The “colossal” magnetocaloric effect in Mn1−xFexAs: What are we really measuring?

Ballı, M.; Fruchart, D.; Gignoux, D.; Zach, R.

doi:10.1063/1.3194144

Cited by 149 publications

(102 citation statements)

References 9 publications

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“…Interestingly, the calculated DS M (using increasing field) for the arc-melted LaFe 11.6 Si 1.4 compound consists of a plateau with a huge spike at 186 K, which is obviously erroneous. A similar spike was observed for Mn 1-x Fe x As, which was due to the inadequate application of the Maxwell relation in the presence of coexisting PM and FM phases [28]. However, the calculated DS M (using decreasing field) consists of a plateau with an asymmetrical distribution which is centered at T C = 186 K. The maximum values of DS M are found to be 29.8 J kg -1 K -1 for an increasing field change of 0-5T and 19.6 J kg -1 K -1 for a decreasing field change of 5 -0T.…”

Section: Resultssupporting

confidence: 60%

“…It is probable that this longer ball milling time decreased the particle size of the starting powders which effectively enhanced the formation of the 1:13 phase during sintering, consequently enhancing the magnetocaloric properties of the La(Fe x Si 1-x ) 13 alloy. The arc-melted LaFe 11.6 Si 1.4 compound from the present work exhibits a significantly higher RCP eff compared to other arc-melted LaFe 11.6 Si 1.4 compounds documented in the literature as well as the spark plasma-sintered LaFe 11.6 Si 1.4 compound from this work 28 . It is also important to note that the spark plasmasintered LaFe 11.6 Si 1.4 compound from this work displays a significantly higher RCP eff compared to arc-melted La 0.8-Gd 0.2 Fe 11.4 Si 1.6 B 0.3 compound.…”

Section: Resultssupporting

confidence: 47%

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Optimization of magnetocaloric properties of arc-melted and spark plasma-sintered LaFe11.6Si1.4

et al. 2016

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LaFe 11.6 Si 1.4 alloy has been synthesized in polycrystalline form using both arc melting and spark plasma sintering (SPS). The phase formation, hysteresis loss and magnetocaloric properties of the LaFe 11.6 Si 1.4 alloys synthesized using the two different techniques are compared. The annealing time required to obtain the 1:13 phase is significantly reduced from 14 days (using the arc melting technique) to 30 min (using the SPS technique). The magnetic entropy change (DS M ) for the arc-melted LaFe 11.6 Si 1.4 compound, obtained for a field change of 5 -0T (decreasing field), was estimated to be 19.6 J kg -1 K -1 . The effective RCP at 5T of the arc-melted LaFe 11.6 Si 1.4 compound was determined to be 360 J kg -1 which corresponds to about 88 % of that observed in Gd. A significant reduction in the hysteretic losses in the SPS LaFe 11.6 Si 1.4 compound was observed. The DS M , obtained for a field change of 5 -0T (decreasing field), for the SPS LaFe 11.6 Si 1.4 compound decreases to 7.4 J kg -1 K -1 . The T C also shifts from 186 (arc-melted) to 230 K (SPS) and shifts the order of phase transition from first to second order, respectively. The MCE of the SPS LaFe 11.6 Si 1.4 compound spreads over a larger temperature range with the RCP value at 5T reaching 288 J kg -1 corresponding to about 70 % of that observed in Gd. At low fields, the effective RCP values of the arc-melted and spark plasma-sintered LaFe 11.6 Si 1.4 compounds are comparable, thereby clearly demonstrating the potential of SPS LaFe 11.6 Si 1.4 compounds in low-field magnetic refrigeration applications.

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Section: Resultssupporting

confidence: 60%

Section: Resultssupporting

confidence: 47%

Optimization of magnetocaloric properties of arc-melted and spark plasma-sintered LaFe11.6Si1.4

et al. 2016

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“…With increasing magnetic field, the ∆S peak gradually expands toward lower temperatures because of the field-induced metamagnetic transition behavior, and a wide span of ∆S appears. The maximal effective ∆S (the high plateau, not the spike [72,73] ) is about 21 J·kg −1 ·K −1 near T M C ∼ 285 K, and the temperature span of ∆S reaches 15 K under a field change of 0-5 T. This ∆S is much larger than that of the traditional refrigerant Gd. [42,43] …”

Section: Magnetic Entropy Change In Conventional Nimn-based Heusler Amentioning

confidence: 87%

“…Figures 18(c) and 18(d) show the ∆S curves calculated by using Maxwell's equations. The effective ∆S (not the spike, but the high plateau value [72,73] ) is 19.5 J·kg −1 ·K −1 (∼ 269 K) and 18.7 J·kg −1 ·K −1 (∼ 281 K) under a field change of 0-5 T for x = 0 and 0.05 samples, respectively. Note that the effective ∆S is nearly unchanged upon Fe doping, and the effective refrigerator capacity of the Fe-doped sample (x = 0.05) is enhanced by ∼ 15% compared to that of its mother compound due to the reduction of the hysteresis loss.…”

