Enhanced thermoelectric performance of BiCuSeO through composite structuring with Pb-and La-doped components
摘要
BiCuSeO is the most promising mid-high temperature thermoelectric material for application. The thermoelectric properties of BiCuSeO are greatly improved by the composited structure based on Pb-doped samples with high carrier concentration and La-doped samples with high mobility. The synthesis of composited samples includes powder preparation by mechanical alloying and block forming by high-temperature spark plasma sintering. The experimental results indicate that the composited structure composed of Pb-doped high carrier sample and La-doped high- mobility sample can effectively enhance the power factor, for that reason the composited structure enables carriers to migrate through the high-mobility region, which is conducive to improving the electrical conductivity. The thermal conductivity is maintained at a low level because there exist a lot of two-phase interfaces in the modulation samples, which is conducive to the scattering of low-frequency phonons. Through the double coordination adjustment of electron and phonon, the highest ZT was increased to ~ 1.26 at 873 K.