氟氯磷灰石固溶体晶体性质的密度泛函理论研究

Crystal Structures of Fluor-chlorapatite Solid Solution: DFT Investigation

基于密度泛函理论(DFT)研究了氟磷灰石、氯磷灰石及不同Cl含量的氟氯磷灰石固溶体晶体结构和电子性质。结果表明,随着Cl含量增加,体系能量趋于增大,同时晶体结构中a,b值呈增大趋势,c值却逐渐变小。态密度分析显示,Cl取代F后,Cl3s态较F 2s态向右移动,且在价带顶部Cl 3p态更靠近费米能级,同时峰费米能级附近Ca_23d态也更活跃。电荷分析显示Cl取代F后,主要电荷转移发生在通道原子F、Cl以及金属Ca;Mulliken键布居显示Ca_2—Cl较Ca_2—F键布居值更大且键长更长,其中在氯磷灰石中Ca_2—Cl键长达到了0.2608 nm。

The structure and electronic properties of the fluorapatite, chlorapatite and their solid solution are investigated based on DFT theory. The results show that as C1 increases, the energy increases, and the lattice parameters a, b also increase, but c decreases. DOS analysis indicates that after C1 replaces F, C1 3s state moves to right to a higher level compared with F 2s state, and C1 3p state is closer to the Femi level. At the same time, Ca2 3d state near the Femi level is more active. The Mulliken atomic charge analysis reveals that the charge transfer mainly occurs on the atom F, C1 and Ca. The Mulliken bond population analysis show that the Ca2--Cl population is larger and longer than the Ca2--F, even reaching 0.2608 nm in chlorapatite.