中国物理B ›› 2007, Vol. 16 ›› Issue (12): 3798-3802.doi: 10.1088/1009-1963/16/12/040

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First-principles study on the electronic structure and optical properties of Tl2Cd2(SO4)3 and Rb2Cd2(SO4)4

徐 斌1, 易 林1, 成 泽1, 程正则2   

  1. (1)Department of Physics, Huazhong University of Science and Technology, Wuhan 430074, China; (2)Department of Physics, Huazhong University of Science and Technology, Wuhan 430074, China;Department of Physics, Xianning College, Xianning 437005, China
  • 出版日期:2007-12-20 发布日期:2007-12-20
  • 基金资助:
    Project supported by the National Science Foundation of China (Grant No~2006CB921605) and the National Natural Science Foundation of China (Grant Nos~10174024 and 10474025).

First-principles study on the electronic structure and optical properties of Tl2Cd2(SO4)3 and Rb2Cd2(SO4)4

Xu Bin(徐斌)a) Cheng Zheng--Ze(程正则)a)b)†, Yi Lin(易林)a), and Cheng Ze(成泽)a)   

  1. a Department of Physics, Huazhong University of Science and Technology, Wuhan 430074, China; b Department of Physics, Xianning College, Xianning 437005, China
  • Online:2007-12-20 Published:2007-12-20
  • Supported by:
    Project supported by the National Science Foundation of China (Grant No~2006CB921605) and the National Natural Science Foundation of China (Grant Nos~10174024 and 10474025).

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摘要： With the help of ab initio full-potential linearized augmented plane wave (FPLAPW) method, calculating the electronic structure and linear optical properties is carried out for $X$Cd$_{2}$(SO$_4$)$_{3}$ ($X=$Tl, Rb). The results show that Tl$_{2}$Cd$_{2}$(SO$_4$)$_{3}$ (TlCdS) has a larger band gap than Rb$_{2}$Cd$_{2}$(SO$_4$)$_{3}$ (RbCdS) and the energy bands for RbCdS are more dispersive than those of TlCdS. From their partial densities of states (PDOS), we have observed that the hybridization between S ionic 2p and O atomic 2p orbitals forms SO$_{4}$ ionic groups. The remarkable difference between RbCdS and TlCdS is, however, the degree of hybridization between cation (Tl and Rb) and its surrounding oxygen atoms. In the view of quantum chemistry, the strong p-d hybridization indicates the existence of their cation ionic bonds (Cd-O, Rb-O, and Tl-O). The calculations of TlCdS and RbCdS show their optical properties to be less anisotropic. Their anisotropies in the optical properties mainly occur in a low photon energy region of 5--16 eV.

关键词: langbeinite, electronic structure, band gap, optical properties

Abstract: With the help of ab initio full-potential linearized augmented plane wave (FPLAPW) method, calculating the electronic structure and linear optical properties is carried out for $X$Cd$_{2}$(SO$_4$)$_{3}$ ($X=$Tl, Rb). The results show that Tl$_{2}$Cd$_{2}$(SO$_4$)$_{3}$ (TlCdS) has a larger band gap than Rb$_{2}$Cd$_{2}$(SO$_4$)$_{3}$ (RbCdS) and the energy bands for RbCdS are more dispersive than those of TlCdS. From their partial densities of states (PDOS), we have observed that the hybridization between S ionic 2p and O atomic 2p orbitals forms SO$_{4}$ ionic groups. The remarkable difference between RbCdS and TlCdS is, however, the degree of hybridization between cation (Tl and Rb) and its surrounding oxygen atoms. In the view of quantum chemistry, the strong p-d hybridization indicates the existence of their cation ionic bonds (Cd-O, Rb-O, and Tl-O). The calculations of TlCdS and RbCdS show their optical properties to be less anisotropic. Their anisotropies in the optical properties mainly occur in a low photon energy region of 5--16 eV.

Key words: langbeinite, electronic structure, band gap, optical properties

中图分类号:  (Other inorganic compounds)

  • 71.20.Ps
71.15.Ap (Basis sets (LCAO, plane-wave, APW, etc.) and related methodology (scattering methods, ASA, linearized methods, etc.)) 78.20.Ci (Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity))