金红石相和锐钛矿相TiO_2本征缺陷的第一性原理计算

First-principles calculation of rutile and anatase TiO_2 intrinsic defect

采用第一性原理的计算方法,分别研究了金红石相和锐铁矿相TiO_2各种缺陷态形成的类型,以及几何结构、生长气氛和Fermi能级位置对缺陷形成能的影响,从理论上预测产生点缺陷的实验条件.重点是讨论带电点缺陷的形成能,并对结果进行适当修正.研究发现,本征缺陷的类型和浓度对TiO_2的性能有一定的影响:在富O条件下,TiO_2容易形成V_(Ti)(Ti空位)缺陷;在富Ti条件下,TiO_2的Ti^(4+)_i和Vo(O空位)缺陷将大量出现,形成Schottky缺陷.

In the paper,we study how the geometry structure and the growing ambience and the Fermi level of several intrinsic point defects effect the defect formation energy of the rutile and anatase TiO_2,which type of point defect will be formed,and how to predict the experimental condition of point defect from theory.The key problem is how to calculat the defect formation energy with charge,and correcte the calculation results.The results show the defect type and the defect concentration are related to the nonequilibrium growth condition.In general,under the O-rich condition,VTi will form spontaneously,and under the Ti-rich condition,Ti4＋ and Vb easily appear in Schottky defects.