SiC对粉碎烧结法制备P型Bi_(0.5)Sb_(1.5)Te_(3)合金热电性能的影响

Effect of SiC on thermoelectric properties of P-type Bi_(0.5)Sb_(1.5)Te_(3) alloy prepared by pulverizing and sintering method

向粉碎法制备的Bi_(0.5)Sb_(1.5)Te_(3)+5%Te(质量分数)合金粉体中混入不同体积分数的SiC颗粒,利用放电等离子体烧结法制备SiC复合块体材料,探究块体材料组织和热电性能的变化规律。研究发现:随着SiC体积分数的增加,块体材料的取向性弱化,组织细化,载流子浓度增加,迁移率降低;由于取向性弱化及组织细化,加强了声子散射,降低了晶格热导率。由于SiC复合块体材料的电学性能恶化,块体材料的无量纲热电优值(ZT)并未获得显著的提升;当SiC体积分数为0.40%时,SiC复合块体材料在322 K时具有最优的无量纲热电优值(ZT=~0.81)。

SiC particles in the different volume fraction were mixed into Bi_(0.5)Sb_(1.5)Te_(3)+5%Te alloy powders(mass fraction)prepared by the pulverizing method.The mixed powders were sintered into the blocks by spark plasma sintering(SPS)method.The microstructure and thermoelectric properties of these block samples were investigated.The results show that,with the increase of SiC volume fraction,the orientation of the bulks is weakened,the microstructure is refined,the carrier concentration increases,and the mobility decreases.Due to the weakened orientation and the refined microstructure,the scattering of phonons is enhanced,leading to a reduced lattice thermal conductivity.However,due to the deterioration of the electrical properties for the blocks,the dimensionless thermoelectric value(ZT)of the bulks with SiC has no improvement.When the volume fraction of SiC is 0.40%,the block samples show the best thermoelectric performance with ZT=~0.81 at 322 K.