First-principles Calculations On Doped Anatase TIO2Diluted Magnetic Semiconductor

Titanium dioxide (TiO2) has been extensively researched in recent years. Anatase TiO2nanocrystals/nanosheets have been successfully synthesized and TiO2nanomaterials have become a hot spot in the field of materials science because of its special optical and electronic properties. TiO2nanomaterials also have a high chemical stability, thermal stability, non-toxic, ultra-hydrophilic, non-migratory and can contact with food directly. So they are. widely used in UV materials, textiles, photocatalytic catalyst, self-cleaning glass, sunscreen, paint, ink, food packaging materials, paper industry and aerospace industry. TiO2nanomaterials have a very promising future. Research and utilization of them will bring huge changes to people’s lives.However, TiO2has a wide band gap (3.2eV for anatase and3.0eV for rutile), that allows excitation only under ultraviolet radiation which have only5%in the Solar spectrum at the earth’surface. For the purpose of ameliorating the photocatalytic activity as well as absorption of the visible radiation, TiO2has been doped mainly two types of elements, transition metal elements and non-metallic elements. The former is one of the more effective methods. So far, TiO2has been doped by various sorts of transition metals, including Cu, Ag, Au, V, Cr, Fe, Co, Ni, Nb, Mo, and Mn. Doping these transition metals can extend TiO2’range of light response to visible radiation and create impurity levels in TiO2’band so as to effectively separate electrons and holes, thus extending the lifetime of carriers. In recent years,Researchers have done some research about Mn-doped TiO2nanoparticles and their results show that the Mn-doped TiO2has higher photodegradation efficiency than that of undoped TiO2upon its exposure to visible light.We performed first-principles calculations for two Mn-doped structures in which Mn atoms substitute Ti atoms to determine whether (i) it is more conducive to Mn ion doping and (ii) ferromagnetism can occur in F adsorption anatase TiO2surfaces. Ferromagnetic (FM) coupling is more stable than antiferromagnetic (AFM) coupling for all doping configurations as the adsorption of F atoms on the surface significantly lowers the formation energy of the TiO2:Mn system. The magnetic moments of the Mn ions are reduced, whereas those of O atoms on the surface are increased. The magnetic moment of the O atoms is mainly derived from the spin polarization Px and Py orbitals. F adsorption promotes doping of Mn atoms and to a certain extent improves the stability of the structure, magnetism and metallicity.