A Finemet-type alloy as a low-cost candidate for high-temperature magnetic refrigeration

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The FeCoSiAlGaPCB alloys can be prepared as bulk amorphous materials, with outstanding mechanical properties and increased electrical resistivity. These features can be beneficial for their application as a magnetic refrigerant. The influence of Co addition on the magnetic entropy change of the alloy has been studied. This compositional modification displaces the temperature of the peak entropy change closer to room temperature, but reduces the refrigerant capacity of the material. For the Co-free alloy, the peak entropy change is increased with respect to a Finemet alloy containing Mo, but its refrigerant capacity is not enhanced. © 2006 American Institute of Physics. ͓DOI: 10.1063/1.2188385͔Magnetic refrigeration is a field of research that has gained increasing attention, as it is considered an alternative to the gas compression-expansion cycle. At temperatures close to room temperature, rare-earth-based materials are among the most relevant ones. [1][2][3][4] To display a big magnetocaloric response, two requirements have to be fulfilled: the material needs to exhibit a big magnetic moment and, also, a strong temperature dependence of magnetization close to the working temperature. This second condition, related to a magnetic phase transition, can be achieved in two different ways. Either by a first-order phase transition, which produces an abrupt temperature change of the magnetic moment and, therefore, a remarkable peak in the magnetic entropy change ͑⌬S M ͒ at the transition temperature, or by a second order phase transition, which causes a more smeared peak in ⌬S M . However, the remarkable hysteresis that appears in some materials, associated to first order phase transitions, may reduce the actual efficiency of the cooling process. 5 It has been pointed out, nevertheless, that in order to compare the characteristics of different materials as candidates for magnetic refrigerants, their refrigerant capacity ͑RC͒ in a reversible cycle, connected to the entropy absorbed by the refrigerant at the cold end of the cycle and its temperature span, should be used. 6 The search for low-cost materials for high-temperature magnetic refrigeration is a field of current interest. 7-12 Recently it has been shown that some soft-magnetic amorphous alloys are good candidates for this application, 11 with a refrigerant capacity that is comparable to that of low-hysteretic Gd-based materials. 4 It has also been shown that the nanocrystallization of the alloy, although broadening the ⌬S M

“…The Cofree alloy presents a RC comparable to that of a Mo-Finemet alloy with a similar Fe content, 11 although ͉⌬S M pk ͉ and the temperature span are bigger in the present case. …”

mentioning

confidence: 59%

mentioning

confidence: 99%

Influence of Co addition on the magnetocaloric effect of FeCoSiAlGaPCB amorphous alloys

Franco

Borrego

Conde

et al. 2006

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“…They offer low magnetic hysteresis, high electrical resistivity, enhanced corrosion resistance, good mechanical properties, and tunable T C by composition variation. [4][5][6] In addition, the elements involved are abundant and fabrication costs are reasonable, making them highly competitive. Fe 80 Cr 8 B 12 amorphous alloys exhibit promising MCE near RT, Cr additions enhance the corrosion resistance of the alloy.…”

Section: Influence Of La and Ce Additions On The Magnetocaloric Effecmentioning

confidence: 99%

Influence of La and Ce additions on the magnetocaloric effect of Fe–B–Cr-based amorphous alloys

Law¹,

Franco²,

Ramanujan³

2011

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Near-room-temperature refrigeration through voltage-controlled entropy change in multiferroics Appl. Phys. Lett. 102, 031915 (2013) Resistivity, specific heat, and magnetocaloric effect of La0.8Ag0.1MnO3: Effect of isotopic substitution of 16O→ 18O Appl. Phys. Lett. 102, 032404 (2013) Giant magnetocaloric effect in Ho12Co7 compound Appl. Phys. Lett. 102, 022421 (2013) Magnetic properties and magnetocaloric effects in Er3−xGdxCo intermetallic compounds J. Appl. Phys. 113, 033908 (2013) Giant magnetocaloric and barocaloric effects in R5Si2Ge2 (R=Tb, Gd)

“…In particular, there is a growing interest in studying the applicability of soft magnetic amorphous alloys as magnetic refrigerants [9][10][11][12][13][14][15][16][17][18][19][20] due to their reduced magnetic hysteresis ͑vir-tually negligible͒, higher electrical resistivity ͑which would decrease eddy current losses͒, and tunable Curie temperature T Curie . Among the different compositional series of soft magnetic amorphous alloys, Nanoperm-type alloys are those that currently exhibit the highest RC values, having also among the highest values of ͉⌬S M pk ͉.…”

mentioning

confidence: 99%

Enhanced magnetocaloric response in Cr∕Mo containing Nanoperm-type amorphous alloys

Franco

Conde

et al. 2007

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The magnetocaloric effect of Fe76Cr8−xMoxCu1B15 (x=0,4) alloys is studied. Although the combined addition of Cr and Mo is more efficient in tuning the Curie temperature of the alloy, the Mo-free alloy presents a higher magnetocaloric response. The refrigerant capacity (RC) for the Mo-containing alloy is comparable to that of Gd5Ge1.9Si2Fe0.1 (for a field of 50kOe, RC=273Jkg−1 for the Mo alloy vs 240Jkg−1 for the Gd-based one), with a larger temperature span of the optimal refrigeration cycle (250K vs 90K, respectively). The restriction of the temperature span to 90K gives RC=187Jkg−1 for the Mo alloy. A master curve behavior for the magnetic entropy change is also evidenced.