Study On The Radiation Effect And Isotope Replacement Behavior Of ZrD_x Implanted By P/Ti Ions

As an important experimental platform for nuclear technology application,nuclear material research and neutron data measurement,deuterium-tritium(D-T)neutron generator is widely used in nuclear device development,material science,nuclear medicine and other fields.Zr T_x target film has become a candidate tritium target material because of excellent thermal stability and good hydrogen storage performance.However,the hydrogen isotope concentration and the microstructure of the target would be affected by the interaction of tritium target with D⁺,Ti⁺produced by ion source.This would lead to the reducing of the D-T neutron yield.Tritium is radioactive and very valuable.In this work,ZrD_x target film was used to replace the tritium target because of similar properties,and ZrD_x films were irradiated respectively with 150 ke V proton and 240 ke V Ti ions to simulate and study the impact of various ion beams on tritium target.On the research methods,the concentration change of main elements in the target film were measured by ion beam analysis.The surface morphology and microstructure changes of the samples were characterized by SEM,XRD and other methods,Thus,the influence and internal mechanism on the change of hydrogen isotope concentration and the irradiation damage in the target film are revealed with different ion beam irradiation.The main conclusions are as follows:1.Hydrogen isotope replacement and irradiation damage in ZrD_x thin films induced by proton irradiation.(1)At low fluence,H is distributed uniformly over the entire thickness of ZrD_xfilm.When the proton fluence is higher than 1×10¹⁷ protons/cm~2,the concentration of H is high and D concentration decreases sharply in this range of 600?750 nm,where corresponds to the severe damaged region.(2)With the increase of proton fluence,the average D/Zr atomic number ratio in ZrD_x films decreased from 1.51 to 1.39,while H/Zr increased to 0.626,indicating that H-D replacement occurs in the films.In this work,a theoretical model is proposed to reasonably describe the hydrogen isotope replacement observed in this experiment.(3)The displacement damage value is about 3.6 dpa when the fluence reached 1×10¹⁸ protons/cm~2.On the surface of ZrD_x,the circular exfoliation with diameter of about100?m and the exposed Si substrate are visible,and the surface roughness is the maximum.The analysis shows that it is caused by the diffusion and accumulating of a large amount of H to the Mo/Si boundary.(4)When the proton fluence is larger than 3×10¹⁷,some diffraction peaks almost disappear due to lattice distortion.But the implantation of 150ke V protons did not lead to the formation of new phases in ZrD_x.2.The effects of Ti ion implantation on deuterium concentration and microstructure in ZrD_x films.(1)Uneven pits can be observed on the surface due to the sputtering effect of titanium ions,and the surface roughness increases slightly after irradiation.(2)The implanted Ti shows a Gaussian distribution in the implanted region,and the position of average range is about 150 nm,which is basically consistent with the SRIM simulation results,indicating that the implanted Ti has hardly diffused..(3)In the depth of 25?200nm,the distribution of D is basically uniform,but the D concentration decreases after 200 nm,which was greater in the difference between the two regions with the increase of fluence.(4)In the implanted area,the concentration of Ti is positively correlated with the Ti ion fluence.The average D/Zr atomic ratio decreases from 1.77 to 1.6,which indicates that Ti ion irradiation caused the release of D in the irradiated region.(5)TiD_x,Ti and TiO₂ phase appeared in the sample when the fluence is higher than6×10¹⁶ ions/cm~2.Based on the above research results,the stability of ZrD_x film implanted by high dose p/Ti ions and hydrogen isotope replacement were systematically studied,which can provide reference for evaluating and improving the service life of ZrD_x/T_x target.