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The world's growing hunger for artificial cold, on the one hand, and the ever more stringent climate targets, on the other, pose an enormous challenge to mankind. Novel, efficient, and environmentally friendly refrigeration technologies based on solid-state refrigerants can offer a way out of the problems arising from climate-damaging substances used in conventional vapor-compressors. Multicaloric materials stand out because of their large temperature changes, which can be induced by the application of different external stimuli such as a magnetic, electric, or a mechanical field. Despite the high potential for applications and the interesting physics of this group of materials, few studies focus on their investigation by direct methods. In this paper, we report on the advanced characterization of all relevant physical quantities that determine the multicaloric effect of a Ni-Mn-In Heusler compound. We have used a purpose-designed calorimeter to determine the isothermal entropy and adiabatic temperature changes resulting from the combined action of magnetic field and uniaxial stress on this metamagnetic shape-memory alloy. From these results, we can conclude that the multicaloric response of this alloy by appropriate changes of uniaxial stress and magnetic field largely outperforms the caloric response of the alloy when subjected to only a single stimulus. We anticipate that our findings can be applied to other multicaloric materials, thus inspiring the development of refrigeration devices based on the multicaloric effect. [ABSTRACT FROM AUTHOR]

We study the giant elastocaloric effect in a Cu–Zn–Al shape‐memory alloy by means of simultaneous calorimetry and dilatometry measurements under applied uniaxial compression which have been carried out with a bespoke experimental setup. The output data allow a unique quasidirect and indirect characterization of the thermal response that provides accurate ΔS and ΔT values. We report a large thermal response of |ΔS| = 22 J K kg−1, |ΔT| = 12.3 K, and RC = 325 K kg−1 driven by moderate uniaxial compression changes of 32.2 MPa, which is comparable with the performance of the best magnetocaloric materials. In view of the hysteresis effects, the thermal response is predicted to exhibit reversible values for |Δσ| = 32 MPa. [ABSTRACT FROM AUTHOR]

We report on the adiabatic temperature changes (ΔT) associated with the magnetocaloric and barocaloric effects in a Fe49Rh51 alloy. For the magnetocaloric effect, data derived from entropy curves are compared to direct thermometry measurements. The agreement between the two sets of data provides support to the estimation of ΔT for the barocaloric effect, which are indirectly determined from entropy curves. Large ΔT values are obtained at relatively low values of magnetic field (2 T) and hydrostatic pressure (2.5 kbar). It is also shown that both magnetocaloric and barocaloric effects exhibit good reproducibility upon magnetic field and hydrostatic pressure cycling, over a considerable temperature range. [ABSTRACT FROM AUTHOR]

We report on the adiabatic temperature changes (ΔT) associated with the magnetocaloric and barocaloric effects in a Fe49Rh51 alloy. For the magnetocaloric effect, data derived from entropy curves are compared to direct thermometry measurements. The agreement between the two sets of data provides support to the estimation of ΔT for the barocaloric effect, which are indirectly determined from entropy curves. Large ΔT values are obtained at relatively low values of magnetic field (2 T) and hydrostatic pressure (2.5 kbar). It is also shown that both magnetocaloric and barocaloric effects exhibit good reproducibility upon magnetic field and hydrostatic pressure cycling, over a considerable temperature range. [ABSTRACT FROM AUTHOR]

A giant barocaloric effect (BCE) in a molecular material Fe 3 (bntrz) 6 (tcnset) 6 (FBT) is reported, where bntrz = 4-(benzyl)-1,2,4-triazole and tcnset = 1,1,3,3-tetracyano-2-thioethylepropenide. The crystal structure of FBT contains a trinuclear transition metal complex that undergoes an abrupt spin-state switching between the state in which all three Fe II centers are in the high-spin (S = 2) electronic configuration and the state in which all of them are in the low-spin (S = 0) configuration. Despite the strongly cooperative nature of the spin transition, it proceeds with a negligible hysteresis and a large volumetric change, suggesting that FBT should be a good candidate for producing a large BCE. Powder X-ray diffraction and calorimetry reveal that the material is highly susceptible to applied pressure, as the transition temperature spans the range from 318 at ambient pressure to 383 K at 2.6 kbar. Despite the large shift in the spin-transition temperature, its nonhysteretic character is maintained under applied pressure. Such behavior leads to a remarkably large and reversible BCE, characterized by an isothermal entropy change of 120 J kg -1 K -1 and an adiabatic temperature change of 35 K, which are among the highest reversible values reported for any caloric material thus far., (© 2021 Wiley-VCH GmbH.)