Comparative Study on Electronic Structure and Optical Properties of α-Fe 2 O 3 , Ag/α-Fe 2 O 3 and S/α-Fe 2 O 3.

The electronic structures and optical properties of pure, Ag-doped and S-doped α-Fe₂O₃ were studied using density functional theory (DFT). The calculation results show that the structure of α-Fe₂O₃ crystal changes after Ag and S doping, which leads to the different points of the high symmetry of Ag-doped and S-doped α-Fe₂O₃ with that of pure α-Fe₂O₃ in the energy band, as well as different Brillouin paths. In addition, the band gap of α-Fe₂O₃ becomes smaller after Ag and S doping, and the optical absorption peak shifts slightly toward the short wavelength, with the increased peak strength of S/α-Fe₂O₃ and the decreased peak strength of Ag/α-Fe₂O₃. However, the optical absorption in the visible range is enhanced after Ag and S doping compared with that of pure α-Fe₂O₃ when the wavelength is greater than 380 nm, and the optical absorption of S-doped α-Fe₂O₃ is stronger than that of Ag-doped α-Fe₂O₃. [ABSTRACT FROM AUTHOR]