title: Multiple Converged Conduction Bands in K2Bi8Se13: A Promising Thermoelectric Material with Extremely Low Thermal Conductivity.
abstract: We report that K2Bi8Se13exhibits multiple conduction bands that lie close in energy and can be activated through doping, leading to a highly enhanced Seebeck coefficient and a high power factor with elevated temperature. Meanwhile, the large unit cell, complex low symmetry crystal structure, and nondirectional bonding lead to the very low lattice thermal conductivity of K2Bi8Se13, ranging between 0.42 and 0.20 W m-1K-1in the temperature interval 300-873 K. Experimentally, we further support the low thermal conductivity of K2Bi8Se13using phonon velocity measurements; the results show a low average phonon velocity (1605 ms-1), small Young's modulus (37.1 GPa), large Grüneisen parameter (1.71), and low Debye temperature (154 K). A detailed investigation of the microstructure and defects was carried out using electron diffraction and transmission microscopy which reveal the presence of a K2.5Bi8.5Se14minor phase intergrown along the side of the K2Bi8Se13phase. The combination of enhanced power factor and low thermal conductivity results in a high ZT value of ∼1.3 at 873 K in electron doped K2Bi8Se13material.
authors.affiliation: School of Materials Science and Engineering, Beihang University , Beijing 100191, China.
authors.forename: Yanling
authors.initials: Y
authors.lastname: Pei
authors.affiliation: School of Materials Science and Engineering, Beihang University , Beijing 100191, China.
authors.forename: Cheng
authors.initials: C
authors.lastname: Chang
authors.affiliation: Department of Physics, South University of Science and Technology of China , Shenzhen 518055, China.|Shenzhen Key Laboratory of Thermoelectric Materials , Shenzhen 518055, China.
authors.forename: Zhe
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Department of Physics, South University of Science and Technology of China , Shenzhen 518055, China.|Shenzhen Key Laboratory of Thermoelectric Materials , Shenzhen 518055, China.
authors.forename: Meijie
authors.initials: M
authors.lastname: Yin
authors.affiliation: Department of Physics, South University of Science and Technology of China , Shenzhen 518055, China.|Shenzhen Key Laboratory of Thermoelectric Materials , Shenzhen 518055, China.
authors.forename: Minghui
authors.initials: M
authors.lastname: Wu
authors.affiliation: Department of Chemistry, Northwestern University , Evanston, Illinois 60208, United States.
authors.forename: Gangjian
authors.identifier: 0000-0002-9087-4048
authors.initials: G
authors.lastname: Tan
authors.affiliation: Department of Physics, South University of Science and Technology of China , Shenzhen 518055, China.|Shenzhen Key Laboratory of Thermoelectric Materials , Shenzhen 518055, China.|Department of Materials Science and Engineering, National University of Singapore , 7 Engineering Drive 1, Singapore 117575, Singapore.
authors.forename: Haijun
authors.initials: H
authors.lastname: Wu
authors.affiliation: Department of Physics, South University of Science and Technology of China , Shenzhen 518055, China.|Shenzhen Key Laboratory of Thermoelectric Materials , Shenzhen 518055, China.
authors.forename: Yuexing
authors.initials: Y
authors.lastname: Chen
authors.affiliation: School of Materials Science and Engineering, Beihang University , Beijing 100191, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Zheng
authors.affiliation: School of Materials Science and Engineering, Beihang University , Beijing 100191, China.
authors.forename: Shengkai
authors.initials: S
authors.lastname: Gong
authors.affiliation: State Key Laboratory of Silicon Materials and School of Materials Science and Engineering, Zhejiang University , Hangzhou 310027, China.
authors.forename: Tiejun
authors.initials: T
authors.lastname: Zhu
authors.affiliation: State Key Laboratory of Silicon Materials and School of Materials Science and Engineering, Zhejiang University , Hangzhou 310027, China.
authors.forename: Xinbing
authors.initials: X
authors.lastname: Zhao
authors.affiliation: Department of Physics, South University of Science and Technology of China , Shenzhen 518055, China.|Shenzhen Key Laboratory of Thermoelectric Materials , Shenzhen 518055, China.
authors.forename: Li
authors.initials: L
authors.lastname: Huang
authors.affiliation: Department of Physics, South University of Science and Technology of China , Shenzhen 518055, China.|Shenzhen Key Laboratory of Thermoelectric Materials , Shenzhen 518055, China.
authors.forename: Jiaqing
authors.initials: J
authors.lastname: He
authors.affiliation: Department of Chemistry, Northwestern University , Evanston, Illinois 60208, United States.
authors.forename: Mercouri G
authors.initials: MG
authors.lastname: Kanatzidis
authors.affiliation: School of Materials Science and Engineering, Beihang University , Beijing 100191, China.
authors.forename: Li-Dong
authors.identifier: 0000-0003-1247-4345
authors.initials: LD
authors.lastname: Zhao