Yalikun Alimujiang, Lee Ming-Hsien, Mamat Mamatrishat
School of Physics and Technology, Xinjiang University Urumqi Xinjiang 830046 P. R China
Department of Physics, Tamkang University New Taipei 25137 Taiwan.
RSC Adv. 2019 Dec 17;9(71):41861-41867. doi: 10.1039/c9ra09109b. eCollection 2019 Dec 13.
The chalcopyrite structure is a rich source for the exploration of new IR materials. However, not all of the compounds with a chalcopyrite-type structure exhibit satisfactory optical properties, which may originate from their different microstructure features. In this work, we selected four classical chalcopyrite materials, AGaS (A = Ag, Cu) with normal structures and AGaS (A = Zn, Hg) with defect structures, to study their electronic structures, optical properties including the contribution of ions and ion groups to their band gaps, SHG responses and birefringences by the first-principles method. The results uncover that the different band gaps are mainly caused by the d orbitals of A* (A* = A, A)-site atoms and dp hybridizations between the A*-site and S atoms. In addition, the more powerful covalent bonds of A-S and Ga-S in the AGaS lead to the larger SHG responses of ZnGaS and HgGaS. For the birefringences, the sizes of the A*-site atoms make sense, namely larger size will lead to higher distortion of tetrahedra, then result in large birefringences. All the above analyses conclude that the A*-site atoms in the chalcopyrite structures play a modulation role in determining the optical properties.
黄铜矿结构是探索新型红外材料的丰富来源。然而，并非所有具有黄铜矿型结构的化合物都表现出令人满意的光学性质，这可能源于它们不同的微观结构特征。在这项工作中，我们选择了四种典型的黄铜矿材料，具有正常结构的AGaS（A = Ag，Cu）和具有缺陷结构的AGaS（A = Zn，Hg），通过第一性原理方法研究它们的电子结构、光学性质，包括离子和离子基团对其带隙的贡献、二次谐波响应和双折射。结果表明，不同的带隙主要由A*（A* = A，A）位原子的d轨道以及A位与S原子之间的dp杂化引起。此外，AGaS中A-S和Ga-S更强的共价键导致ZnGaS和HgGaS具有更大的二次谐波响应。对于双折射，A位原子的大小起作用，即较大的尺寸会导致四面体的更高畸变，进而导致大的双折射。以上所有分析得出结论，黄铜矿结构中的A*位原子在决定光学性质方面起调节作用。
