变价稀土元素Eu掺杂BiCuSeO热电性能的研究

Effect of Rare-earth Variable-valence Element Eu doping on Thermoelectric Property of BiCuSeO

作为一种适于中温下使用的极具发展前景的新型热电材料,BiCuSeO由于本征热导率低且Seebeck系数较高而广受关注。本研究探索了变价稀土元素Eu替换Bi位对BiCuSeO热电材料微观组织和热电性能的影响。实验结果显示,样品中同时存在Eu^2+和Eu^3+两种价态的离子,掺杂Eu元素不仅可以增加样品的载流子浓度,还可以调整样品的能带结构,进而改善样品的电输运性能,Bi0.85Eu0.15CuSeO电导率显著提升,在823 K时达到了98 S·cm^–1,相比于未掺杂样品提升了将近6倍。在温度为823 K时,Bi0.975Eu0.025CuSeO的功率因子可达0.32 mW·m^–1·K^–2,ZT值为0.49。本研究表明,掺杂变价稀土元素可以有效改善BiCuSeO热电材料的性能。

As a new promising thermoelectrical material in the range of intermediate temperature,BiCuSeO attracts much attention due to the combination of low intrinsic thermal conductivity and relatively high Seebeck coefficient.In this study,the effects of substituting variable-valence rare-earth element Eu for Bi site on the microstructure and thermoelectric performance of BiCuSeO-based material were investigated.The results indicate that ions of two valence states,Eu^2+and Eu^3+,coexist in the doped BiCuSeO samples.The doping of Eu not only improves the concentration of the carriers,but also modifies the band structure of BiCuSeO matrix,resulting in effective improvement of electrical transport properties.The electrical conductivity of Bi0.85Eu0.15CuSeO reaches 98 S·cm^–1 at 823 K,which is 6 times as high as that of the undoped sample.The power factor of 0.32 mW·m^–1·K^–2 and ZT of 0.49 can be achieved at 823 K for Bi0.975Eu0.025CuSeO sample.This study shows that the doping of variable-valence rare-earth elements can effectively improve the thermoelectric properties of BiCuSeO.