Section: -10mentioning

confidence: 95%

“…15 are the ∆S curves obtained by using Maxwell's relations. The effective inverse ∆S (the plateau height, not the spike [72,73] ) is about ∼ 20 J·kg −1 ·K −1 , ∼ 17 J·kg −1 ·K −1 , and ∼ 15 J·kg −1 ·K −1 , and the corresponding half-peak width is ∼ 20 K, ∼ 27 K, and ∼ 34 K, for the as-prepared, 250 • C-annealed, and 300 • C-annealed Ni 45 Co 5 Mn 36.7 In 13.3 samples, respectively. Although the magnitude of the effective ∆S is somewhat reduced, the temperature span is broadened.…”

Section: -10mentioning

confidence: 99%

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Magnetic entropy change involving martensitic transition in NiMn-based Heusler alloys

Hu¹,

Shen²,

Sun³

2013

Chinese Phys. B

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Our recent progress on magnetic entropy change (∆S) involving martensitic transition in both conventional and metamagnetic NiMn-based Heusler alloys is reviewed. For the conventional alloys, where both martensite and austenite exhibit ferromagnetic (FM) behavior but show different magnetic anisotropies, a positive ∆S as large as 4.1 J·kg −1 ·K −1 under a field change of 0-0.9 T was first observed at martensitic transition temperature T M ∼ 197 K. Through adjusting the Ni:Mn:Ga ratio to affect valence electron concentration e/a, T M was successfully tuned to room temperature, and a large negative ∆S was observed in a single crystal. The −∆S attained 18.0 J·kg −1 ·K −1 under a field change of 0-5 T. We also focused on the metamagnetic alloys that show mechanisms different from the conventional ones. It was found that post-annealing in suitable conditions or introducing interstitial H atoms can shift the T M across a wide temperature range while retaining the strong metamagnetic behavior, and hence, retaining large magnetocaloric effect (MCE) and magnetoresistance (MR). The melt-spun technique can disorder atoms and make the ribbons display a B2 structure, but the metamagnetic behavior, as well as the MCE, becomes weak due to the enhanced saturated magnetization of martensites. We also studied the effect of Fe/Co co-doping in Ni 45 (Co 1−x Fe x ) 5 Mn 36.6 In 13.4 metamagnetic alloys. Introduction of Fe atoms can assist the conversion of the Mn-Mn coupling from antiferromagnetic to ferromagnetic, thus maintaining the strong metamagnetic behavior and large MCE and MR. Furthermore, a small thermal hysteresis but significant magnetic hysteresis was observed around T M in Ni 51 Mn 49−x In x metamagnetic systems, which must be related to different nucleation mechanisms of structural transition under different external perturbations.

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Tuning the Reversible Magnetocaloric Effect in Ni–Mn–In‐Based Alloys through Co and Cu Co‐Doping

Yang

Liu

et al. 2019

Adv Elect Materials

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The reversibility of the giant magnetocaloric effect (MCE) through the magnetic field–induced magnetostructural transformation in Ni–Mn–In‐based alloys is a key issue towards the potential magnetic refrigeration applications. In this work, Co and Cu are simultaneously doped to tune the reversible magnetocaloric properties associated with the magnetostructural transformation. Owing to the integration of large magnetization difference ΔM, suitable transformation entropy ΔStr, and narrow thermal hysteresis ΔThys in a Ni46Co3Mn35Cu2In14 alloy, the reversible field–induced inverse martensitic transformation is realized in a wide temperature range of 30 K under the field of 5T, yielding a maximum reversible magnetic entropy change ΔSMmax of 16.4 J kg−1 K−1. Moreover, under a low field change of 1.5T, a large reversible adiabatic temperature variation ΔTad of 2.5 K is also obtained, representing the highest value so far under the low field change of 1.5T in Ni–Mn‐based alloys. It is demonstrated that multi‐component alloying by combining the effects of appropriate substitutional elements is an effective way to develop high‐performance magnetocaloric materials.

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The “colossal” magnetocaloric effect in Mn1−xFexAs: What are we really measuring?

Cited by 149 publications

References 9 publications

Optimization of magnetocaloric properties of arc-melted and spark plasma-sintered LaFe11.6Si1.4

Optimization of magnetocaloric properties of arc-melted and spark plasma-sintered LaFe11.6Si1.4

Magnetic entropy change involving martensitic transition in NiMn-based Heusler alloys

Tuning the Reversible Magnetocaloric Effect in Ni–Mn–In‐Based Alloys through Co and Cu Co‐Doping

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