IFW Dresden, Institute for Metallic Materials, PO Box 270116, D-01171 Dresden, Germany.
Nat Mater. 2012 Jul;11(7):620-6. doi: 10.1038/nmat3334.
Magnetic cooling could be a radically different energy solution substituting conventional vapour compression refrigeration in the future. For the largest cooling effects of most potential refrigerants we need to fully exploit the different degrees of freedom such as magnetism and crystal structure. We report now for Heusler-type Ni–Mn–In–(Co) magnetic shape-memory alloys, the adiabatic temperature change ΔT(ad) = −3.6 to −6.2 K under a moderate field of 2 T. Here it is the structural transition that plays the dominant role towards the net cooling effect. A phenomenological model is established that reveals the parameters essential for such a large ΔT(ad). We also demonstrate that obstacles to the application of Heusler alloys, namely the usually large hysteresis and limited operating temperature window, can be overcome by using the multi-response to different external stimuli and/or fine-tuning the lattice parameters, and by stacking a series of alloys with tailored magnetostructural transitions.
磁性冷却可能是一种截然不同的能源解决方案，未来有望替代传统的蒸气压缩制冷。对于大多数潜在制冷剂的最大冷却效果，我们需要充分利用不同的自由度，如磁性和晶体结构。我们现在报告了 Heusler 型 Ni-Mn-In-(Co) 磁性形状记忆合金在 2 T 适度磁场下的绝热温度变化 ΔT(ad) = -3.6 至 -6.2 K。在这里，结构转变对净冷却效果起着主导作用。建立了一个唯象模型，揭示了实现如此大的 ΔT(ad) 的关键参数。我们还证明，Heusler 合金应用的障碍，即通常较大的磁滞和有限的工作温度窗口，可以通过利用对不同外部刺激的多响应和/或微调晶格参数，以及通过堆叠一系列具有定制磁结构转变的合金来克服。
