硼掺杂球磨SiGe合金的热电性能

SiGe合金热电材料作为一种传统的高温热电材料一直以来受到广泛关注。本研究通过B在球磨SiGe合金中的P型掺杂,有效增加了材料的载流子浓度,优化材料的电学性能。通过球磨降低材料的晶粒尺寸,增强晶界对声子的散射,降低材料的晶格热导率。另外,B掺杂使点缺陷散射和载流子-声子散射得到增强,材料的晶格热导率进一步降低。在室温时,Si_(0.8)Ge_(0.2)B_(0.04)的晶格热导率为~4Wm~(-1) K~(-1)。由于掺杂后电导率提高,热导率降低,因此热电优值zT得到了提高。在850K时,Si_(0.8)Ge_(0.2)B_(0.04)的最大热电优值为0.42,与Si_(0.8)Ge_(0.2)B_(0.002)的样品相比,其优值提高了2.5倍左右。

Thermoelectric Properties of Boron Doped SiGe Alloys by Ball Milling

SiGe alloy based thermoelectric(TE) materials have attracted widely attention for decades as a kind of traditional high temperature TE materials.In this study,p-type B doped SiGe alloys were prepared by ball milling.B doping effectively increases the carrier concentration and optimizes the electrical properties.Lattice thermal conductivity of the material is reduced by the enhanced boundary scattering which is caused by the reduced grain sizes due to ball milling.In addition,lattice thermal conductivity of the material is further reduced due to the point defect scattering and carrier-phonon scattering caused by doping.At room temperature,the thermal conductivity of Si0.8 Ge0.2 B0.04 is ～ 4Wm-1 K 1.Due to the improvement of the electrical transport properties and the decreased thermal conductivity,the figure of merit zT is improved.The maximum figure of merit zT reaches 0.42 for the sample Si0.8Ge0.2B0.04 at 850K,2.5 times higher than that of Si0.8 Ge0.2 B0.002.