Large reversible magnetocaloric effect in Ni-Mn-In-Co

Gottschall, Tino; Skokov, Konstantin P.; Frincu, Bianca; Gutfleisch, Oliver

doi:10.1063/1.4905371

Cited by 190 publications

(96 citation statements)

References 18 publications

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“…This parameter depends on both the temperature and magnetic field. In the present work, the diverse excitations (temperature and magnetic field) driving the martensitic transition of a Ni-Mn-InCo Heusler alloy with the giant magnetocaloric effect 9 are considered through an effective temperature, T*, which depends on the magnetic moment and the entropy of the transition. Unlike the previous models, this phenomenological approach simplifies the picture of the transition with a Published by AIP Publishing.…”

mentioning

confidence: 99%

A unified approach to describe the thermal and magnetic hysteresis in Heusler alloys

Blázquez

Franco

Conde

et al. 2016

Applied Physics Letters

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Different excitations, like temperature, magnetic field, or pressure, can drive a martensitic transition in Heusler alloys. Coupled phenomena in these materials lead to interesting magnetocaloric and barocaloric effects ascribed to this transition. In this work, we demonstrate that isothermal transformations induced by a magnetic field and isofield transformations induced by the temperature can be described using the same framework. By defining an effective temperature that relates field and temperature through the properties of the system (magnetic moment and entropy of the transition), both kinds of loops can be transformed into the other kind, therefore providing a more effective way of characterizing hysteretic samples. The validity of this effective temperature approach to describe the transition holds for martensite to austenite transformations as well as reversal ones, and thus, the hysteresis phenomena can be described using this single general excitatio

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mentioning

confidence: 99%

A unified approach to describe the thermal and magnetic hysteresis in Heusler alloys

Blázquez

Franco

Conde

et al. 2016

Applied Physics Letters

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“…This pronounced asymmetry between heating and cooling is not reported for bulk polycrystalline samples . We propose that the presence of large angle grain boundaries, occurring in polycrystalline bulk, but not in the present epitaxial films, act as nucleation sites for the forward transformation to the martensite.…”

Section: Discussionmentioning

confidence: 42%

“…To influence and decrease thermal hysteresis in Heusler alloys, different approaches were proposed: 1) the use of artificial phase nucleation sites, 2) training by thermal cycling, and 3) minor loops …”

Section: Introductionmentioning

confidence: 99%

Reducing Hysteresis Losses by Heating Minor Loops in Magnetocaloric Ni–Mn–Ga–Co Films

et al. 2018

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Magnetocaloric materials relying on first‐order phase transitions give the highest entropy changes compared to second‐order transitions. However, they have the drawback of a transformation hysteresis, which reduces the efficiency of a cooling cycle. Here an approach to reduce the thermal hysteresis losses by performing incomplete transformation cycles, so called minor loops, is presented. A freestanding, epitaxially grown Ni–Mn–Ga–Co film is used as a model system to analyze the direct martensitic and reverse transformation paths in detail. The additional residual phase fraction only facilitates the forward martensitic transformation, but not the reverse transformation. This pronounced asymmetry between cooling and heating demonstrates that the forward transformation to martensite is controlled by nucleation and the associated excess energy contributes to hysteresis losses. For the reverse transformation, however, nuclei of austenite are always present and accordingly this transformation is controlled by growth of the austenitic phase. The experiments reveal that only the use of heating minor loops is useful to improve the efficiency of magnetocaloric epitaxial films and by this, the ratio of usable magnetization difference divided by hysteresis loss can be increased by 64 %.

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“…For this reason, much research has focused on narrowing thermal hysteresis and operating within a minor loop of the hysteresis, where only a partial conversion between phases is performed. 6,[19][20][21] The phase transition involves a significant volume change, which poses a challenge for engineering a device that must withstand continuous, rapid cycling. 2,22 This challenge was acknowledged by Singh et al, who explored the system Mn 1+x Ni 2 In 1−x (x < 0.4) aiming to increase ∆S M by increasing magnetization without driving a first-order transition.…”

Section: Introductionmentioning

confidence: 99%

Tuning the magnetocaloric response in half-Heusler/Heusler MnNi1+xSb solid solutions

Levin

Bocarsly

Wyckoff

et al. 2017

Phys. Rev. Materials

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Materials with a large magnetocaloric response are associated with a temperature change upon the application of a magnetic field, and are of interest for applications in magnetic refrigeration and thermomagnetic power generation. The usual metric of this response is the gravimetric isothermal entropy change ∆SM . The use of a simple proxy for the ∆SM that is based on density functional theory (DFT) calculations of the magnetic electronic structure, suggests that half-Heusler MnNiSb should be a better magnetocaloric than the corresponding Heusler compound MnNi2Sb. Guided by this observation, we present a study of MnNi1+xSb (x = 0, 0.25, 0.5, 0.75, 1.0) to evaluate relevant structural and magnetic properties. DFT stability calculations suggest that the addition of Ni takes place at a symmetrically distinct Ni site in the half-Heusler structure, and support the observation using synchrotron X-ray diffraction of a homogeneous solid solution between the half-Heusler and Heusler endmembers. There is a maximum in the saturation magnetization at x = 0.5, and the Curie temperature systematically decreases with increasing x. ∆SM for a maximum magnetic field change of ∆H = 5 T monotonically decreases in magnitude from −2.93 J kg −1 K −1 in the half-Heusler to −1.35 J kg −1 K −1 in the Heusler compound. The concurrent broadening of the magnetic transition results in a maximum in the refrigerant capacity at x = 0.75. The Curie temperature of this system is highly tunable between 350 K and 750 K, making it ideal for low grade waste heat recovery via thermomagnetic power generation. The increase in ∆SM with decreasing x may be extendable to other MnNi2Z Heusler systems that are currently under investigation for use in magnetocaloric refrigeration applications.

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Large reversible magnetocaloric effect in Ni-Mn-In-Co

Cited by 190 publications

References 18 publications

A unified approach to describe the thermal and magnetic hysteresis in Heusler alloys

A unified approach to describe the thermal and magnetic hysteresis in Heusler alloys

Reducing Hysteresis Losses by Heating Minor Loops in Magnetocaloric Ni–Mn–Ga–Co Films

Tuning the magnetocaloric response in half-Heusler/Heusler MnNi1+xSb solid solutions

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