On estimating the magnetocaloric effect from magnetization measurements

Amaral, J. S.; Amaral, V. S.

doi:10.1016/j.jmmm.2009.06.013

Cited by 178 publications

(70 citation statements)

References 18 publications

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“…The magnetocaloric effect (M CE) intrinsic to all magnetic materials is due to the coupling of the magnetic sublattice with the magnetic field [1] and can be characterized directly by measuring adiabatic change in temperature (∆T ad ) upon application of magnetic field [2,3] or indirectly from heat capacity measurements or by estimating the isothermal entropy changes (∆S M ) due to changes in applied magnetic field. Although this effect has been historically used in production of low temperatures, the discovery of giant magnetocaloric effect in Gd 5 Si 2 Ge 2 [4] has stimulated both basic and applied interest in the development of new materials that are useful for room temperature magnetic refrigeration as an alternative to vapor-compression technology [5].…”

Section: Introductionmentioning

confidence: 99%

Effect of composition on magnetocaloric properties of Mn3Ga(1−x)SnxC

Dias

Priolkar

Çakιr

et al. 2015

Journal of Applied Physics

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A study investigating the effect of Sn substitution on the magnetocaloric properties of Mn3Ga (1−x) SnxC compounds reveals that nature of the MCE has a strong dependence on the nature of the magnetic ordering. For small amounts of Sn (x ≤ 0.2) the MCE is of the inverse type wherein an increase in the applied field beyond 5T gives rise to a table like temperature dependence of the entropy due to a coupling between the first order FM -AFM transition and the field induced AFM -FM transition. Replacement of Ga by larger concentrations of Sn (x ≥ 0.71) (∆SM ) results in a change of the MCE to a conventional type with very little variation in the position of (∆SM )max with increasing magnetic field. This has been explained to be due to the local strain introduced by A site ions (Ga/Sn) which affect the magnetostructural coupling in these compounds.

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Section: Introductionmentioning

confidence: 99%

Effect of composition on magnetocaloric properties of Mn3Ga(1−x)SnxC

Dias

Priolkar

Çakιr

et al. 2015

Journal of Applied Physics

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“…(5) and (6) for the FOT is not allowed. Recently, several works proposed some approaches to apply the Maxwell relations to the FOTs, but it is still in debate [25][26][27][28][29][30][31]. Therefore, the direct measurement of MCE (ΔT ad ) is crucial to gain a deep insight into the entropic behaviour through the FOTs.…”

Section: Thermodynamics Of Mcementioning

confidence: 99%

Magnetocaloric Effects in Metamagnetic Shape Memory Alloys

Kihara¹,

Xu²,

Ito³

et al. 2017

Shape Memory Alloys - Fundamentals and Applications

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Recently, metamagnetic shape memory alloys have attracted much attention as candidates for the rare-earth free magnetic refrigerants. These materials undergo the martensitic transformation (MT) at around room temperature accompanied by a significant entropy change. The application of the magnetic field at the low-temperature martensitic phase realizes the magnetic field-induced martensitic transformation (MFIMT). Through the MFIMT, the materials show an unconventional magnetocaloric effect (MCE), which is called inverse magnetocaloric effect (IMCE). In this chapter, the direct measurement system of MCE in pulsed-high-magnetic fields is introduced. With taking the advantage of the fast field-sweep rate of pulsed field, adiabatic measurements of MCE are carried out at various temperatures. Using this technique, the IMCEs of the metamagnetic shape memory alloys NiCoMnIn and NiCoMnGa are directly measured as adiabatic temperature changes in pulsed fields. From the experimental data of MCE for NiCoMnIn, the entropy of spin system in the austenite phase is estimated through a simple mean-field model. By the combination of MCE, magnetization and specific heat measurements, the electronic, lattice and magnetic contributions to the IMCE are individually evaluated. The result for NiCoMnIn demonstrates that lattice entropy plays the dominant role for IMCE in this material.

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“…Unfortunately, the reason of such large values sometimes is an incorrect application of the Maxwell relation [32]. The conditions, under which using of the Maxwell relations is not correct in studies of MCE, are considered also in the references [33,34].…”

Section: Introductionmentioning

confidence: 99%

Direct and indirect determination of electrocaloric effect in Na0.5Bi0.5TiO3

Birks

Dunce

Peräntie

et al. 2017

Journal of Applied Physics

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Direct and indirect studies of electrocaloric effect were performed in poled and depoled Na 0.5 Bi 0.5 TiO 3 . For this purpose polarization and electrocaloric effect temperature change measurements were made at different electric field pulses as a function of temperature. Applicability of the widely-used indirect electrocaloric effect determination method, using the Maxwell relation, was critically analyzed with respect to the reliable direct measurements.Quantitative differences were observed between the results obtained by both approaches in case of the poled Na 0.5 Bi 0.5 TiO 3 sample. These differences can be explained by the temperature-dependent concentration of domains oriented in the direction of the applied electric field. Whereas in the depoled Na 0.5 Bi 0.5 TiO 3 , which is characterized by electric field dependence of polar nanoregions embedded in a nonpolar matrix, the Maxwell relation is not applicable at all, as it is indicated by the obtained results. Possible mechanisms which could be responsible for the electrocaloric effect in the relaxor state were considered. The results of this study are used to evaluate the numerous results obtained and published by other authors, using the Maxwell relation to indirectly determine electrocaloric effect. The reason of the negative electrocaloric effect values, obtained in such a way and widely discussed in literature in case of Na 0.5 Bi 0.5 TiO 3 , have been explained in this study.

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On estimating the magnetocaloric effect from magnetization measurements

Cited by 178 publications

References 18 publications

Effect of composition on magnetocaloric properties of Mn3Ga(1−x)SnxC

Effect of composition on magnetocaloric properties of Mn3Ga(1−x)SnxC

Magnetocaloric Effects in Metamagnetic Shape Memory Alloys

Direct and indirect determination of electrocaloric effect in Na0.5Bi0.5TiO3

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