Zhang Chang-Wen

The Electronic Structure and Optical Properties of Ag-Doped SnO2 Monolayer

The electronic structure and optical properties of Ag-doped SnO2 monolayer are investigated using first-principles FLAPW method. The results show that Ag:SnO2 monolayer is a direct-gap semiconductor, and band gap becomes narrow. Several obvious optical absorption peaks are observed in low energy region in Ag-doped SnO2 monolayer. The (Ag,Vo) co-doped SnO2 monolayer has a wider impurity band and narrower gap. The optical spectrum edges shift to lower energy region and enhance visible and infrared photocatalytic activity. The absorb capacity become stronger in visible region with increasing Ag concentrations. These findings can be utilized in producing new-style solar cell and light sensor.

Electronic structures and magnetic properties in SmCo7–xMx

The electronic structures and magnetic properties of SmCo7-xMx (M = Ti, Si, Zr, Hf, Cu, B, Ag, Ga, Mn) compounds are investigated by using a spin-polarized MS-X.α method. The results show that the long-range ferromagnetic order is determined by a stronger 3d_5d interaction, rather than the traditional RKKY interaction, and the effects of doping element M on 3d_5d coupling are negligible in Sm-Co-based compounds. The nonmagnetic dopant Si atoms have a larger effect on the moments of 2e site although they preferably occupy the Co 3g sites, which results in the stronger uniaxial anisotropy of this compound. Analysis of the formation energies indicates that 5d-element doped compounds are more stable than other dopants, and furthermore, they have a higher Curie temperature above room temperature, which will be in favor of their potential application as high-temperature permanent magnets.