Ag_(y)In_(3.33-y/3)Se_(5)化合物结构和热电性能  

Structure and thermoelectric performance of Ag_(y)In_(3.33-y/3)Se_(5) compounds

作　　者：訾鹏 白辉 汪聪 武煜天 任培安 陶奇睿 吴劲松 苏贤礼[1] 唐新峰[1] Zi Peng;Bai Hui;Wang Cong;Wu Yu-Tian;Ren Pei-An;Tao Qi-Rui;Wu Jin-Song;Su Xian-Li;Tang Xin-Feng(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,材料复合新技术国家重点实验室,武汉430070 [2]武汉理工大学纳微结构研究中心,武汉430070

出　　处：《物理学报》2022年第11期314-325,共12页Acta Physica Sinica

基　　金：国家重点研发计划(批准号:2018YFB0703600);国家自然科学基金(批准号:52122108,51972256)资助的课题.

摘　　要：本文使用静态扩散法结合常规X射线粉末衍射和电子探针技术,在Ag-In-Se体系中发现了Ag_(y)In_(3.33-y/3)Se_(5)新化合物.其结构属于三方晶系,空间群为P3m1,是二维层状结构,单层晶胞由9个原子量子层按照Se1-In1-Se2-In2-Se3-Ag/In3-Se4-In4-Se5顺序排布构成,层间由弱范德瓦耳斯力结合.烧结的块体样品表现出强烈的取向性,在平行压力方向上具有极低的晶格热导率(在873 K为0.15 W·m^(-1)·K^(-1)).这种本征低的晶格热导率主要源于材料的低声速和低频光学支声子与声学支声子强耦合作用.Ag_(y)In_(3.33-y/3)Se_(5)样品表现为n型传导,室温下电导率约为4×10^(4)S·m^(-1),Seebeck系数约为-80μV·K^(-1),样品在宽温度范围内均表现出较好的电传输性能,在450—800 K范围内的功率因子为5μW·cm^(-1)·K^(-2)左右.由于在平行压力方向上低的晶格热导率,最终Ag_(0.407)In_(3.198)Se_(5)样品在873 K达到最大热电优值ZT为1.01,在300—850 K的平均ZT为0.45.该化合物的发现,扩充了铜属硫基化合物体系的n型材料,为铜属硫基化合物体系的应用奠定了重要基础.In this study,we find new Ag_(y)In_(3.33-y/3)Se_(5) compounds in Ag-In-Se system by static diffusion method combined with common X-ray diffraction and backscattering electron analysis.The crystal structure belongs to the trilateral system with the P3m1 space group,which features a two-dimensional layered structure.The unit cell is composed of 9-atom quantum layers arranged in the sequence of Se1-In1-Se2-In2-Se3-Ag/In3-Se4-In4-Se5,and in-between these layers are bonded by the weak van der Waals force.The sintered bulk samples show highly anisotropic transport properties and have an ultra-low lattice thermal conductivity along the direction parallel to sintering pressure about 0.15 W·m^(-1)·K^(-1) at 873 K.The intrinsically ultra-low lattice thermal conductivity mainly comes from low phonon velocity and the strong coupling between low frequency optical phonon and acoustic phonons.The Ag_(y)In_(3.33-y/3)Se_(5) compounds behave as an n-type conduction.The electrical conductivity is 4×10^(4)S·m^(-1) and the Seebeck coefficient is-80μV·K-1 at room temperature.Therefore,Ag_(y)In_(3.33-y/3)Se_(5) compounds show high electrical transport properties in a wide temperature range,and the power factor is around 5μW·cm^(-1)·K^(-2) in a range of 450-800 K.Owing to the ultra-low lattice thermal conductivity along the direction parallel to sintering pressure,Ag_(0.407)In_(3.198)Se_(5) reaches a maximum ZT of 1.01 at 873 K and an average ZT of 0.45 at 300-850 K.The discovery of Ag_(y)In_(3.33-y/3)Se_(5) expands the n-type copper based chalcogenide and lays an important foundation for the application of copper based chalcogenide.

关 键 词：Ag-In-Se基化合物 二维层状结构 超低晶格热导率 热电性能 

分 类 号：O611.6[理学—无机化学]