Magnetic Moment of Cu-Modified Ni2MnGa Magnetic Shape Memory Alloys

Kanomata, T.; Endo, Kojin; Kudo, Naoto; Umetsu, Rie Y.; Nishihara, H.; Kataoka, Masatoshi; Nagasako, Makoto; Kainuma, Ryosuke; Ziebeck, K.R.A.

doi:10.3390/met3010114

Cited by 18 publications

(11 citation statements)

References 28 publications

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“…Moreover, the Curie temperature of the martensite phase (T C,M ) is slightly higher or almost equal to the Curie temperature of the parent phase (T C,P ), and the ΔM in the vicinity of martensitic transformation temperature (T M s ) is very small. Similar phase diagrams can be found for Ni-Mn-Ga systems such as in Ni 2+x Mn 1−x Ga [30][31][32] and other sections [33,34] [36], Ni-Mn-Ga-Cu [37][38][39], and Ni-Mn-Ga-Fe [40,41] systems also show similar behaviors, and a magnetically coupled structural transition, i.e., a direct transition from region I to region IV, can be found in a wide range of compositions.…”

Section: Introductionsupporting

confidence: 53%

Thermodynamics and Kinetics of Martensitic Transformation in Ni-Mn-based Magnetic Shape Memory Alloys

Kainuma

Kihara

et al. 2015

MATEC Web of Conferences

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Abstract. We herein present a review of recent thermodynamic and kinetic studies on Ni-Mn-based magnetic shape memory alloys along with some new data supporting the kinetic discussion. Magnetic phase diagrams and Clausius-Clapeyron relationships are mainly discussed for Ni-Mn-Ga and Ni-Mn-In systems. For the kinetics, a phenomenological model based on Seeger's model is used to describe the temperature dependence of magnetic field hysteresis, as well as the change of hysteresis under different sweeping rates of magnetic fields.

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Section: Introductionsupporting

confidence: 53%

Thermodynamics and Kinetics of Martensitic Transformation in Ni-Mn-based Magnetic Shape Memory Alloys

Kainuma

Kihara

et al. 2015

MATEC Web of Conferences

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“…As expected for the positive magnetization jump upon forward MT, the transformation temperatures rise with the increasing applied field, as shown in the insets of Figure 7. The magnetization jumps stabilize above 3 T, at about 28 emu/g for x = 6 and 18 emu/g for x = 7, and consequently with the decrease in saturation magnetization observed for the increasing Cu content [27]. These data, combined in Equation 1with the entropy values quoted above, lead to (dT/dH) rates of 0.8 K/T and 0.9 K/T for x = 6 and x = 7, respectively, which do not differ much from those obtained experimentally, 1.0 K/T and 1.1 K/T, as shown in the insets of Figure 7.…”

Section: Magnetostructural Transition Under Applied Fieldmentioning

confidence: 82%

Optimizing the Caloric Properties of Cu-Doped Ni–Mn–Ga Alloys

et al. 2020

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With the purpose to optimize the functional properties of Heusler alloys for their use in solid-state refrigeration, the characteristics of the martensitic and magnetic transitions undergone by Ni50Mn25−xGa25Cux (x = 3–11) alloys have been studied. The results reveal that, for a Cu content of x = 5.5–7.5, a magnetostructural transition between paramagnetic austenite and ferromagnetic martensite takes place. In such a case, magnetic field and stress act in the same sense, lowering the critical combined fields to induce the transformation; moreover, magnetocaloric and elastocaloric effects are both direct, suggesting the use of combined fields to improve the overall refrigeration capacity of the alloy. Within this range of compositions, the measured transformation entropy is increased owing to the magnetic contribution to entropy, showing a maximum at composition x = 6, in which the magnetization jump at the transformation is the largest of the set. At the same time, the temperature hysteresis of the transformation displays a minimum at x = 6, attributed to the optimal lattice compatibility between austenite and martensite. We show that, among this system, the optimal caloric performance is found for the x = 6 composition, which displays high isothermal entropy changes (−36 J·kg−1·K−1 under 5 T and −8.5 J·kg−1·K−1 under 50 MPa), suitable working temperature (300 K), and low thermal hysteresis (3 K).

