(浙江大學(xué) 材料科學(xué)與工程系 硅材料國家重點(diǎn)實驗室，杭州 310027)
摘 要: 采用緩慢冷卻和液氮淬火兩種真空熔煉工藝得到Bi2Te2.4Se0.6合金鑄錠，再將鑄錠研磨后熱壓燒結(jié)制備N型多晶樣品。采用XRD、FESEM、激光熱導(dǎo)儀及電學(xué)性能測試儀對樣品的物相組成、斷面形貌和熱電性能進(jìn)行分析和研究。結(jié)果表明：制備的多晶樣品為單相；振動研磨得到的粉末熱壓后保留大量的微米級(1~5 μm)顆粒。結(jié)合取向因子的計算結(jié)果可以推斷，樣品中無明顯的晶粒擇優(yōu)取向；采用液氮淬火制備的樣品由于晶粒細(xì)化的影響，其熱導(dǎo)率顯著降低，熱電性能得到改善。在300~500 K溫度范圍內(nèi)，液氮淬火試樣BTSRS-OM-HP具有最大的功率因子和最低的晶格熱導(dǎo)率；室溫至500 K范圍內(nèi)，樣品的晶格熱導(dǎo)率保持在0.42~0.51 W/(m∙K)之間，在468 K時，獲得最大ZT值0.87。
關(guān)鍵字: Bi2Te2.4Se0.6；液氮淬火；熱電性能；熱電材料
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
