Bi₂(Te_1-xSe_x)₃复合热电材料的制备及特性研究

Preparation and Properties of Bi₂(Te_1-xSe_x)₃ Composite Thermoelectric Materials

摘要: 本文利用模具热压烧结法，通过在Bi₂Te₃基体中掺杂少量的Bi₂Se₃，制备出了Bi₂(Te_1−xSe_x)₃固溶体合金复合热电材料。利用XRD、SEM及热电特性实验分析设备，对不同样品的晶体结构、表面形貌、组成成份及热电特性进行了比较分析。研究发现，将一定量的Se元素引入Bi₂Te₃中，可在Bi₂(Te_1−xSe_x)₃复合热电材料中产生大量弥散在晶体中的缺陷和晶界，增加了对声子和低能电子的散射，有效提升了复合材料的电导率，降低了其热导率。实验结果表明，在T = 316 K时，当Se原子比例x = 0.06时，制备的Bi₂(Te_0.94Se_0.06)₃复合热电材料样品的开路电压可达到7.87 mV，Seebeck系数为−236.35 µV/K，其ZT值达到最大，为1.24。结果表明，Bi₂(Te_1−xSe_x)₃复合材料的热电特性可通过调整材料中Se原子的百分比来调控。

Abstract: By doping different atomic percentages Bi₂Se₃ in Bi₂Te₃ powdwer, Bi₂(Te_1−xSe_x)₃ composite thermoelectric materials were synthesized with hot-pressing sintering method in the special mould. The crystal structure, surface morphology, and thermoelectric properties of the synthesized samples were analyzed by XRD, SEM, and the self-made thermoelectric performance testing equipment. It was found that doping a certain amount of Bi₂Se₃ into the lattice structure of Bi₂Te₃ can produce a large number of defects and grain boundaries in the crystal micro-structures of the synthesized composite thermoelectric material samples, which increases the scattering effect of phonons and low energy electrons of the lattice, effectively enhances the conductivity, and reduces its thermal conductivity of the composite material samples. As x = 0.06, the prepared Bi₂(Te_0.94Se_0.06)₃ composite thermoelectric samples exhibited optimal thermoelectric performances at 316 K. Its open circuit thermal voltage can reach 7.87 mV, Seebeck coefficient is −236.35 µV/K, and the figure-of-merit ZT value is 1.24. It was demonstrated that the thermoelectric performance of Bi₂(Te_1−xSe_x)₃ composite thermoelectric materials can be improved by tuning the Se composition.