Novel caloric materials by mastering hysteresis: a material science approach

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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.