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

该项目是旨在优化和开发新型磁热材料的一揽子计划“掌握磁滞效应的新型热能材料”的一部分。因此，本项目将La(Fe，Si)13，Fe2P和Co-Mn-Ge等已知的磁热系统制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。其目的是确定显示可逆磁/结构转变并具有铁磁性的区域。在下一步中，将使用不同的制备和工艺参数(退火温度和气氛、保持时间和冷却速度)来改变微结构，以调节溶解度、磁滞宽度、磁性能和相变温度。通过添加更多的元素，部分合金间隙进入晶格，材料的性质将通过改变原子间的距离和化学顺序来调整。这些元素将部分地根据在该联盟内密切合作进行的密度泛函理论计算的结果来选择。组合方法允许系统地研究复杂材料系统(三元、四元和四元合金)的结构-性质-关系。这些对复杂系统的系统研究提供了启发式趋势的发展，从而加深了理解。性能优化的样品将提供给财团合作伙伴进行更广泛的实验研究。另一个目标是利用微机械基板直接测量薄膜样品的绝热温度变化。更多关于耐腐蚀性和疲劳的研究将为未来磁制冷应用提供具有优化性能的复合材料的开发。

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.