Xu Shuhong, Wang Chunlei, Wang Zhuyuan, Cui Yiping
Advanced Photonics Center, School of Electronic Science and Engineering, Southeast University, Nanjing, 210096, China.
J Mol Model. 2014 Apr;20(4):2184. doi: 10.1007/s00894-014-2184-x. Epub 2014 Mar 16.
In experiment, doped Ag:ZnSe nanocrystals (NCs) had better stability than that of ZnSe nanocrystals under ambient atmospheres in the presence of air and light illumination. However, it is difficult to explain the mechanism of better stability of Ag:ZnSe nanocrystals from the experiment perspective for doped nanocrystals are more unstable than corresponding pure nanocrystals in general. Using B3LYP/LANL2DZ method, we have investigated the geometrical structures, bonding characters, and molecular orbitals (MOs) of hexagonal and tetrahedral Ag doped ZnSe structures in theory. The results showed that the good stability of Ag:ZnSe nanocrystals can be attributed to the stronger binding between Ag and Se. Moreover, we have proved that Ag doped ZnSe nanocrystals synthesized in experiment should be substituting doped but not vacuity doped. Substituting Ag doped ZnSe molecules have the same configuration as that of the ZnSe structure, but vacuity doped Ag:ZnSe have completely different configuration than ZnSe structure due to the big size of Ag atom. In addition, through contrast of MO of ZnSe and Ag doped ZnSe, we have testified that Ag easily formed bonds with Se. The high binding energy and high probability of forming bonds with Se atom make Ag doped ZnSe nanocrystals have better stability than that of ZnSe nanocrystals.
在实验中，掺杂的Ag:ZnSe纳米晶体（NCs）在有空气和光照的环境气氛下比ZnSe纳米晶体具有更好的稳定性。然而，从实验角度很难解释Ag:ZnSe纳米晶体具有更好稳定性的机制，因为一般来说掺杂纳米晶体比相应的纯纳米晶体更不稳定。我们使用B3LYP/LANL2DZ方法从理论上研究了六方和四面体Ag掺杂ZnSe结构的几何结构、键合特征和分子轨道（MOs）。结果表明，Ag:ZnSe纳米晶体的良好稳定性可归因于Ag和Se之间更强的结合。此外，我们证明了实验中合成的Ag掺杂ZnSe纳米晶体应为取代掺杂而非空位掺杂。取代型Ag掺杂ZnSe分子与ZnSe结构具有相同的构型，但空位掺杂的Ag:ZnSe由于Ag原子尺寸较大，其构型与ZnSe结构完全不同。此外，通过对比ZnSe和Ag掺杂ZnSe的MO，我们证实了Ag容易与Se形成键。高结合能以及与Se原子形成键的高概率使得Ag掺杂ZnSe纳米晶体比ZnSe纳米晶体具有更好的稳定性。
