Solid state materials for magnetic refrigiration: polar intermetallics of main group p-elements and 3d- and 4f-metals as promising magnetocaloric agents

这份拨款申请是为建立一个磁热材料化学研究项目请求资金。研究将集中在设计、合成和表征新的磁热材料，其中铁磁和结构跃迁耦合。这种材料在磁场变化时产生较大的温度响应，可用于制冷和空调。目前尚未充分研究和利用的磁热冷却剂比普通冰箱中使用的蒸汽冷却剂效率更高，机械设计更简单，更环保。这一领域的进展很大程度上取决于新相的发现，这些相具有良好的稳定性、高冷却能力和有用的工作温度。实现良好磁热学性能的关键是将铁磁有序与一阶结构转变耦合起来；与结构转变相关的焓增强了温度响应，提高了材料的冷却效率。在这方面，4f-， 3d-和p-元素的结构灵活的极性金属间相为发现新的磁热相提供了很好的机会。我小组的研究将追求四个不同的方向：沿着Ln(Co1-xBx)5组成线对磁性LnCo5相进行修饰；-磁性尖晶石相的探索；-对三元系（T = Fe， Co和Ni）中稀土富集部分的研究；-研究了mn - co - p和mn - ni - p体系中富过渡金属的部分。

This grant application is requesting funds for establishing a research program in chemistry of magnetocaloric materials. The research will focus on design, synthesis and characterization of new magnetocaloric materials in which ferromagnetic and structural transitions are coupled. Such materials produce a large temperature response with a change in magnetic field and can be used for refrigeration and air-conditioning. Currently understudied and underutilized, magnetocaloric cooling agents offer better efficiency, simpler mechanical design and are more environmentally friendly than vapor cooling agents used in regular refrigerator units. Progress in this area depends strongly on the discovery of new phases with good stability, high cooling capacity and useful operational temperatures. A key to achieving good magnetocaloric properties is to couple a ferromagnetic ordering to a first-order structural transition; the enthalpy associated with the structural transition enhances the temperature response and increases the cooling efficiency of the material. In this respect, structurally flexible polar intermetallic phases of 4f-, 3d- and p-elements present good opportunities for discovery of new magnetocaloric phases. The research in my group will pursue four distinct directions: - modification of the magnetic LnCo5 phases along the Ln(Co1-xBx)5 compositional lines; - exploration of the magnetic spinel phases; - investigation of the rare-earth rich parts of the ternary Ln-T-Sb and Ln-T-Bi systems (T = Fe, Co and Ni); - study of the transition metal rich parts of the Ln-Co-P and Ln-Ni-P systems.