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    Thermal desorption characteristic of helium ion irradiated nickel-base alloy
    Shasha Lv(吕沙沙), Rui Zhu(朱睿), Yumeng Zhao(赵雨梦), Mingyang Li(李明阳), Guojing Wang(王国景), Menglin Qiu(仇猛淋), Bin Liao(廖斌), Qingsong Hua(华青松), Jianping Cheng(程建平), Zhengcao Li(李正操)
    Chin. Phys. B, 2020, 29 (4): 040704.   DOI: 10.1088/1674-1056/ab7e99
    Abstract727)   HTML    PDF (856KB)(140)      
    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 HenVm 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.
    Developing cold-resistant high-adhesive electronic substrate for WIMPs detectors at CDEX
    Yuanyuan Liu(刘圆圆), Jianping Cheng(程建平), Pan Pang(庞盼), Bin Liao(廖斌), Bin Wu(吴彬), Minju Ying(英敏菊), Fengshou Zhang(张丰收), Lin Chen(陈琳), Shasha Lv(吕沙沙), Yandong Liu(刘言东), Tianxi Sun(孙天希)
    Chin. Phys. B, 2020, 29 (4): 045203.   DOI: 10.1088/1674-1056/ab718a
    Abstract624)   HTML    PDF (2908KB)(170)      
    Herein we report a prototypical electronic substrate specifically designed to serve the weakly interacting massive particles (WIMPs) detectors at the China Dark Matter Experiment (CDEX). Because the bulky high-purity germanium (HPGe) detectors operate under liquid-nitrogen temperatures and ultralow radiation backgrounds, the desired electronic substrates must maintain high adhesivity across different layers in such cold environment and be free from any radioactive nuclides. To conquer these challenges, for the first time, we employed polytetrafluoroethylene ((C2F4)n) foil as the base substrate, in conjunction with ion implantation and deposition techniques using an independently developed device at Beijing Normal University for surface modification prior to electroplating. The remarkable peeling strengths of 0.88±0.06 N/mm for as-prepared sample and 0.75±0.05 N/mm for that after 2.5-days of soaking inside the liquid nitrogen were observed, while the regular standards commonly require 0.4 N/mm~ 0.6 N/mm for electronic substrates.
    In situ luminescence measurement of 6H-SiC at low temperature
    Meng-Lin Qiu(仇猛淋), Peng Yin(殷鹏), Guang-Fu Wang(王广甫), Ji-Gao Song(宋纪高), Chang-Wei Luo(罗长维), Ting-Shun Wang(王庭顺), Guo-Qiang Zhao(赵国强), Sha-Sha Lv(吕沙沙), Feng-Shou Zhang(张丰收), Bin Liao(廖斌)
    Chin. Phys. B, 2020, 29 (4): 046106.   DOI: 10.1088/1674-1056/ab7804
    Abstract839)   HTML    PDF (1479KB)(159)      
    To understand the evolution of defects in SiC during irradiation and the influence of temperature, in situ luminescence measurements of 6H-SiC crystal samples were carried out by ion beam induced luminescence (IBIL) measurement under 2 MeV H+ at 100 K, 150 K, 200 K, 250 K, and 300 K. A wide band (400-1000 nm) was found in the spectra at all temperatures, and the intensity of the IBIL spectra was highest at 150 K among the five temperatures. A small peak from 400 nm to 500 nm was only observed at 100 K, related with the D1 defect as a donor-acceptor pair (D-A) recombination. For further understanding the luminescent centers and their evolution, the orange band (1.79 eV) and the green band (2.14 eV) in the energy spectrum were analyzed by Gaussian decomposition, maybe due to the donor-deep defect/conduction band-deep defect transitions and Ti related bound excition, respectively. Finally, a single exponential fit showed that when the temperature exceeded 150 K, the two luminescence centers' resistance to radiation was reduced.
    Experimental and computational study of visible light-induced photocatalytic ability of nitrogen ions-implanted TiO2 nanotubes
    Ruijing Zhang(张瑞菁), Xiaoli Liu(刘晓丽), Xinggang Hou(侯兴刚), Bin Liao(廖斌)
    Chin. Phys. B, 2020, 29 (4): 048501.   DOI: 10.1088/1674-1056/ab6d53
    Abstract658)   HTML    PDF (2011KB)(183)      
    Nitrogen-doped TiO2 nanotubes (TNTs) were prepared by ion implantation and anodic oxidation. The prepared samples were applied in photocatalytic (PC) oxidation of methyl blue, rhodamine B, and bisphenol A under light irradiation. To explore the influence of doped ions on the band and electronic structure of TiO2, computer simulations were performed using the VASP code implementing spin-polarized density functional theory (DFT). Both substitutional and interstitial nitrogen atoms were considered. The experimental and computational results propose that the electronic structure of TiO2 was modified because of the emergence of impurity states in the band gap by introducing nitrogen into the lattice, leading to the absorption of visible light. The synergy effects of tubular structures and doped nitrogen ions were responsible for highly efficient and stable PC activities induced by visible and ultraviolet (UV) light.
ISSN 1674-1056   CN 11-5639/O4

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