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Title: Vacancy effects on the formation of helium and krypton cavities in 3-C-SiC irradiated and annealed at elevated temperatures

Abstract

Polycrystalline 3C-SiC was sequentially irradiated at 400 and 750°C with 120 keV He 2+ and 4 MeV Kr 15+ ions to 10 17 and 41016 cm -2, respectively. The Kr 15+ ions penetrated the entire depth of the He 2+ ion implantation region. Three areas of He 2+, Kr 15+ and He 2+ + Kr 15+ ion implanted 3C-SiC were created through masked overlapping irradiations. The sample was subsequently annealed at 1600°C in vacuum and characterized using cross-sectional transmission electron microscopy and energy-dispersive x-ray spectroscopy. Compared to the He 2+ ion only implanted 3C-SiC, helium cavities in the He 2+ and Kr15+ co-implanted 3C-SiC had a smaller size but higher density. At 25 dpa, presence of He in the co-implanted 3C-SiC significantly promoted cavity growth; much smaller voids were formed in the Kr 15+ ion only irradiated 3C-SiC at the same dose. In addition, local Kr migration and trapping at cavities occurred, but long-range Kr diffusion in 3C-SiC was not observed up to 1600°C.

Authors:
; ; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1373853
Report Number(s):
PNNL-SA-124009
AT2030110
DOE Contract Number:
AC05-76RL01830
Resource Type:
Book
Resource Relation:
Related Information: Fusion Materials Semiannual Progress Report For Period Ending December 31, 2016, DOE-ER-0313/61:67-68
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE

Citation Formats

Zang, Hang, Liu, Wenbo, Li, Tao, He, Chaohui, Yun, Di, Jiang, Weilin, Devaraj, Arun, Edwards, Danny J., Henager, Charles H., Kurtz, Richard J., and Wang, Zhiguang. Vacancy effects on the formation of helium and krypton cavities in 3-C-SiC irradiated and annealed at elevated temperatures. United States: N. p., 2017. Web.
Zang, Hang, Liu, Wenbo, Li, Tao, He, Chaohui, Yun, Di, Jiang, Weilin, Devaraj, Arun, Edwards, Danny J., Henager, Charles H., Kurtz, Richard J., & Wang, Zhiguang. Vacancy effects on the formation of helium and krypton cavities in 3-C-SiC irradiated and annealed at elevated temperatures. United States.
Zang, Hang, Liu, Wenbo, Li, Tao, He, Chaohui, Yun, Di, Jiang, Weilin, Devaraj, Arun, Edwards, Danny J., Henager, Charles H., Kurtz, Richard J., and Wang, Zhiguang. Mon . "Vacancy effects on the formation of helium and krypton cavities in 3-C-SiC irradiated and annealed at elevated temperatures". United States. doi:.
@article{osti_1373853,
title = {Vacancy effects on the formation of helium and krypton cavities in 3-C-SiC irradiated and annealed at elevated temperatures},
author = {Zang, Hang and Liu, Wenbo and Li, Tao and He, Chaohui and Yun, Di and Jiang, Weilin and Devaraj, Arun and Edwards, Danny J. and Henager, Charles H. and Kurtz, Richard J. and Wang, Zhiguang},
abstractNote = {Polycrystalline 3C-SiC was sequentially irradiated at 400 and 750°C with 120 keV He2+ and 4 MeV Kr15+ ions to 1017 and 41016 cm-2, respectively. The Kr15+ ions penetrated the entire depth of the He2+ ion implantation region. Three areas of He2+, Kr15+ and He2+ + Kr15+ ion implanted 3C-SiC were created through masked overlapping irradiations. The sample was subsequently annealed at 1600°C in vacuum and characterized using cross-sectional transmission electron microscopy and energy-dispersive x-ray spectroscopy. Compared to the He2+ ion only implanted 3C-SiC, helium cavities in the He2+ and Kr15+ co-implanted 3C-SiC had a smaller size but higher density. At 25 dpa, presence of He in the co-implanted 3C-SiC significantly promoted cavity growth; much smaller voids were formed in the Kr15+ ion only irradiated 3C-SiC at the same dose. In addition, local Kr migration and trapping at cavities occurred, but long-range Kr diffusion in 3C-SiC was not observed up to 1600°C.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Feb 27 00:00:00 EST 2017},
month = {Mon Feb 27 00:00:00 EST 2017}
}

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  • Polycrystalline 3C-SiC was sequentially irradiated at 400 and 750°C with 120 keV He 2+ and 4 MeV Kr15+ ions to E21 and 4E20 ions/m2 with profiles of the implanted species peaked at 450 and 1500 nm, respectively. The masked overlapping irradiation created three study areas of He 2+, Kr 15+ and He 2+ + Kr 15+ implanted SiC. The doses at the depth of the peak He concentration in He 2+ and He 2+ + Kr 15+ implanted SiC correspond to 4 and 25 dpa. The sample was subsequently annealed at 1600°C for 3 h in vacuum and characterized usingmore » cross-sectional transmission electron microscopy and energy-dispersive x-ray spectroscopy. Compared to the He 2+ implanted SiC, He cavities show a smaller size and higher density in the co-implanted SiC. At 25 dpa, He presence in the co-implanted 3C-SiC significantly promotes He cavity growth, as contrasted to the smaller voids formed without He in the Kr 15+ irradiated SiC at the same dose. In addition, local Kr migration and trapping at cavities occur, but long-range Kr diffusion in SiC is not observed up to 1600°C.« less
  • Above room temperature, the accumulation of radiation damage in 3 C-SiC is strongly influenced by dynamic defect interaction processes and remains poorly understood. Here, we use a combination of ion channeling and transmission electron microscopy to study lattice disorder in 3 C-SiC irradiated with 500 keV Ar ions in the temperature range of 25–250 °C. Results reveal sigmoidal damage buildup for all the temperatures studied. For 150 °C and below, the damage level monotonically increases with ion dose up to amorphization. Starting at 200 °C, the shape of damage–depth profiles becomes anomalous, with the damage peak narrowing and moving tomore » larger depths and an additional shoulder forming close to the ion end of range. As a result, damage buildup curves for 200 and 250 °C exhibit an anomalous two-step shape, with a damage saturation stage followed by rapid amorphization above a critical ion dose, suggesting a nucleation-limited amorphization behavior. Despite their complexity, all damage buildup curves are well described by a phenomenological model based on an assumption of a linear dependence of the effective amorphization cross section on ion dose. Here, in contrast to the results of previous studies, 3 C-SiC can be amorphized by bombardment with 500 keV Ar ions even at 250 °C with a relatively large dose rate of ~2×10 13 cm -2 s -1, revealing a dominant role of defect interaction dynamics at elevated temperatures.« less
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  • We described positron annihilation spectroscopy characterization results for neutron-irradiated 3 C -SiC, with a specific focus on explaining the size and character of vacancy clusters as a complement to the current understanding of the neutron irradiation response of 3 C -SiC. Positron annihilation lifetime spectroscopy was used to capture the irradiation temperature and dose dependence of vacancy defects in 3 C -SiC following neutron irradiation from 0.01 to 31 dpa in the temperature range from 380C °to 790C .° The neutral and negatively charged vacancy clusters were identified and quantified. The results suggest that the vacancy defects that were measuredmore » by positron annihilation spectroscopy technique contribute very little to the transient swelling of SiC. Additionally, we used coincidence Doppler broadening measurement to investigate the chemical identity surrounding the positron trapping sites.Finally, we found that silicon vacancy-related defects dominate in the studied materials and the production of the antisite defect C Si may result in an increase in the probability of positron annihilation with silicon core electrons.« less