Ca_3Co_2O_6与掺铜体系的量子化学计算

Quantum Chemical Calculation of Ca_3Co_2O_6 and Cu-doped System

采用离散变分密度泛函方法计算了Ca3Co2O6及掺铜体系,讨论了电子结构、化学键等与热电性能之间的关系。结果表明,一维Co-O链对材料的电学性能起着主导作用,Ca-O之间的弱结合导致材料具有较低的热导率。价带和导带主要由Co3d、Cu3d和O2p原子轨道贡献,价带和导带之间的能隙宽度表现半导体电子结构特征,且掺铜体系的能隙变窄,离子键和共价键减弱。由此推断,掺铜后体系的热电性能将有所改善。

The electronic structure of Ca3Co2 O6 and Cu-doped system are calculated using the functional and discrete variation method. The relation between the electronic structure, chemical bond and the thermoelectric property is discussed. The results indicate that the 1D Co-O chains play an important role in the electric property and the weak bond between Ca and O may induce the low thermal conductivity. The highest valence band （HVB） and the lowest conduction （LCB） are mainly offerred by Co3d, Cu3d and O2p atomic orbitals. The property of semiconductor is shown from the gap between HVB and LCB. The gap of Cu-doped system is less than that of Ca3 Co2O6. The covalent and ionic bonds of Cu-doped system are both weaker than those of Ca3Co2O6. The thermoelectric property may be improved by adding Cu element into the system of Ca3Co2O6.