Rare‐Earth‐Free Mn₃₀Fe_20−xCu_xAl₅₀ Magnetocaloric Materials with Stable Cubic CsCl‐Type Structure for Room‐Temperature Refrigeration

Abstract

Magnetic refrigeration technology based on the magnetocaloric effect (MCE) of magnetic substances has been considered a prominent, energy‐efficient, and environmentally benign cooling method. Exploring suitable magnetic substances is a prerequisite for practical applications. A family of rare‐earth‐free magnetocaloric materials called Mn30Fe20−xCuxAl50 alloys is identified room‐temperature refrigeration, which are derived from the well‐known MnAl‐based permanent magnets. As expected from experimental and theoretical investigations, all of the Mn30Fe20−xCuxAl50 alloys are crystallized in a stable cubic CsCl‐type crystal structure, revealing a single second‐order type magnetic phase transition (MPT) with tunable MPT temperature. They also exhibit a large reversible MCE and good magnetocaloric performances in a wide temperature range. Crucially, these Mn30Fe20−xCuxAl50 alloys represent a rare case of magnetic materials belonging to a large family that can be fabricated from low‐price, earth‐abundant, and non‐toxic elements. They could provide new choices for practical room‐temperature magnetic refrigeration applications.

Zero Thermal Expansion Effect and Enhanced Magnetocaloric Effect Induced by Fe Vacancies in Fe2Hf0.80Nb0.20 Laves Phase Alloys

“…The magnetic entropy change |Δ S M | illustrated in Figure e,f is calculated from the isofield magnetization curves in Figure c,d based on the Maxwell relation: normalΔ S M false( normalΔ H , T false) = ∫ H 0 H false( ∂ M false( T , H false) ∂ T false) H normald μ 0 H , where we choose μ 0 H 0 = 0 T. The maximal |Δ S M | for the Fe1.95 alloy is 0.50 J/kg K at 170 K with a second peak value of 0.32 J/kg K at 237 K at a magnetic field change of 2 T. For the Fe2.00 alloy, its maximal |Δ S M | is 0.39 J/kg K at 260 K at a magnetic field change of 2 T. The larger magnetization of the Fe1.95 alloy primarily contributes to its 22% larger magnetic entropy change compared to the Fe2.00 alloy. The maximal |Δ S M | of the Fe1.95 alloy is comparable to other Fe-based Laves compounds with a second-order transition, with 0.5 J/kg K in Sc 0.4 Ti 0.6 Fe 2 , with 0.46 J/kg K in Fe 2 Hf 0.85 Ti 0.15 and with 1.3 J/kg K in rare-earth-free Mn 30 Fe 20 Al 50 . It is however smaller than the Fe-based Laves phase materials with a first-order transition, with 1.7 J/kg K in Sc 0.3 Ti 0.7 Fe 2 and 2.3 J/kg K in Fe 2 Hf 0.86 Ta 0.14 .…”

“…The maximal |ΔS M | of the Fe1.95 alloy is comparable to other Fe-based Laves compounds with a second-order transition, with 0.5 J/kg K in Sc 0.4 Ti 0.6 Fe 2 , 32 with 0.46 J/kg K in Fe 2 Hf 0.85 Ti 0.15 12 and with 1.3 J/kg K in rare-earth-free Mn 30 Fe 20 Al 50 . 33 It is however smaller than the Fe-based Laves phase materials with a firstorder transition, with 1.7 J/kg K in Sc 0.3 Ti 0.7 Fe 2 32 and 2.3 J/kg K in Fe 2 Hf 0.86 Ta 0.14 . 8 For the latter, their saturation magnet- izations are ∼2.45 and 2.86 μ B /f.u., respectively, larger than the value of 1.86 μ B /f.u.…”

Magnetic and magnetocaloric effect of Er20Ho20Dy20Cu20Ni20 high-entropy metallic glass

“…[1][2][3][4][5] The magnetocaloric effect (MCE) demonstrated by magnetic materials was considered as a promising alternative to conventional gas compression refrigeration for energy efficient refrigeration technology. [6][7][8] The MCE of magnetic refrigeration materials significantly determines the feasibility of this technology application. La(Fe, Si) 13 -based compounds are considered as promising magnetic refrigeration materials for room temperature refrigeration and have received extensive attention and research, while there are still relatively fewer magnetic refrigeration candidates for the liquid hydrogen temperature region.…”

Magnetic and Magnetocaloric Modifications near Room Temperature in Fe0.6Al0.4 Nanoalloys under Irradiation by Swift Heavy Ions

“…In recent decades, there has been significant interest in the understanding of magnetic and magnetocaloric properties of alloys and compounds upon the basis of transition metals like Fe or Co. − Currently, magnetic refrigeration is widely acknowledged to be an energy-efficient and environmentally friendly commercialized technology. In these studies, there is room for magnetic nanostructured materials, whose properties can differ from those in their bulk counterparts. − Many of these features, intrinsic for magnetic nanomaterials, have great potential for their use in data storage, biomedical, environmental, and heterogeneous catalysis applications.…”