Ge掺杂MnTe材料的热电输运性能

Thermal and Electrcial Transport Properities of Ge Doped MnTe Thermoelectrics

MnTe作为一种新型的无铅p型热电材料,在中温区热电领域具有广阔的应用前景,但其本身的热电性能不足以与高性能n型热电材料相匹配。本研究通过真空熔炼–淬火和放电等离子烧结的方法制备不同Ge掺杂量的致密且均匀的Mn_(1.06–x)Ge_(x)Te(x=0,0.01,0.02,0.03,0.04)多晶块体样品。过量的Mn可以有效抑制MnTe_(2)相,提高基体相的热电性能。通过掺杂4%Ge粉末,材料的载流子浓度提高到7.328×10^(18)cm^(–3),电导率在873 K增大到7×10^(3)S·cm^(–1),功率因子提升至620μW·m^(–1)·K^(–2)。同时,通过点缺陷增强声子散射使材料的热导率降低到0.62 W·m^(–1)·K^(–1),实现了对材料电声输运性能的有效调控。Mn_(1.02)Ge_(0.04)Te在873 K获得了0.86的热电优值ZT,较纯MnTe材料提高了43%。

MnTe is a promising candidate for the p-type lead-free thermoelectric material in middle temperature application.However,its thermoelectric performance isn’t qualified for some conventional n-type materials to form efficient thermoelectric devices.In this study,Mn_(1.06–x)Ge_(x)Te(x=0,0.01,0.02,0.03,0.04)polycrystalline block samples with different Ge doping contents were efficiently synthesized by vacuum melting quenching and spark plasma sintering.The as-obtained Mn_(1.06–x)Ge_(x)Te bulk was dense and consisted of homogeneous composition.Tiny extensive Mn can effectively restrict the formation of the second phase of MnTe_(2)and improve the thermoelectric properties of the matrix phase.Electrical conductivity of the materials increasing to 7×10^(3)S·cm^(–1)results from the enhanced carrier concentration 7.328×10^(18)cm^(–3)at 873 K,which contributed to a power factor of 620μW·m^(–1)·K^(–2) by 4%Ge doping.Meanwhile,Mn_(1.06–x)Ge_(x)Te showed the reduced thermal conductivity of 0.62 W·m^(–1)·K^(–1) by enhanced phonons scattering intensified with point defects,realizing the effective regulation of both electrical-and thermal-transport properties.Mn_(1.02)Ge_(0.04)Te achieved a thermoelectric performance of 0.86 at 873 K,which evolved by 43%compared with the pristine sample.