n型Bi_(2-x)Sb_(x)Te_(3-y)Se_(y)基化合物的缺陷结构调控与电热输运性能  

Defect structure regulation and thermoelectric transfer performance in n-type Bi_(2-x)Sb_(x)Te_(3-y)Se_(y)-based compounds

作　　者：李睿英 罗婷婷[1,2] 李貌 陈硕 鄢永高[1,2] 吴劲松 苏贤礼[1,2] 张清杰 唐新峰[1,2] Li Rui-Ying;Luo Ting-Ting;Li Mao;Chen Shuo;Yan Yong-Gao;Wu Jin-Song;Su Xian-Li;Zhang Qing-Jie;Tang Xin-Feng(Longzhong Laboratory in Hubei Province,Xiangyang Demonstration Zone of Wuhan University of Technology,Xiangyang 441000,China;State Key Laboratory of Advanced Technology for Materials Synthesis and Processing,Wuhan University of Technology,Wuhan 430070,China;Nanostructure Research Center,Wuhan University of Technology,Wuhan 430070,China)

机构地区：[1]武汉理工大学襄阳示范区,湖北隆中实验室,襄阳441000 [2]武汉理工大学,材料复合新技术国家重点实验室,武汉430070 [3]武汉理工大学纳微结构研究中心,武汉430070

出　　处：《物理学报》2024年第9期244-253,共10页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:52122108);国家重点研发计划(批准号:2018YFB0703600);湖北隆中实验室自主创新项目(批准号:2022ZZ-07)资助的课题

摘　　要：Bi_(2)Te_(3)基化合物是目前室温附近性能最好的热电材料,但其存在着大量复杂的缺陷结构,缺陷工程是调控材料热电性能的核心手段,因此理解和有效地调控缺陷形态和浓度是获得高性能Bi_(2)Te_(3)基热电材料的关键.本文系统地研究了四元n型Bi_(2-x)Sb_(x)Te_(3-y)Se_(y)基化合物的缺陷演化过程及其对热电输运性能的影响规律.Sb和Se的固溶引入的带电伴生结构缺陷使得材料的载流子浓度发生了巨大变化,在Bi_(2-x)Sb_(x)Te_(2.994)Cl_(0.006)样品中,Sb的固溶降低了反位缺陷Sb_(Te)_(2)形成能,诱导产生了反位缺陷Sb_(Te)_(2),使得少数载流子空穴浓度从2.09×10^(16)cm^(-3)增加至3.99×10^(17)cm^(-3),严重劣化了电性能.在Bi_(1.8)Sb_(0.2)Te_(2.994-y)Se_(y)Cl_(0.006)样品中,Se的固溶使得Se(Te)_(2)+SbBi的缺陷形成能更低,抑制了反位缺陷Sb_(Te)_(2)的产生,Bi_(1.8)Sb_(0.2)Te_(2.694)Se_(0.30)Cl_(0.006)样品的少数载流子空穴浓度降至1.49×10^(16)cm^(-3),消除了其对材料热电性能的劣化效果,显著地提升了材料的功率因子,室温下达到4.49 mW/(m·K^(2)).结合Sb和Se固溶增强合金化散射降低材料的热导率,Bi_(1.8)Sb_(0.2)Te_(2.844)Se_(0.15)Cl_(0.006)样品在室温下获得最大ZT值为0.98.该研究为调控具有复杂成分的Bi_(2)Te_(3)基材料的点缺陷、载流子浓度和热电性能提供了重要的指导.Bi_(2)Te_(3)-based compounds are thermoelectric materials with the best performance near room temperature.The existence of a large number of complex defects makes defect engineering a core stratagem for adjusting and improving the thermoelectric performance.Therefore,understanding and effectively controlling the existence form and concentration of defects is crucial for achieving high-thermoelectric performance in Bi_(2)Te_(3)-based alloy.Herein,a series of Cl doped n-type quaternary Bi_(2-x)Sb_(x)Te_(3-y)Se_(y)compounds is synthesized by the zone-melting method.The correlation between defect evolution process and thermoelectric performance is systematically investigated by first-principles calculation and experiments.Alloying Sb on Bi site and Se on Te site induce charged structural defects,leading to a significant change in the carrier concentration.For Bi_(2-x)Sb_(x)Te_(2.994)Cl_(0.006)compounds,alloying Sb on Bi site reduces the formation energy of the Sb_(Te)_(2) antisite defect,which generates the antisite defect Sb_(Te)_(2) and accompanied with the increase of the minority carrier concentration from 2.09×10^(16)to 3.99×10^(17)cm^(-3).The increase of the minority carrier severely deteriorates the electrical transport properties.In contrast,alloying Se in the Bi_(1.8)Sb_(0.2)Te_(2.994-y)Se_(y)Cl_(0.006)compound significantly lowers the formation energy of the complex defect SeTe+SbBi,which becomes more energetically favorable and suppresses the formation of the antisite defect Sb_(Te)_(2).As a result,the concentration of minority carriers decreases to 1.46×10^(16)cm^(-3).This eliminates the deterioration effect of the minority carrier on the electrical transport properties of the material and greatly improves the power factor.A maximum power factor of 4.49 mW/(m·K^(2))is achieved for Bi_(1.8)Sb_(0.2)Te_(2.944)Se_(0.05)Cl_(0.006)compound at room temperature.By reducing thermal conductivity through intensifying the phonon scattering via alloying Sb and Se,the maximum ZT value of 0.98 is attained for Bi_(1.

关 键 词：Bi2Te3基化合物 缺陷工程 热电性能 

分 类 号：TB34[一般工业技术—材料科学与工程]