(浙江大学 材料科学与工程系 硅材料国家重点实验室，杭州 310027)
摘 要: 采用缓慢冷却和液氮淬火两种真空熔炼工艺得到Bi2Te2.4Se0.6合金铸锭，再将铸锭研磨后热压烧结制备N型多晶样品。采用XRD、FESEM、激光热导仪及电学性能测试仪对样品的物相组成、断面形貌和热电性能进行分析和研究。结果表明：制备的多晶样品为单相；振动研磨得到的粉末热压后保留大量的微米级(1~5 μm)颗粒。结合取向因子的计算结果可以推断，样品中无明显的晶粒择优取向；采用液氮淬火制备的样品由于晶粒细化的影响，其热导率显著降低，热电性能得到改善。在300~500 K温度范围内，液氮淬火试样BTSRS-OM-HP具有最大的功率因子和最低的晶格热导率；室温至500 K范围内，样品的晶格热导率保持在0.42~0.51 W/(m∙K)之间，在468 K时，获得最大ZT值0.87。
关键字: Bi2Te2.4Se0.6；液氮淬火；热电性能；热电材料
N-type Bi2Te2.4Se0.6 bulk alloys
（State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering,
Zhejiang University, Hangzhou 310027, China）
Abstract:The Bi2Te2.4Se0.6 polycrystalline samples were prepared by smashing Bi2Te2.4Se0.6 alloys combined with a subsequent hot pressing sintering technique. The thermoelectric properties were measured at 300−500 K. XRD analysis shows that the single phase Bi2Te3 is obtained. The FESEM results show that the fracture morphologies of samples show that the particle size of hot pressed samples remains micrometer scale ranging from 1 to 5 μm. The crystal growth with disordered crystal orientation according to the values of orientation factor F. The measurements of thermoelectric properties show that an improvement in thermoelectric figure of merit is obtained caused by a remarkable decrease in thermal conductivity due to strong phonon scattering induced by a fine microstructure of the sample BTSRS-OM-HP prepared by rapid solidification combined with hot pressing process, whose lattice thermal conductivity ranges within 0.42~0.51 W/(m∙K) from room temperature to 500 K, and the maximum dimensionless merit figure ZT value of 0.87 is obtained at 468 K.
Key words: Bi2Te2.4Se0.6; liquid nitrogen quenching; thermoelectric properties; thermoelectric materials
