Positron annihilation study of defect formation and evolution in matrix graphite under He ion irradiation  

作　　者：Hong-Xia Xu Jian-Dang Liu Bang-Jiao Ye Zi-Wen Pan Jun Lin Jin-Liang Song Jian-Qing Cao Chao Yan Ying-Ping Hao Jin-Xing Cheng Qing-Bo Wang 

机构地区：[1]Shanghai Institute of Applied Physics,Chinese Academy of Sciences,Shanghai 201800,China [2]State Key Laboratory of Particle Detection and Electronics,University of Science and Technology of China,Hefei 230026,China [3]Ruijin Hospital Affiliated to Shanghai Jiao Tong University School of Medicine,Shanghai 200025,China [4]Beijing Institute of High Technology,Beijing 100094,China

出　　处：《Nuclear Science and Techniques》2025年第1期13-21,共9页核技术(英文)

基　　金：supported by the National Natural Science Foundation of China(Nos.12005289,52072397);State Key Laboratory of Nuclear Detection and Electronics,University of Science and Technology of China(SKLPDE-KF-202316).

摘　　要：The stability of matrix graphite under neutron irradiation and in corrosive environments is crucial for the safe operation of molten salt reactors(MSRs).Raman spectroscopy and a slow positron beam were employed to investigate the effects of He ion irradiation fluences and subsequent annealing on the microstructure and defects of the matrix graphite.He ions with 500 keV energy and fluences ranging from 1.1×10^(15)ions∕cm^(2)to 3.5×10^(17)ions∕cm^(2)were used to simulate neutron irradiation at 300 K.The samples with an irradiation fluence of 3.5×10^(16)ions∕cm^(2)were subjected to isochronal annealing at different temperatures(573 K,873 K and 1173 K)for 3 h.The Raman results revealed that the D peak gradually increased,whereas the intrinsic G peak decreased with increasing irradiation fluence.At the same irradiation fluence,the D peak gradually decreased,whereas the intrinsic G peak increased with increasing annealing temperature.Slow positron beam analysis demonstrated that the density or size of irradiation defects(vacancy type)increased with higher irradiation fluence,but decreased rapidly with increasing annealing temperature.The Raman spectral analysis of sample cross sections subjected to high irradiation fluences revealed the emergence of amorphization precisely at the depth where ion damage was most pronounced,whereas the surface retained its crystalline structure.Raman and positron annihilation analyses indicated that the matrix graphite exhibited good irradiation resistance to He ions at 300 K.However,vacancy-type defects induced by He ion irradiation exhibit poor thermal stability and can be easily removed during annealing.

关 键 词：GRAPHITE Positron annihilation IRRADIATION Raman spectrum 

分 类 号：TL341[核科学技术—核技术及应用]