Gottschall Tino, Gràcia-Condal Adrià, Fries Maximilian, Taubel Andreas, Pfeuffer Lukas, Mañosa Lluís, Planes Antoni, Skokov Konstantin P, Gutfleisch Oliver
Institut für Materialwissenschaft, Technische Universität Darmstadt, Darmstadt, Germany.
Dresden High Magnetic Field Laboratory (HLD-EMFL), Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany.
Nat Mater. 2018 Oct;17(10):929-934. doi: 10.1038/s41563-018-0166-6. Epub 2018 Sep 10.
The giant magnetocaloric effect, in which large thermal changes are induced in a material on the application of a magnetic field, can be used for refrigeration applications, such as the cooling of systems from a small to a relatively large scale. However, commercial uptake is limited. We propose an approach to magnetic cooling that rejects the conventional idea that the hysteresis inherent in magnetostructural phase-change materials must be minimized to maximize the reversible magnetocaloric effect. Instead, we introduce a second stimulus, uniaxial stress, so that we can exploit the hysteresis. This allows us to lock-in the ferromagnetic phase as the magnetizing field is removed, which drastically removes the volume of the magnetic field source and so reduces the amount of expensive Nd-Fe-B permanent magnets needed for a magnetic refrigerator. In addition, the mass ratio between the magnetocaloric material and the permanent magnet can be increased, which allows scaling of the cooling power of a device simply by increasing the refrigerant body. The technical feasibility of this hysteresis-positive approach is demonstrated using Ni-Mn-In Heusler alloys. Our study could lead to an enhanced usage of the giant magnetocaloric effect in commercial applications.
巨磁热效应是指在材料施加磁场时会引起较大的热变化，可用于制冷应用，比如从小规模到相对大规模系统的冷却。然而，其商业应用受到限制。我们提出了一种磁制冷方法，摒弃了传统观念，即磁结构相变材料中固有的磁滞必须最小化才能使可逆磁热效应最大化。相反，我们引入了第二种刺激因素——单轴应力，以便能够利用磁滞。这使我们能够在去除磁化场时锁定铁磁相，从而大幅减少磁场源的体积，进而减少磁制冷机所需的昂贵钕铁硼永磁体的用量。此外，磁热材料与永磁体之间的质量比可以提高，这使得只需增加制冷剂体的量就能扩大设备的制冷功率。利用镍锰铟赫斯勒合金证明了这种磁滞正向方法的技术可行性。我们的研究可能会导致巨磁热效应在商业应用中的使用增加。
