First-principles Study Of The Structure And Electronic Properties Of F-Doping Reduced CeO₂（111） Surface

The three-dimensional structure of CeO₂ is a face-centered cubic crystal,which belongs to the fluorite structure.Because of its high polishing efficiency and clean surface,it is widely used in cathode ray tube glass,optical glass,liquid crystal display,integrated circuits,photomasks and other polishing fields.However,pure CeO₂ has many defects,which hinders its wide application in various fields,and F atoms doped in the lattice of CeO₂ have smaller particles and reduce agglomeration.The element F in the polishing process is very important in rare earth polishing powders Role,and thus attract more attention.In order to further study the microstructure of the F-doped surface system,this paper will use the first-principle DFT+U method to calculate and analyze the unreduced and reduced（with different numbers of oxygen vacancies and different numbers of F before and after F doping）Atom)CeO₂（111）surface structure,electronic structure and oxygen vacancy formation energy,its details mainly include the following aspects:1.Establish and optimize CeO₂（111）surface model to obtain the optimal structure and lattice constant parameters.Optimizing CeO1.963（111）surface,CeO1.926（111）surface,CeO1.826（111）surface containing one,two,three oxygen vacancies to calculate their vacancy formation energy,comparing the oxygen vacancy formation energy in the three cases Calculate the electronic density,charge density,magnetic moment and Bader charge transfer of the stable structure,and compare with the unreduced CeO₂（111）surface system.2.Comparing the doping formation energies of four possible positions on the surface of CeO_1.963F_0.037（111）by calculation,determining the fluorine doping position,and selecting the lowest doping position.The surface structure,electronic state density,charge density,magnetic moment and Bader charge transfer of CeO_1.963F_0.037（111）F-doped unreduced system were calculated and compared with the unreduced CeO₂（111）surface system.3.Calculate CeO_1.926F_0.037（111）surface,CeO_1.889F_0.037（111）surface,CeO_1.852F_0.0379（111）surface containing one F atom and one,two,three oxygen vacancies F atoms and an oxygen vacancy on the surface of CeO_1,889F_0.074（111）.The oxygen vacancy formation energy on the surface of CeO_1.889F_0.07a（1 11）is analyzed.The oxygen vacancy formation energy in four cases is analyzed,and the stable reduction structure is determined.Moment and Bader charge transfer were compared with the unreduced CeO_1.963F_0.037（111）surface system.4.Calculate the adsorption energy and migration activation energy of 5 different highly symmetric positions of Ce and O single atoms on CeO₂（111）surface,CeO_1.963F_0.037（111）surface,CeO_1.963（111）surface and CeO_1.926F_0.037（111）surface,respectively,O single atom growth on three surfaces,the difficulty of diffusion.