LaB6-基稀土六硼化物纳米结构的可控生长及性能

稀土六硼化物具有高熔点、高硬度、高化学稳定性、低逸出功、一定温度内的零膨胀系数等优点。用它制备的场发射器件性能稳定，使用寿命长，因此，被认为是性能优异的场电子发射阴极材料。最近实验和理论给出确切证据支持SmB6是第一种真正意义上的三维拓扑绝缘体。本申请项目拟用Ag, Pt，Co，Fe等为催化剂、稀土粉末为稀土源、多孔阳极氧化铝(AAO)或沸石为模板、BCl3为B源，探索稀土六硼化物体系(RB6)中稀土R位用其它稀土元素或碱金属元素(如 Ca, Sr, Ba等)进行掺杂的两个系列纳米线和纳米管可控生长的成相规律；用X射线衍射、电子显微镜、热分析、霍尔和场发射性能测试以及理论分析等方法重点研究微结构、结构和物性以及组分、结构、性能的相互关系，并对结构的稳定性和变化规律进行深入研究，阐明微结构的变化对RB6体系场发射性能及SmB6中拓扑绝缘体表面态等性能影响的机制。

Rare earth hexaborides RB6 have been used as the best cathode electron emission sources due to their high melting point, high hardness. high chemical stability, low work function and zero thermal expansion coefficient within a certain temperature range. Recently, the data from the calculation and experimentation reveal that SmB6 is the first true three-dimensional topological insulator with an insulating bulk and a metallic surface. In this project, the rare-earth hexaborides nanotubes and nanowires doping in R site with other rare-earth elements R or alkali elements (Ca, Sr, Ba etc) will be prepared by using the reaction of rare-earth metal powders with BCl3 gas, where Ag, Pt, Co, Fe etc. will be used as the catalyst and anodic aluminum oxide (AAO) or zeolite as the templet. The rules of the growing rare-earth hexaborides nanotubes and nanowires in a controlled manner will be studied. The relationship between preparing conditions and images as well as the microstructure will be studied. The microstructure, phase relationship, as well as the relations among the structure, composition, and the properties will be characterized using x-ray diffraction, TEM, SEM, DSC, Hall-effect and field emission measurement. The effects of images and microstructure on the the emission properties and the surface state of the SmB6 topological insulator will be discussed.