Thermal desorption characteristic of helium ion irradiated nickel-base alloy

The nickel-base alloy is one of the leading candidate materials for generation IV nuclear reactor pressure vessel.To evaluate its stability of helium damage and retention,helium ions with different energy of 80 keV and 180 keV were introduced by ion implantation to a certain dose(peak displacement damage 1-10 dpa).Then thermal desorption spectroscopy(TDS)of helium atoms was performed to discuss the helium desorption characteristic and trapping sites.The desorption peaks shift to a lower temperature with increasing dpa for both 80 keV and 180 keV irradiation,reflecting the reduced diffusion activation energy and faster diffusion within the alloy.The main release peak temperature of 180 keV helium injection is relatively higher than that of 80 keV at the same influence,which is because the irradiation damage of 180 keV,helium formation and entrapment occur deeper.The broadening of the spectra corresponds to different helium trapping sites(He-vacancies,grain boundary)and desorption mechanisms(different Hen Vm size).The helium retention amount of 80 keV is lower than that of 180 keV,and a saturation limit associated with the irradiation of 80 keV has been reached.The relatively low helium retention proves the better resistance to helium bubbles formation and helium brittleness.     

利用离子激发发光研究低温条件下ZnO发光行为EI北大核心CSCD

离子激发发光(Ions beam induced luminescence,IBIL)可以实时原位分析不同温度、不同离子辐照条件下材料内部点缺陷的演变行为。本文利用2 MeV H^(+)研究了300,200,100 K温度下ZnO单晶内部点缺陷发光及其随注量的演变行为。实验中发现ZnO深能级发射和近带边发射,结合Voigt分峰与XPS实验结果,确定红光(1.75 eV)与V_(Zn)相关,橙红光(1.95 eV)来自Zn_(i)到O_(i)跃迁;对于与V_(O)相关的绿光(2.10 eV),其红移可能由于温度降低导致更多电子由导带释放到Zn_(i)。峰中心位于3.10 eV和3.20 eV近带边发射分别来自于Zn_(i)到价带的跃迁和激子复合,红移原因分别为Zn_(i)附近局域化能级和带隙收缩。利用单指数公式对发光强度进行拟合,获得的衰减速率常数(f)可以表征缺陷的辐射硬度,对比发现深能级发射峰在200 K时辐射硬度最大,而近带边发射峰在300 K时辐射硬度最大。