Synthesis, structure and properties of responsive solid-state materials

响应材料在恒定或可变的施加力或场下表现出独特的物理响应。这种物理响应与固态相的出色机械性能相结合，产生了在工业和消费者层面都有应用的功能材料。该研究将集中在响应固态材料的两个领域：磁热相和热电相。当磁场变化时，磁热材料通过改变它们的温度来响应，并且可以用于磁冷却，这比传统的蒸汽循环制冷提供更好的效率。热电材料在经受温度梯度时产生电压，或者在电流通过它们时执行冷却/加热。目前，热电材料用于深空使命、远程气象和导航系统的发电，以及电子设备和汽车座椅的冷却。由于一半的能量以废热的形式损失，研究工作开始集中在通过热电发电机回收这些能量，特别是在汽车和烤箱中。该研究的短期目标是发现和表征新型高性能热电和磁热材料。从长远来看，我们的目标是更深入地了解这些类型材料的组成-结构-性能关系，并将所获得的知识用于新材料的快速和有针对性的设计。在热电材料中，我们将重点关注通式为Lnm（Sb，Bi）nOm的镧系元素（Ln）锑化物和铋化物的低氧化物的合成。这些相可以被归类为“电子晶体声子玻璃”材料，因为它们是良好的电导体，而它们的热导率非常低，接近于非晶态材料。一些Lnm（Sb，Bi）nOm材料显示出新颖的电荷传输机制，我们希望使用这些机制来优化它们的热电性能。本课题组率先开展了Lnm（Sb，Bi）nOm低氧化物的研究，并希望在这一领域保持领先地位。在磁热领域，我们将追求有针对性的合成新的极性金属间化合物材料，其中铁磁有序耦合到室温或接近室温的结构转变。我们提出利用价电子浓度和尺寸效应来调控新型磁热材料的结构和磁性。这些方法是我们团队的先驱，我们将应用它们来制备新型高性能相。

Responsive materials exhibit unique physical responses under constant or variable applied forces or fields. Combination of such physical responses with outstanding mechanical properties of solid-state phases yields functional materials that find applications both at the industrial and consumer levels. The research will focus on two areas of responsive solid-state materials: magnetocaloric and thermoelectric phases. Magnetocaloric materials respond by changing their temperature when the magnetic field is varied and can be used for magnetic cooling, which offers better efficiency than conventional vapour-cycle refrigeration. Thermoelectric materials generate voltage when subject to a temperature gradient or perform cooling/heating when current is passed through them. Currently, thermoelectric materials are used for power generation in deep-space mission, remote weather and navigation systems and for cooling in electronic devices and car seats. And since half of the energy is lost as a waste heat, research efforts start to focus on recovering some of this energy, especially in cars and ovens, through thermoelectric generators. The short term goals of the proposed research will be discovery and characterization of novel, high-performance thermoelectric and magnetocaloric materials. In the long run, we aim to develop a deeper understanding of the composition-structure-property relationship in these types of materials, and to use the obtained knowledge for the rapid and targeted design of new materials. Among the thermoelectric materials, we will focus on the synthesis of lanthanoid (Ln) antimonide and bismuthide suboxides with the general formula Lnm(Sb,Bi)nOm. These phases may be classified as "electron-crystal phonon-glass" materials, as they are good electrical conductors, while their thermal conductivity is very low and is approaching that of amorphous materials. Some of the Lnm(Sb,Bi)nOm materials display novel charge transport mechanisms and we want to use these mechanisms to optimize their thermoelectric properties. The research on the Lnm(Sb,Bi)nOm suboxides was initiated in our group and we would like to maintain our leading role in this area. In the magnetocaloric field, we will pursue targeted synthesis of new polar intermetallic materials, in which a ferromagnetic ordering is coupled to a structural transition at or near room temperature. We proposed to utilize the valence electron concentration and size effects to tune structural and magnetic properties of new magnetocaloric materials. These approaches were pioneered in our group and we will apply them to prepare novel high-performance phases.