Novel caloric materials by mastering hysteresis: a material science approach

固态制冷在未来可能会取代传统的蒸汽压缩制冷，成为一种完全不同的能源解决方案。最有前景的制冷剂不仅在磁化过程中改变了它们的磁性，而且还改变了它们的晶体结构。高效磁致冷剂的发展是为了最大限度地发挥结构对总熵变的贡献。在这种情况下，滞后是一种不受欢迎的副作用，会导致损失，并阻碍卡路里效应的充分利用。在这个项目中，我们将彻底了解内在和外在磁滞的来源，以便找到一种最小化磁滞的策略。此外，我们将开发优化的、高性能的热量材料，这种材料可以在较小的磁场(μ0H=1T)下提供较大的热量效应，从而大大降低磁性制冷机的成本。我们的战略是利用我们工作组在磁热/高热材料和器件方面的丰富经验，以及我们在材料科学方面的专业知识，包括新颖的合成、先进的表征以及对磁性、微结构和热力学的理解。重点介绍了最有前景的磁性制冷剂，Heusler类Ni-Mn系、La(Fe，Si)13系和Fe2P型MnFeP(Ge，Si)。

Solid-state cooling could be a radically different energy solution substituting conventional vapor compression refrigeration in the future. The most promising refrigerants do not only change their magnetism during magnetization but also their crystal structure. The development of efficient magnetic refrigerants is to maximize the structural contribution to the total entropy change. In this way, hysteresis is an unwanted side-effect that leads to losses and hinders the full use of caloric effects. In this project, we will develop a thorough understanding of the sources of both intrinsic and extrinsic magnetic hysteresis, so that a strategy to minimize hysteresis can be found. Furthermore, we will develop optimized, high-performance caloric materials that deliver a large caloric effect but in a reduced magnetic field (μ0H = 1 T) that would greatly reduce the cost of a magnetic refrigerator. Our strategy is to use the extensive experience of our work-group in magneto/barocaloric materials and devices, and our expertise in materials science, which covers novel synthesis, advanced characterization, and understanding of magnetic properties, microstructure, and thermodynamics. We focus on the most promising magnetic refrigerants, Heusler-type Ni-Mn-based, La(Fe,Si)13-based and Fe2P-type MnFeP(Ge,Si) operating near to ambient conditions.