B掺杂p型SiGe合金的制备与热电性能表征

Preparation and thermoelectric properties of B-doped p-type SiGe alloys

摘要:

SiGe合金作为一种重要的高温热电材料一直被广泛关注并得到商业应用,其n型SiGe合金热电材料的无量纲热电优值(ZT)取得较大进步,但是p型SiGe合金的ZT值仍然较低。本文,以一定化学计量比均匀混合的Si、Ge、B混合粉末为原材料,使用放电等离子烧结(SPS)系统一步法合金化制备了p型Si80Ge20Bx(x=0.5,1.0,2.0)合金热电材料,并对样品的组成、微观形貌、热电性能进行了表征与分析。结果表明,放电等离子烧结过程实现原位合金化并烧结为块体材料。随着B掺杂量的增加,电导率明显提升,热导率显著下降,当温度为950 K时,热导率为1.79 W /(m?K)。在1050 K时,ZT值达到了0.899。球磨和掺杂的协同作用使得SiGe结构基体中产生不同类型的缺陷特征而散射不同波长的声子,导致硅锗合金热导率的降低。

Abstract:

As an important high-temperature thermoelectric materials, SiGe alloy has been concerned and used widely. Although the dimensionless thermoelectric merit (ZT) of n-type SiGe alloys thermoelectric material has made much great progress, the ZT of p-type SiGe alloys is still low. In this paper, p-type Si80Ge20Bx (x = 0.5, 1.0, 2.0) alloys thermoelectric materials were prepared by one-step alloying method using Si, Ge and B powders as raw materials. The composition, microstructure and thermoelectric properties of the samples were characterized and analyzed. The results show that, in-situ one-step alloying followed by spark plasma sintering can be realized and bulk materials can be obtained. With the increase of B doping content, the electrical conductivity increases significantly and the thermal conductivity decreases significantly. When the temperature is 950 K, the thermal conductivity is 1.79 W/(m K). At 1050 K, ZT reaches the maximum value of 0.899. Due to the synergistic effect of ball milling and doping, different types of defects are produced in SiGe structure matrix resulted in scattering of different wavelengths of phonons, leading to the decrease of thermal conductivity of SiGe alloy.