摘要
采用密度泛函离散变分方法计算了Ca位掺杂对Ca3Co4O9的电子结构和化学键的影响,讨论了它们与热电性能之间的关系。结果表明,掺Sr体系的能隙宽度仍表现出半导体特征,与未掺杂的相比,能隙变窄;在费米能级附近主要由体系的Co 3d和O 2p做贡献,在Ca2CoO3和CoO2层,Co 3d对价带和导带的贡献值不同。掺Sr后,通过计算共价键级平均值和分子波函数轨道以及净电荷值可知,体系的共价键级和原子净电荷均比未掺杂体系减弱,且Ca2CoO3层中O原子的电子结构和键级在ab面和c轴方向表现出各向异性特征。由此推断,掺Sr体系的热电性能将有所改善。
The relations among electronic structure, chemical bonds and thermoelectric properties of Ca3 Co409 with St-doped are an- alyzed by density function and discrete variation method （ FT＇-DVM ）. The results include that the property of semiconductor is shown by the gap of the highest valence band （HVB） and the lowest conduction （ LCB ）, and the gap becomes narrower than CazCo409 ,and that HVB and LCB are mainly contributed from Co 3d and O 2p atomic orbitals. However,there are some difference of Co 3d contribution to HVB and LCB between CaCoO3 layer and CoO2 layer. Furthermore,it can be found by comparing covalent bonds, molecular orbitals and net charges with non-doped system that the covalent and ionic bonds of Sr-doped one are both weaker than those of Ca3 Co409, and that electronic structure and chemical bonds of oxygen atom in Ca2 CoO3 layer of Sr-doped are shown anisotropy property obviously and the chemical bond along c axis is stronger than that of ab-plane. The thermoelectric properties of Ca3 Co409 can be improved by replacing the Ca-site atoms with Sr atoms.
出处
《化学研究与应用》
CAS
CSCD
北大核心
2013年第10期1392-1396,共5页
Chemical Research and Application
基金
国家自然科学基金项目(50802025)资助
河南理工大学博士基金资助
关键词
失配层结构
电子结构
化学键
热电性能
misfit-layer structure
electronic structure
chemical bonds
thermoelectric property
