Na量变化对Na_xCoO_2(x=0.5,0.6)陶瓷电子结构的影响  

EFFECTS OF VARIATION IN THE CONTENT OF NA ON THE ELECTRONIC STRUCTURES OF Na_XCoO_2(X=0.5,0.6)THERMOELECTRIC CERAMIC

作　　者：马秋花[1] 张景丽[2] 王改民[1] 路朋献[1] 侯永改[1] 

机构地区：[1]河南工业大学材料科学与工程学院,郑州450007 [2]河南工业大学理学院,郑州450007

出　　处：《中国陶瓷》2011年第3期25-28,共4页China Ceramics

基　　金：河南工业大学校基金资助项目(07XJC019)

摘　　要：采用第一性原理的密度泛函理论平面波赝势法,通过广义梯度近似电子结构计算对NaxCoO2(x=0.5,0.6)进行了研究。结果表明Na0.5CoO2为直接能隙的P型半导体,带宽为1.52ev;而Na0.6CoO2为间接带隙的P型半导体,带宽为1.23ev。Co3d电子晶场的分裂,使体系呈现铁磁性,得到Na0.5CoO2和Na0.6CoO2的净磁矩分别是6μB和4μB。此外,费米面附近Na0.5CoO2的态密度较Na0.6CoO2的大且体系存在较宽的赝隙,这使得Na0.5CoO2较Na0.6CoO2有更大的Seebeck系数和电导率。The electronic structures of thermoelectric ceramic NaxCoO2（x=0.5,0.6）were investigated by first-principles calculations with pseudopotential plane-wave method and generalized approximation（GGA） based on density functional theory（DFT）.The results showed that Na0.5CoO2 is p-type indirect gap semiconductor and band-gap energy is 1.52ev;Na0.6CoO2 is p-type direct gap semiconductor and band-gap energy is 1.23ev.Split of Co3d electron crystal field causes ferromagnetism.Calculated net magnetic moment is 4μB and 6μB for Na0.5CoO2 and Na0.6CoO2 respectively.What＇s more,DOS（Density of State） of Na0.5CoO2 thermoelectric ceramic is larger than that of Na0.6CoO2 near the Femi energy and furthermore wide pseudogap exists in Na0.5CoO2,which indicate Na0.5CoO2 poses larger Seebeck coefficient and higher electrical conductivity than Na0.6CoO2.

关 键 词：电子结构 NaxCoO2热电陶瓷 热电性能 

分 类 号：TQ174.756[化学工程—陶瓷工业]