Barocaloric and magnetocaloric effects inFe49Rh51

Abstract

We report on calorimetry under applied hydrostatic pressure and magnetic field at the antiferromagnetic (AFM)-ferromagnetic (FM) transition of Fe 49 Rh 51 . Results demonstrate the existence of a giant barocaloric effect in this alloy, a new functional property that adds to the magnetocaloric and elastocaloric effects previously reported for this alloy. All caloric effects originate from the AFM/FM transition which encompasses changes in volume, magnetization and entropy.The strong sensitivity of the transition temperatures to both hydrostatic pressure and magnetic field confers to this alloy outstanding values for the barocaloric and magnetocaloric strengths (|∆S|/∆p ∼ 12 J kg −1 K −1 kbar −1 and |∆S|/µ 0 ∆H ∼ 12 J kg −1 K −1 T −1 ). Both barocaloric and magnetocaloric effects have been found to be reproducible upon pressure and magnetic field cycling. Such a good reproducibility and the large caloric strengths make Fe-Rh alloys particularly appealing for solid-state cooling technologies at weak external stimuli.

Reversible adiabatic temperature changes at the magnetocaloric and barocaloric effects in Fe49Rh51

“…Present sample has the same nominal composition than the sample studied in ref. [10] and transition temperatures are coincident within experimental error. However, conventional DSC measurements render a value for the transition entropy change (∆S t = 11.1 J/kg K) that is slightly lower than that of the previously studied sample (∆S t = 12.5 J/kg K).…”

“…On the one hand, it has been evidenced that in accurately prepared samples, the entropy change associated with the magnetocaloric effect exhibits good reproducibility upon magnetic field cycling [10,12]. It has also recently been shown [10] that in addition to the afore mentioned magnetocaloric and elastocaloric effects, the alloy also exhibits a giant barocaloric effect, associated with the application of hydrostatic pressure.…”

“…On the one hand, it has been evidenced that in accurately prepared samples, the entropy change associated with the magnetocaloric effect exhibits good reproducibility upon magnetic field cycling [10,12]. It has also recently been shown [10] that in addition to the afore mentioned magnetocaloric and elastocaloric effects, the alloy also exhibits a giant barocaloric effect, associated with the application of hydrostatic pressure. The strong sensitivity of the transition temperature to the external fields (magnetic and mechanical) confer to this alloy outstanding magnetocaloric and barocaloric strengths in comparison to other materials [13] which make it particularly interesting for cooling applications at low fields.…”

“…In addition, the reversibility of the effect under a cyclic variation of the external field must also be considered [16][17][18][19][20]. In a previous work [10], we reported on the isothermal entropy change of Fe 49 Rh 51 . We provided the first evidence of the existence of giant barocaloric effects and we proved that the values for the entropy change in both magnetocaloric and barocaloric effects were reproducible upon field cycling.…”

Inverse barocaloric effects in ferroelectric BaTiO3 ceramics

“…Our observation of reversible BC effects near the Curie temperature of BTO should inspire studies of BC effects in a wide range of ferroelectric materials. This should expand the range of BC materials beyond ammonium sulphate 28 and a small number of magnetic materials, [44][45][46][47][48] allowing caloric properties to be exploited in cooling devices without the electrical breakdown that limits EC effects.…”