Novel Caloric Materials by Mastering Hysteresis: Combinatorial Development of Magnetocaloric Materials

本项目是“掌握磁滞的新型热材料”一揽子提案的一部分，旨在优化和开发新型磁热材料。因此，在本项目中，已知的磁热系统La(Fe,Si)13， Fe2P和Co-Mn-Ge将被制作成完整的薄膜材料库。自动化的高通量方法将表征这些材料库的化学成分、晶体结构、电阻率和磁性能。目的是识别显示可逆磁/结构转变和铁磁性的区域。在下一步中，制造和加工（退火温度和气氛，停留时间和冷却速度）参数的变化将用于改变微观结构，以调整溶解度，磁滞宽度，磁性能和转变温度。通过在晶格中加入更多的合金元素，可以通过改变原子间距离和化学顺序来调整材料的性质。这些元素的选择将部分基于密度泛函理论计算的结果，这些计算是在联盟内部密切合作中进行的。组合方法允许在结构-性能-关系方面对复杂材料系统（三元，四元和四元合金）进行系统的研究。这些对复杂系统的系统研究提供了启发式趋势的发展，从而有了更深入的理解。具有优化性能的样品将提供给财团合作伙伴进行进一步的实验研究。另一个目标是直接测量薄膜样品的绝热温度变化，通过使用微机械衬底。对耐腐蚀性和疲劳性的进一步研究将为未来磁制冷应用提供具有优化性能的复杂材料的开发。

This project is part of the of the package proposal “Novel Caloric Materials by Mastering Hysteresis”, which aims for the optimization and development of new magnetocaloric materials. Therefore, the known magnetocaloric systems La(Fe,Si)13, Fe2P und Co-Mn-Ge will be fabricated as complete thin film materials libraries in this project. Automated high-throughput methods will characterize these materials libraries regarding chemical composition, crystal structure, electrical resistivity and magnetic properties. The aim is to identify regions, which show a reversible magnetic/structural transformation and are ferromagnetic. In a next step a variation of fabrication and processing (annealing temperature and atmosphere, dwell time and cooling rate) parameters will be used to change the microstructure, in order to adjust solubility, hysteresis width, magnetic properties and transformation temperatures. By the addition of further elements, that partially alloy interstitial into the lattice, the materials properties will be adjusted by changing the inter-atomic distance and chemical order. These elements will be chosen partially on results from density functional theory calculations performed in close collaboration within the consortium. The combinatorial approach allows for a systematic investigation of complex materials systems (ternary, quaternary and quinternary alloys) in regard to the structure-property-relationship. These systematic investigations of complex systems provide the development of heuristic trends and thus a deeper understanding. Samples with optimized properties will be given to consortium partners for extended experimental investigations. A further objective is the direct measurement of adiabatic temperature change in thin film samples by using micro-machined substrates. Additional investigations on corrosion resistance and fatigue will provide the development of complex materials with optimized properties regarding future magnetic refrigeration application.