Abstract
First-order isostructural magnetoelastic transition with large magnetization difference and controllable thermal hysteresis are highly desirable in the development of high-performance magnetocaloric materials used for energy-efficient and environmental-friendly magnetic refrigeration. Here, we demonstrate large magnetocaloric effect covering the temperature range from 325 K to 245 K in Laves phase Hf1−xTaxFe2 (x = 0.13, 0.14, 0.15, 0.16) alloys undergoing the magnetoelastic transition from antiferromagnetic (AFM) state to ferromagnetic (FM) state on decreasing the temperature. It is shown that with the increase of Ta content, the nature of AFM to FM transition is gradually changed from second-order to first-order. Based on the direct measurements, large reversible adiabatic temperature change (ΔTad) values of 2.7 K and 3.4 K have been achieved under a low magnetic field change of 1.5 T in the Hf0.85Ta0.15Fe2 and Hf0.84Ta0.16Fe2 alloys with the first-order magnetoelastic transition, respectively. Such remarkable magnetocaloric response is attributed to the rather low thermal hysteresis upon the transition as these two alloys are close to intermediate composition point of second-order transition converting to first-order transition.
Highlights
Magnetic refrigeration, as an alternative cooling technology with the promises of high-efficiency and environment-friendly, has been recognized as a competitive substitute to replace the conventional gas-compression based refrigeration technology
Magnetic refrigeration is designed on the basis of magnetocaloric effect (MCE) [1], which is an intrinsic magneto-thermodynamic property of magnetic materials, using the isothermal magnetic entropy change (∆SM ) or the adiabatic temperature change (∆Tad ) on exposure to a magnetic field as the performance index
In the vicinity of the intermediate composition point of second-order transition converting to first-order transition, large reversible ∆Tad values of 2.7 K and 3.4 K have been demonstrated under a low magnetic field change of 1.5 T in the Hf0.85 Ta0.15 Fe2 alloy and Hf0.84 Ta0.16 Fe2 alloy, respectively, due to the rather low thermal hysteresis upon the first-order magnetic transition
Summary
As an alternative cooling technology with the promises of high-efficiency and environment-friendly, has been recognized as a competitive substitute to replace the conventional gas-compression based refrigeration technology. An interesting system exhibiting the magnetoelastic transition is the itinerant-electron pseudobinary Hf1−x Tax Fe2 alloys with hexagonal (MgZn2 -type) Laves phase structure, experiencing the iso-structural transition from antiferromagnetic (AFM) state to ferromagnetic (FM) state on decreasing the temperature [18,19,20,21]. In the vicinity of the intermediate composition point of second-order transition converting to first-order transition, large reversible ∆Tad values of 2.7 K and 3.4 K have been demonstrated under a low magnetic field change of 1.5 T in the Hf0.85 Ta0.15 Fe2 alloy and Hf0.84 Ta0.16 Fe2 alloy, respectively, due to the rather low thermal hysteresis upon the first-order magnetic transition
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