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“…Substitution at the Ga site by either Fe, Co or Cu shows a trend of rapid increase in T m and slow decrease of T c , resulting in them coinciding for the concentration of the substituting element in the range of 10-20%. [22][23][24] These outcomes, thus, prove that the structure-property relationships in Ni-Mn-Ga based system delicately depend on the substituting element, the substituent and the composition.…”

Section: Introductionmentioning

confidence: 80%

“…Substitution at Mn site, on the other hand, produced results depending upon the substituting element. While substitution of Mn by Co or Cu elevates T m and reduces T c as the concentration of the substituting element increases, [20][21][22] T m is observed to decrease as a function of Fe concentration when Fe is substituted at Mn site. Substitution at the Ga site by either Fe, Co or Cu shows a trend of rapid increase in T m and slow decrease of T c , resulting in them coinciding for the concentration of the substituting element in the range of 10-20%.…”

Section: Introductionmentioning

confidence: 99%

Effect of Fe and Co substitution on the martensitic stability and the elastic, electronic, and magnetic properties ofMn2NiGa: Insights fromab initiocalculations

Kundu

Ghosh

2017

Phys. Rev. B

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We investigate the effects of Fe and Co substitutions on the phase stability of the martensitic phase, mechanical, electronic and magnetic properties of magnetic shape memory system Mn2NiGa by first-principles Density functional theory(DFT) calculations. The evolution of these aspects upon substitution of Fe and Co at different crystallographic sites are investigated by computing the electronic structure, mechanical properties (tetragonal shear constant, Pugh ratio and Cauchy pressure) and magnetic exchange parameters. We find that the martensitic phase of Mn2NiGa gradually de-stabilises with increase in concentration of Fe/Co due to the weakening of the minority spin hybridisation of Ni and Mn atoms occupying crystallographically equivalent sites. The interplay between relative structural stability and the compositional changes are understood from the variations in the elastic modulii and electronic structures. We find that like in the Ni2MnGa-based systems, the elastic shear modulus C can be considered as a predictor of composition dependence of martensitic transformation temperature Tm in substituted Mn2NiGa, thus singling it out as the universally acceptable predictor for martensitic transformation in Ni-Mn-Ga compounds over a wide composition range. The magnetic properties of Mn2NiGa are found to be greatly improved by the substitutions due to stronger ferromagnetic interactions in the compounds. The gradually weaker(stronger) Jahn-Teller distortion (covalent bonding) in the minority spin densities of states due to substitutions lead to a half-metallic like gap in these compounds resulting in materials with high spin-polarisation when the substitutions are complete. The substitutions at the Ga site result in two new compounds Mn2NiFe and Mn2NiCo with very high magnetic moments and Curie temperatures. Thus, our work indicates that although the substitutions de-stabilise the martensitic phase in Mn2NiGa, new magnetic materials with very good magnetic parameters and potentially useful for novel magnetic applications can be obtained. This can trigger interests in the experimental community for further research on substituted Mn2NiGa.

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Magnetic Moment of Cu-Modified Ni2MnGa Magnetic Shape Memory Alloys

Cited by 18 publications

References 28 publications

Thermodynamics and Kinetics of Martensitic Transformation in Ni-Mn-based Magnetic Shape Memory Alloys

Thermodynamics and Kinetics of Martensitic Transformation in Ni-Mn-based Magnetic Shape Memory Alloys

Optimizing the Caloric Properties of Cu-Doped Ni–Mn–Ga Alloys

Effect of Fe and Co substitution on the martensitic stability and the elastic, electronic, and magnetic properties ofMn2NiGa: Insights fromab initiocalculations

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