurring within a small temperature interval of ∆T ≤ 12 K around TC . This indicates that strong magnetoelastic coupling (at the atomic scale) is present up to TC , leading to a pronounced lattice softening (phonon red-shift) in the PM phase. These changes originate from the itinerant electron magnetism associated with Fe and are correlated with distinct modifications in the Fe-partial electronic density of states, D(EF ), at the Fermi energy, EF . From the experimental VDOS we can infer an abrupt increase (jump) in the Fe-partial vibrational entropy ∆S vib of + 6.9 ± 2.6 J/(kg K) and in the vibrational specific heat ∆C vib of + 2.7 ± 1.6 J/(kg K) upon heating. The increase in magnitude of the vibrational entropy |∆S vib |= 6.9 J/(kg K) of the Fe sublattice at TC upon heating is substantial, if compared with the magnitude of the isothermal entropy change |∆Siso| of 14.2 J/(kg K) in a field change ∆B from 0 to 1 T, as obtained from isothermal magnetization measurements on our sample and using the Maxwell relation. We demonstrate that ∆S vib obtained by NRIXS is a sizable quantity and contributes directly and cooperatively to the total entropy change ∆Siso at the phase transition of LaFe13−xSix. * Corresponding author. Electronic address:

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Section: Introductionmentioning

confidence: 99%

Determining the vibrational entropy change in the giant magnetocaloric material LaFe11.6Si1.4 by nuclear resonant inelastic x-ray scattering

et al. 2018

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“…An extended introduction in ferroic cooling as well as to the particular magnetocaloric materials and devices, electrocaloric, elastocaloric and multicaloric effects can be found in another recent special issue. The present issue goes even more into depth and addresses all aspects, which range from the fundamentals towards application.…”

Section: Figurementioning

confidence: 99%

“…Forf erroic cooling, first-and second-order phase transitions are both relevant.F irst-orderp hase transitions can result in huge entropy changes,b ut these materials are only suitable in an arrow temperature range around the transition temperature.I na ddition, the associated hysteresisl osses reduce the cooling efficiency.S econd-order phase transitions exhibit no hysteresis,b ut commonly only reach al ower entropy change,w hicha dvantageously can be used within a broader temperature range.T he dispute between first-and second-order phase transitions in ferroic cooling is covered in depth within ar ecent Special Issue on hysteresis. [3] An extended introductioni nf erroic cooling [4] as well as to the particular magnetocaloric materials [5] and devices, [6] electrocaloric, [7] elastocaloric [8,9] and multicaloric effects [10] can be found in another recents pecial issue.T he present issue goes even more into depth and addresses all aspects,w hich range from the fundamentals towards application. It answers most of the questionsa sked at the beginning of the interdisciplinary priorityp rogram FerroicCooling (SPP 1599).…”

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confidence: 99%

Caloric Effects in Ferroic Materials: New Concepts for Cooling

Fähler

2018

Energy Tech

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Refrigeration is one of the primary uses for electrical energy and an important contributor to worldwide CO2 emissions. Both of these issues can be mitigated if caloric effects in solid materials are fully utilized. In particular, materials with ferroic phase transitions, which give rise to magneto‐, electro‐, and elasto‐caloric effects, are promising candidates. Because these refrigerants are in the solid state, the corresponding cooling technology also eliminates the need for halo‐carbon refrigerants with high global warming potential. This Special Issue gives an overview on recent breakthroughs in the research on magnetocaloric, elastocaloric, and electrocaloric materials and their implementation in more efficient cooling devices, as obtained within the German Priority Program Ferroic Cooling (SPP 1599). As a brief introduction to the in‐depth Reviews and Full Papers included in the Special Issue, a ferroic cooling cycle is sketched and the influences of magnetic, electric, and stress fields on ferroic materials are summarized in this Editorial.

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“…[8,9] The ECE is also the basis for the temperature-mediated magnetoelectric coupling which was proposed recently. [1,9] Indeed, the majority of large caloric effects reported so far occur in ferroics, especially ones that undergo structural first-order phase transitions. [1,9] Indeed, the majority of large caloric effects reported so far occur in ferroics, especially ones that undergo structural first-order phase transitions.…”

Section: Introductionmentioning

confidence: 99%

Unveiling Electrocaloric Potential of Antiferroelectrics with Phase Competition

Kingsland

Lisenkov

Ponomareva

2018

Advcd Theory and Sims

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Currently, the electrocaloric effect (ECE) is considered for applications in solid-state refrigeration. Direct semi-classical first-principles-based simulation to the case of ultra-thin PbZrO 3 films in order to unveil the unusual electrocaloric potential of antiferroelectrics with phase competition are applied. Strong enhancement of the ECE in the vicinity of the antiferroelectric-ferroelectric phase transition, the coexistence of electric-field tunable positive and negative ECE in antiferroelectrics, and a large ECE in the vicinity of lossless antipolar-polar phase transitions are predicted. Direct simulations demonstrate that phase switching, which occurs with hysteretic losses, gives rise to the irreversible heating which is explained using basic thermodynamics. A refrigeration cycle that tames the irreversible heating is proposed, tested in direct simulations, and found to outperform the conventional cycle based on fully reversible processes. Furthermore, direct simulations reveal critical misconceptions in the application of the controversial indirect approach to the case of ferroics with electric hysteresis. The route to overcoming the uncertainties with this dominant ECE investigation approach is proposed.

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Caloric effects in ferroic materials

Abstract: Abstract

Cited by 65 publications

References 26 publications

Determining the vibrational entropy change in the giant magnetocaloric material LaFe11.6Si1.4 by nuclear resonant inelastic x-ray scattering

Determining the vibrational entropy change in the giant magnetocaloric material LaFe11.6Si1.4 by nuclear resonant inelastic x-ray scattering

Caloric Effects in Ferroic Materials: New Concepts for Cooling

Unveiling Electrocaloric Potential of Antiferroelectrics with Phase Competition

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