Microstructure and Thermoelectric Properties of Bi- and Cu-Substituted Ca3Co4O9 Oxides
Microstructure and Thermoelectric Properties of Bi- and Cu-Substituted Ca3Co4O9 Oxides
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DOI：
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发表时间：
2009-10
影响因子：
10.9
通讯作者：
Haoshan Hao;Limin Zhao;Xing Hu
中科院分区：
文献类型：
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作者：
Haoshan Hao;Limin Zhao;Xing Hu
采用传统的固相反应法制备了Bi型和Cu型Ca3Co4O9样品，研究了元素替代对样品的微观结构和热电性能的影响。由于空穴浓度的增加，Cu部分取代Co导致电导率增加，Seebeck系数减小。与未掺杂的Ca3Co4O9相比，掺铜样品的微观结构几乎没有变化。而在Ca2.7Bi0.3Co4O9中，部分掺杂使晶体尺寸显著增大，并形成c轴取向结构，电导率明显提高。铜、铋共替代进一步提高了Ca2.7Bi0.3Co3.7Cu0.3O9的晶粒长大和电导率。因此，铜和铋共替代样品在高温下具有最佳的热电性能，在1000K时功率因数最高可达3.1×10−4Wm−1·K−2。
Biand Cu-substituted Ca3Co4O9 samples were prepared by conventional solid-state reaction method and the effect of element substitution on the microstructures and thermoelectric properties was investigated. Partial substitution of Cu for Co leads to an increase in electrical conductivity and a decrease in Seebeck coefficient due to the rise of hole concentration. The microstructure of Cu-substituted sample is almost unchanged compared with undoped Ca3Co4O9. On the other hand, partial substitution of Bi for Ca gives rise to a significant increase in the grain size, and c-axis-oriented structure can be formed in Ca2.7Bi0.3Co4O9, resulting in an obvious increase in electrical conductivity. Cu and Bi co-substitution further increases the grain growth and the electrical conductivity of Ca2.7Bi0.3Co3.7Cu0.3O9. Thus, Cu and Bi co-substitution samples possess the optimal thermoelectric performance at high temperature and the highest value of power factor can reach 3.1×10−4 Wm−1·K−2 at 1000 K.