本文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热电陶瓷Na<,0.6>CoO<,2>进行了研究.结果表明Na<,0.6> CoO<,2>为间接带隙的P型半导体,带隙宽度为1.233 eV.从态密度及电荷差分密度可知Co<,3>d电子和O2p电子对价带顶及导带底的贞献较大,CO3d与O2p轨道的杂化利于载流子的迁移,此外,CO3d电子晶场的分裂,使体系呈现自旋极化,计算得到的净磁矩为4μ<,B>,而自旋磁矩的存在是获得高Seebeck系数的原因.
参考文献
| [1] | Sasago T Y;Uchinokura K .Large thermoelectric power in NaCo《,2》O《,4》 single crystsls[J].Physical Review B,1997,56:12685-12688. |
| [2] | Fouassier C;Matejka G;Beau J M et al.Sur de nouveaux bronzes oxygenes de formule Na《,x》 CoO《,2》(x≤I) Le systeme cobalt oxygene sodium[J].Journal of Solid State Chemistry,1973,6:5322-5537. |
| [3] | Monkhorst H J;PackJ D .Special points for brillouin-zone integrations[J].Physical Review B,1976,13:5188-5192. |
| [4] | Mikio Ito;Tomoya Nagira;Daisuke Furumoto;Shigeru Katsuyama;Hiroshi Nagai .Synthesis of Na_xCo_2O_4 thermoelectric oxides by the polymerized complex method[J].Scripta materialia,2003(4):403-408. |
| [5] | D.J.SINGH;D.KASINATHAN .Thermoelectric Properties of Na_xCoO_2 and Prospects for Other Oxide Thermoelectrics[J].Journal of Electronic Materials,2007(7):736-739. |
| [6] | Wang CH;Chen XH;Wu T;Luo XG;Wang GY;Luo JL .In-plane ferromagnetism in charge-ordering Na0.55CoO2[J].Physical review letters,2006(21):6401-1-6401-4-0. |
| [7] | Singh DJ. .Quantum critical behavior and possible triplet superconductivity in electron-doped CoO2 sheets - art. no. 020503[J].Physical review, B. Condensed matter and materials physics,2003(2):503-0. |
| [8] | Wang YY.;Rogado NS.;Cava RJ.;Ong NP. .Spin entropy as the likely source of enhanced thermopower in NaxCo2O4[J].Nature,2003(6938):425-428. |
| [9] | Terasaki I.;Uchinokura K.;Sasago Y. .LARGE THERMOELECTRIC POWER IN NACO2O4 SINGLE CRYSTALS[J].Physical Review.B.Condensed Matter,1997(20):12685-12687. |
上一张
下一张
上一张
下一张
计量
- 下载量()
- 访问量()
文章评分
- 您的评分：
-
10%
-
20%
-
30%
-
40%
-
50%