P型Si_(80)Ge_(20)B_(0.6)-SiC纳米复合材料的微观结构与热电性能研究（英文）

Microstructure and Thermoelectric Properties of p-type Si_(80)Ge_(20)B_(0.6)-SiC Nanocomposite

采用感应熔炼、球磨与放电等离子烧结的方法制备了SiC第二相均匀分布的Si_(80)Ge_(20)B_(0.6)-SiC纳米复合热电材料。系统研究了细化Si_(80)Ge_(20)B_(0.6)晶粒尺寸与复合SiC纳米颗粒对材料热电性能的影响。球磨导致的Si_(80)Ge_(20)B_(0.6)晶粒尺寸的降低显著增加了材料的晶界数量,进而增强了晶界对中长波声子的散射,能够有效降低材料的晶格热导。Si_(80)Ge_(20)B_(0.6)基体中均匀分布的纳米SiC颗粒提供了额外的散射中心和界面,可进一步增强声子散射,降低材料的晶格热导。在纳米结构化与SiC纳米复合的共同作用下,材料在1000 K时热电优值ZT达到了0.62,较基体提高了17%。证明纳米结构化与纳米复合方法能够共同作用于硅锗合金,提高其热电性能。

P-type silicon germanium （SiGe） alloys, Si80Ge20B0.6, with homogeneously dispersed SiC nanoparticles were prepared by ball milling and subsequent spark plasma sintering. The influence of grain size reduction of SiGe matrix and SiC nanoparticle dispersion on electrical and thermal transport properties were investigated. A significant reduction in lattice thermal conductivity is achieved by a more pronounced grain boundary scattering of phonons in- troduced by grain size reduction after ball milling. Dispersing SiC nanoparticles in the Si80Ge20B0.6 matrix effectively reduces the conduction of heat by providing additional phonon scattering centers. A dimensionless figure-of-merit （ZT） of 0.62 at 1000 K is obtained in nanostructuring Si80Ge20B0.6 incorporated with only 0.5vo1% SiC nanoparticles, which is 17% higher than the parent Si80Ge20B0.6 matrix and about 30% higher than p-type SiGe alloy used in the radioisotope thermoelectric generator in space missions.