We investigated the effect of grain boundary structures on the trapping strength of HeN（N is the number of helium atoms） defects in the grain boundaries of nickel. The results suggest that the binding energy of an i...We investigated the effect of grain boundary structures on the trapping strength of HeN（N is the number of helium atoms） defects in the grain boundaries of nickel. The results suggest that the binding energy of an interstitial helium atom to the grain boundary plane is the strongest among all sites around the plane. The He_N defect is much more stable in nickel bulk than in the grain boundary plane. Besides, the binding energy of an interstitial helium atom to a vacancy is stronger than that to a grain boundary plane. The binding strength between the grain boundary and the HeN defect increases with the defect size. Moreover, the binding strength of the HeN defect to the Σ3（112）[110] grain boundary becomes much weaker than that to other grain boundaries as the defect size increases.展开更多
The clustering behavior of helium atoms in thorium dioxide has been investigated by first-principles calculations. The results show that He atoms tend to form a cluster around an octahedral interstitial site（OIS）. A...The clustering behavior of helium atoms in thorium dioxide has been investigated by first-principles calculations. The results show that He atoms tend to form a cluster around an octahedral interstitial site（OIS）. As the concentration of He atoms in ThO2 increases, the strain induced by the He atoms increases and the octahedral interstitial site is not large enough to accommodate a large cluster, such as a He hexamer. We considered three different Schottky defect（SD） configurations（SD1, SD2, and SD3）. When He atoms are located in the SD sites, the strain induced by the He atoms is released and the incorporation and binding energies decrease. The He trimer is the most stable cluster in SD1. Large He clusters, such as a He hexamer, are also stable in the SDs.展开更多
Electrically active defects in the phosphor-doped single-crystal silicon, induced by helium-ion irradiation under thermal annealing, have been investigated. Isothermal charge-sensitive deep-level transient spectroscop...Electrically active defects in the phosphor-doped single-crystal silicon, induced by helium-ion irradiation under thermal annealing, have been investigated. Isothermal charge-sensitive deep-level transient spectroscopy was employed to study the activation energy and capture cross-section of helium-induced defects in silicon samples. It was shown that the activation energy levels produced by helium-ion irradiation first increased with increasing annealing temperature, with the maximum value of the activation energy occurring at 873 K, and reduced with further increase of the annealing temperature. The energy levels of defects in the samples annealed at 873 and 1073 K are found to be located near the mid-forbidden energy gap level so that they can act as thermally stable carrier recombination centres.展开更多
One of the serious concerns for tungsten materials in fusion devices is the radiation defects caused by helium plasma irradiation since helium is a fusion product. The fiber-formed nanostructure is thought to have a p...One of the serious concerns for tungsten materials in fusion devices is the radiation defects caused by helium plasma irradiation since helium is a fusion product. The fiber-formed nanostructure is thought to have a possible weakness against the plasma heat flux on the plasma- facing component and also may destroy the reflectivity of optical mirrors. In this paper an inter- esting method for the recovery of such tungsten surfaces is shown. The recovery process depends on the grade and manufacturing process of tungsten materials.展开更多
基金Project supported by the Program of International S&T Cooperation,China(Grant No.2014DFG60230)the National Basic Research Program of China(Grant No.2010CB934504)+2 种基金Strategically Leading Program of the Chinese Academy of Sciences(Grant No.XDA02040100)the Shanghai Municipal Science and Technology Commission,China(Grant No.13ZR1448000)the National Natural Science Foundation of China(Grant Nos.91326105 and 21306220)
文摘We investigated the effect of grain boundary structures on the trapping strength of HeN（N is the number of helium atoms） defects in the grain boundaries of nickel. The results suggest that the binding energy of an interstitial helium atom to the grain boundary plane is the strongest among all sites around the plane. The He_N defect is much more stable in nickel bulk than in the grain boundary plane. Besides, the binding energy of an interstitial helium atom to a vacancy is stronger than that to a grain boundary plane. The binding strength between the grain boundary and the HeN defect increases with the defect size. Moreover, the binding strength of the HeN defect to the Σ3（112）[110] grain boundary becomes much weaker than that to other grain boundaries as the defect size increases.
基金Project supported by the Program of International S&T Cooperation,China(Grant No.2014DFG60230)the National Natural Science Foundation of China(Grant Nos.11605273,21571185,U1404111,11504089,21501189,and 21676291)+1 种基金the Shanghai Municipal Science and Technology Commission,China(Grant No.16ZR1443100)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA02040104)
文摘The clustering behavior of helium atoms in thorium dioxide has been investigated by first-principles calculations. The results show that He atoms tend to form a cluster around an octahedral interstitial site（OIS）. As the concentration of He atoms in ThO2 increases, the strain induced by the He atoms increases and the octahedral interstitial site is not large enough to accommodate a large cluster, such as a He hexamer. We considered three different Schottky defect（SD） configurations（SD1, SD2, and SD3）. When He atoms are located in the SD sites, the strain induced by the He atoms is released and the incorporation and binding energies decrease. The He trimer is the most stable cluster in SD1. Large He clusters, such as a He hexamer, are also stable in the SDs.
基金Project supported by the National Natural Science Foundation of China (Grant No 10575124)
文摘Electrically active defects in the phosphor-doped single-crystal silicon, induced by helium-ion irradiation under thermal annealing, have been investigated. Isothermal charge-sensitive deep-level transient spectroscopy was employed to study the activation energy and capture cross-section of helium-induced defects in silicon samples. It was shown that the activation energy levels produced by helium-ion irradiation first increased with increasing annealing temperature, with the maximum value of the activation energy occurring at 873 K, and reduced with further increase of the annealing temperature. The energy levels of defects in the samples annealed at 873 and 1073 K are found to be located near the mid-forbidden energy gap level so that they can act as thermally stable carrier recombination centres.
基金supported by a Grant-in-aid for scientific Research (B) (20360414) from JSPS
文摘One of the serious concerns for tungsten materials in fusion devices is the radiation defects caused by helium plasma irradiation since helium is a fusion product. The fiber-formed nanostructure is thought to have a possible weakness against the plasma heat flux on the plasma- facing component and also may destroy the reflectivity of optical mirrors. In this paper an inter- esting method for the recovery of such tungsten surfaces is shown. The recovery process depends on the grade and manufacturing process of tungsten materials.
