| Using the CASTEP modules of Materials Studio computational simulation software, the electronic structure and magnetic properties of the 3d transition metals(TM = Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn) doped the monolayer WS2, the electronic structures and optical properties of the 4d transition metals(TM = Y, Zr, Nb, Mo, Pd, Cd) doped single layer WS2, and the influence of the H modifying ways on the electromagnetic characteristics of the armchair WS2 nanoribbons are investigated in this paper. And then get some conclusions as follows:(1) After doping the transition metal atoms(TM = Ti, V, Cr, Mn, Fe, Co, N i, Cu, and Zn),the system supercell structures will present the lattice distortion to a certain extent and the band structure and magnetic properties of WS2 will be influenced;the different systems exhibit the different magnetic moments, the V-doped WS2 has metallic ferromagnetism, Fe-, Cr-, Cu-, Zn-doped WS2 exhibit a semiconductor property, and Ti-, Mn-, N i-doped WS2 are semi- metallic ferromagnetic, whose semi- metal band gaps are 0.025 e V, 0.4e V, 0.125 e V, respectively. The Co-doped also exhibits semiconductor properties, produces max magnetic moment(3.24268μB), and shows ferrimagnetic.(2) The effects of the different Fe doping concentration on the electromagnetic properties of the single- layer WS2 are calculated, and the results show that the energy band structures of the system become from the direct band gap into indirect band gap with the reducing impurity concentration, and then change from the indirect to the direct. The total magnetic moments of the systems are increasing substantially.(3) By the analysis of the total spin and partial density of states of the systems, in the systems of V, Cr, Mn, Fe, Co, and Ni doping, The magnetic mechanism is mainly the exchange correlation effect of the transition metal d orbits and the p orbits of the nearest neighbor S atoms.(4) For the 4d transition metal doping, the energy band structures after geometry optimization show that the rest are introduced into a number of the impurity levels besides the elements Mo, and the impurity levels of the Y, Zr, Nb, and Pd-dopedprimarily stem from the hybridization between the d-state electrons of the impurity atoms and S-p electrons; and the Cd doping is rather special, Cd-d states don’t contribute to the impurity levels in the gap band in that Cd-d states are not very lively and mainly localized in the valence band of-8.75 e V. For the different doping systems, their optical constants of the spectrum are different, and specially, the Y, Cd doped have a strong absorption spectrum in the near infrared and visible region, which may have potential applications in the infrared detectors and the light catalysis.The differential charge density of the intrinsic WS2 and the Mo, Y doped WS2 reflects the charge gains and losses and the charge transfer before and after doping. Mo doped WS2 has little impact on the differential charge density distribution, but the pros and cons of the electrons and the accumulation and loss of charge are different. The differential charge density of the Y-doped WS2 has the larger the distortion.(5) Based on the density functional theory, the electromagnetic properties of the armchair WS2 nanoribbons of the symmetric and asymmetric H modifying are calculated. With the increasing number of the modifying H atoms, the structure of the armchair WS2 nanoribbons becomes more stable, caused the nanoribbons to transition between indirect-gap semiconductor,semi- metal and direct- gap semiconductor,it may stem from the different occupation number of electrons with H modifying.The energy bands near the Fermi level contribute to edge states. The intrinsic AWS2 NR has no magnetism, and the system shows the magnetic moments of different values after adding H. The 6H-AWS2 NR occupies the largest magnetic moment, up to 2.55301μB, these different magnetic moments due to the effect of the ligand field of W-d orbits leading to varying degrees of orbit splitting. |
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