Lu_(2)O_(3):Tm发光材料的第一性原理计算研究

First-principles calculation of Lu_(2)O_(3):Tm luminescent materials

采用基于密度泛函理论的第一性原理计算,研究了稀土离子Tm掺杂Lu_(2)O_(3)晶体的发光机理.通过计算材料的晶体结构和形成能,发现Tm离子更倾向于掺杂进入Lu_(2)O_(3)晶胞的C_(2)位置.分析电子结构发现,稀土离子Tm的掺杂,会在带隙处引入杂质能级,有利于电子的跃迁,并且Tm离子在C_(2)位置掺杂比在S_(6)位置更能起到发光中心的作用.因为Tm离子在C_(2)位置为电荷转移型跃迁(CTT型),而在S_(6)位置为部分允许的4f→4f 5d电偶极跃迁.通过吸收特性的计算模拟发现C_(2)位置的吸收峰更宽,因此Tm离子在Lu_(2)O_(3)C_(2)位置掺杂更有利于发光.本研究为制备具有增强光学性能的新型发光材料提供预测和理论指导.

Herein,the luminescence mechanism of rare earth ion Tm doped Lu_(2)O_(3)crystals was studied by first principles calculation based on density functional theory.By calculating the crystal structure and formation energy of the materials,it was found that Tm ions were more easily doped into the C_(2)site of Lu_(2)O_(3)cells than that of S_(6)position.By analyzing the electronic structure,it was obvious that the doping of rare earth ion Tm would introduce impurity levels into the band gap,which was conducive to the electron transition,and the doping of Tm ion in C_(2)position could play the role of luminescence center better than that in S_(6)site.Because Tm ion present a transition of charge transfer type(CTT type)at the C_(2)site and a partially permissible 4f→4f 5d electric dipole transition at the S_(6)position.Through the simulation of absorption characteristics,it was found that the absorption peak at C_(2)site was wider than that of S_(6)site,so the doping of Tm ion at Lu_(2)O_(3)in C_(2)position was more beneficial to luminescence.This study provides prediction and theoretical guidance for the preparation of novel luminescent materials with enhanced optical properties.