Radiation Damage Simulation Of Rutile TiO₂ By Electron Beam,γ-ray And Fast Neutron

TiO₂ is a new type of third-generation wide band-gap semiconductor material.It has important application value in the fields of solar cells and photocatalysis.It is also one of the most promising nuclear materials for high-radioactive nuclear waste artificial rock-cured ceramics.In addition,TiO₂ also has outstanding magnetic properties and exhibits room temperature ferromagnetism in an un-doped state.It is a rare magnetic semiconductor material with great potential,and the source of room temperature ferromagnetism of TiO₂ has become one of the research hot-spots in materials science,spintronics and condensed matter physics in recent years.The doped and un-doped TiO₂have been reported to have room temperature ferromagnetism.The influence of doped magnetic particles（such as Fe,Co,Ni,Mn,etc.）to form magnetic secondary phases or intrinsic defects cannot be ruled out.The understanding of ferromagnetic sources is still divided.The development of particle irradiation technology in recent years has provided new ideas to explore its magnetic source.However,It is hard to experimentally obtain the process of particle irradiation materials,the evolution of defects and the radiation damage,therefore,multi-scale simulation is needed to gain corresponding data results.The research on radiation damage of materials has been widely used in the fields of material property modification,structural material design,reactor research,national defense security,aerospace and other fields.Generally,the average displacement per atom is used to measure the radiation damage.In order to better study the important application of radiation in the field of materials,it is important to accurately calculate the damage caused by particles to the materials.In this paper,electron,γ-rays and neutron are used to study the radiation damage of rutile TiO₂,and the main work and results are summarized as follows:Using the interaction of electrons with Ti and O atoms in rutile TiO₂,the minimum electron energy required to form O defects is 123.54 keV,and the corresponding Ti atom is 830.78 keV.Furthermore,MCNP software was used to simulate the transport process of 0.1¹ MeV electron beam in the 10×10×0.5 mm³ rutile TiO₂ sample and the corresponding formula was used to calculate the radiation damage.The displacement per atom（dpa）in the sample under 1 MeV electron irradiation was calculated.It is found that the damage area is concentrated between 0.25 and 0.5 mm,and the dpa of electrons to Ti atoms,O atoms and TiO₂ under different energies are calculated which lay the foundation for the later experiments.In order to calculate theγ-ray's radiation damage in the rutile TiO₂,firstly,the displacement damage cross sections of the three kinds of reactions of photoelectric effect,compton effect and electronic effect which are common toγ-ray and matter are first given,andγ-ray is mainly considered in the calculation.Dislocation damage to materials caused by the interaction of electrons with atoms.First,MCNP was used to simulate the electron flux spectrum characteristics of 1¹0 MeVγ-rays when irradiating a sample of 10×10×1 mm³ rutile.With the increase of energy,the number of positrons gradually increased.The two-dimensional distribution of the dpa of rutile samples by radiation can be found.The damage is mainly concentrated on the surface,which is convenient for experimental phenomenon interpretation and later experiments.At the same time,the dpa sizes of electrons and positrons in the sample at different energies are given.In addition,our group carried out the influence of ⁶⁰Co source irradiation on rutile on its magnetic and optical characteristics,and systematically gave the irradiated damage of ⁶⁰Co source to rutile samples from the aspect of simulation calculation.At the same time,combined with experimental data,it was found that the main existence of oxygen defects is in accordance with theoretical calculations.The fast neutron irradiated rutile TiO₂ was used to calculate the radiation damage.The energy transfer relationship during the two-body collision and the formula for the loss of energy were studied.The nuclear data processing software NJOY2016 was used to give the displacement damage of the Ti and O atoms.The cross-section and the point-by-point interpolation correction method were used to obtain the displacement damage cross section of TiO₂.Combined with MCNP to simulate the neutron transport process of neutrons in the rutile sample,the neutrons on Ti,O and rutile at Am-Be source,D-D source and D-T source were given the dpa size of TiO₂.At the same time,a preliminary version of the radiation damage calculation software was developed,which filled a gap for the development of the domestic radiation damage calculation field.