半赫斯勒合金Nb0.8+δCoSb中空位调节有序度的电子显微学研究  

Study of vacancy-induced ordering transformation in half Heusler alloy NbCoSb by electron microscopy

作　　者：南鹏飞 杨丽霞[3] 王玉梅[3] 夏凯阳 朱铁军[4] 葛炳辉 NAN Peng-fei;YANG Li-xia;WANG Yu-mei;XIA Kai-yang;ZHU Tie-jun;GE Bing-hui(Institutes of Physical Science and Information Technology,Anhui University,Anhui Hefei 230601;Key Laboratory of Structure and Functional Regulation of Hybrid Materials(Anhui University),Ministry of Education,Anhui Hefei 230601;Beijing National Laboratory of Condensed Matter Physics,Institute of Physics,Chinese Academy of Sciences,Beijing 100190;School of Materials Science and Engineering,Zhejiang University,Zhejiang Hangzhou 310027,China)

机构地区：[1]安徽大学物质科学与信息技术研究院,安徽合肥230601 [2]安徽大学杂化材料结构与功能调控教育部重点实验室,安徽合肥230601 [3]中国科学院物理研究所北京凝聚态物理国家研究中心,北京100190 [4]浙江大学材料科学与工程学院,浙江杭州310027

出　　处：《电子显微学报》2019年第5期477-482,共6页Journal of Chinese Electron Microscopy Society

基　　金：国家自然科学基金资助项目(No.11874394)

摘　　要：材料的微观结构直接影响材料的物理化学性能,比如,在热电材料里缺陷或者结构的无序会散射声子,从而降低晶格热导,最终提高材料的热电性能。本文主要探究在有缺陷的半赫斯勒合金Nb0.8+δCoSb中,大量空位(16%~20%)存在降低晶格热导率的内在机制;借助电子显微学方法发现在Nb0.8CoSb的样品中存在长程有序和短程有序共存的现象,而在Nb0.84CoSb的样品中短程有序转换为调制结构;借助选区电子衍射技术、中心暗场像技术及球差校正扫描透射电子显微术,分别对上述两种样品的结构进行分析,并对二者之间的相互转换关系进行了讨论。该研究成果为进一步提高热电材料的能量转换效率提供了新的指导。The microstructure of materials directly affects the physical and chemical properties of the materials.For example,defects or structural disorder in the thermoelectric materials will scatter phonons,thus reduce the lattice thermal conductivity and improve the thermoelectric properties of the materials ultimately.In this work,the low lattice thermal conductivity is obtained in the defective half Heusler alloy Nb0.8+δCoSb due to the existence of a large amount of vacancy(16%to 20%).With the help of electron microscopy,we found the co-existence of the vacancy-related short-range order and the crystalline long-range periodic structure in Nb0.8CoSb and long-range order modulated structure in Nb0.84CoSb.The above two structures are analyzed by the selected area electron diffraction technique,central dark field imaging technique and spherical aberration correction scanning transmission electron microscopy.The research results provide important insights for further improving the energy conversion efficiency of thermoelectric materials.

关 键 词：漫散带 调制结构 短程有序 长程有序 晶格热导率 

分 类 号：TB34[一般工业技术—材料科学与工程]