We report on cavity swelling at peak damage regions of three ferritic-martensitic(FM)steels(NHS,RAFM and T91)irradiated by 196 MeV Kr ions at different temperatures(450/550℃).Cavity configurations of the irradiated s...We report on cavity swelling at peak damage regions of three ferritic-martensitic(FM)steels(NHS,RAFM and T91)irradiated by 196 MeV Kr ions at different temperatures(450/550℃).Cavity configurations of the irradiated specimens are investigated by transmission electron microscopy with cross-section technique.For home-made reduced activation ferritic-martensitic(RAFM)and T91 steels irradiated at 450℃,both large size and bimodal size distribution of the cavity are found in their peak damage regions,whereas novel high silicon(NHS)steel exhibits good swelling resistance at different irradiation temperatures.Temperature relativity of the cavity swelling in NHS,RAFM and T91 steels is discussed briefly.展开更多
The effects of 100 keV H-ion implantation on the structure of LiTaO3 crystal are investigated by Raman and UV/VIS/NIR spectroscopies.The implantation fluence is in the range from 1.0 × 10^(13) to 1.0 × 10^(1...The effects of 100 keV H-ion implantation on the structure of LiTaO3 crystal are investigated by Raman and UV/VIS/NIR spectroscopies.The implantation fluence is in the range from 1.0 × 10^(13) to 1.0 × 10^(17) H^(+)/cm^(2).The experimental results show the dependence of the crystal structure on ion fluence.It is found that the structural modification of the LiTaO3 crystal is due to two processes.One is H-ions occupying lithium vacancies (VLi),which is predominant at a fluence less than 1.0 × 10^(14) H^(+) /cm^(2).This process causes the reduction of negative charge centers in the crystal and relaxation of distortion in the local lattice structure.The other is the influence of defects created during implantation,which plays a dominant role gradually in the structural modification at a fluence larger than 1.0 × 10^(15) H^(+)/cm^(2).展开更多
Radiation-induced defect annealing in He<sup>+</sup> ion-implanted 4H-SiC via H<sup>+</sup> ion irradiation is investigated by Raman spectroscopy. There are 4H-SiC wafers irradiated with 230 ke...Radiation-induced defect annealing in He<sup>+</sup> ion-implanted 4H-SiC via H<sup>+</sup> ion irradiation is investigated by Raman spectroscopy. There are 4H-SiC wafers irradiated with 230 keV He<sup>+</sup> ions with fluences ranging from cm<sup>−2</sup> to cm<sup>−2</sup> at room temperature. The post-implantation samples are irradiated by 260 keV H<sup>+</sup> ions at a fluence of cm<sup>−2</sup> at room temperature. The intensities of Raman lines decrease after He implantation, while they increase after H irradiation. The experimental results present that the magnitude of Raman line increment is related to the concentration of pre-existing defects formed by He implantation. A strong new peak located near 966 cm<sup>−1</sup>, which is assigned to 3C-SiC LO () phonon, is found in the He-implanted sample with a fluence of cm<sup>−2</sup> followed by H irradiation. However, for the He-implanted sample with a fluence of cm<sup>−2</sup> followed by H irradiation, no 3C-SiC phonon vibrations are found. The detailed reason for H irradiation-induced phase transformation in the He-implanted 4H-SiC is discussed.展开更多
The influence of strain field on defect formation energy and threshold displacement energy （Ed） in body-centered cubic tungsten （W） is studied with molecular dynamics simulation. Two different W potentials （Fikar...The influence of strain field on defect formation energy and threshold displacement energy （Ed） in body-centered cubic tungsten （W） is studied with molecular dynamics simulation. Two different W potentials （Fikar and Juslin） are compared and the results indicate that the connection distance and selected function linking the short-range and long-range portions of the potentials affect the threshold displacement energy and its direction-specific values. The minimum Ed direction calculated with the Fikar potential is （100） and with the Juslin potential is （111）. Nevertheless, the most stable seff-interstitial configuration is found to be a （111）-crowdion for both the potentials. This stable configuration does not change with the applied strain. Varying the strain from compression to tension increases the vacancy formation energy while decreases the self-interstitial formation energy. The formation energy of a seff-interstitial changes more significantly than a vacancy such that Ed decreases with the applied hydrostatic strain from compression to tension.展开更多
Different mass percent polyacrylonitrile （PAN）-polyethylene oxide （PEO） gels were prepared and irradiated by an electron beam （EB） with energy of 1.0 MeV to the dose ranging from 13 kGy to 260 kGy. The gels were...Different mass percent polyacrylonitrile （PAN）-polyethylene oxide （PEO） gels were prepared and irradiated by an electron beam （EB） with energy of 1.0 MeV to the dose ranging from 13 kGy to 260 kGy. The gels were analysed by using Fourier transform infrared spectrum, gel fraction and ionic conductivity （IC） measurement. The results show that the gel is crosslinked by EB irradiation, the crosslinking degree rises with the increasing EB irradiation dose （ID） and the mass percents of both PAN and PEO contribute a lot to the crosslinking; in addition, EB irradiation can promote the IC of PAN-PEO gels. There exists an optimum irradiation dose, at which the IC can increase dramatically. The IC changes of the PAN-PEO gels along with ID are divided into three regions： IC rapidly increasing region, IC decreasing region and IC balanced region. The cause of the change can be ascribed to two aspects, gel capturing electron degree and crosslinking degree. By comparing the IC-ID curves of different mass percents of PAN and PEO in gel, we found that PAN plays a more important role for gel IC promotion than PEO, since addition of PAN in gel causes the IC-ID curve sharper, while addition of PEO in gel causes the curve milder.展开更多
The structural modification of C60 films induced by 300-keV Xe-ion irradiation was investigated. The irradiated C60 films were analysed using Fourier transform infrared spectroscopy, the Raman scattering technique, ul...The structural modification of C60 films induced by 300-keV Xe-ion irradiation was investigated. The irradiated C60 films were analysed using Fourier transform infrared spectroscopy, the Raman scattering technique, ultraviolet/visible spectrophotometry and atomic force microscopy. The analysis results indicate that the Xe-ion irradiation induces polymerization and damage of the C60 molecule and significantly modifies the surface morphology and the optical property of the C60 films. The damage cross-section for the C60 molecule was also evaluated.展开更多
Amorphous silicon （a-Si）, nanocrystalline silicon （nc-Si） and hydrogenated nanocrys- talline silicon （nc-Si：H） films were fabricated by using chemical vapor deposition （CVD） system. The a-Si and nc-Si thin fi...Amorphous silicon （a-Si）, nanocrystalline silicon （nc-Si） and hydrogenated nanocrys- talline silicon （nc-Si：H） films were fabricated by using chemical vapor deposition （CVD） system. The a-Si and nc-Si thin films were irradiated with 94 MeV Xe-ions at fluences of 1.0 × 10^11 ions/cm2, 1.0 × 10^12 ions/cm^2 and 1.0 × 10^13 ions/era2 at room temperature （RT）. The nc-Si：H films were irradiated with 9 MeV Xe-ions at 1.0 ×10^12 Xe/cm^2, 1.0 × 10^13 Xe/cm2 and 1.0×10^14 Xe/cm2 at RT. For comparison, mono-crystalline silicon （c-Si） samples were also irradiated at RT with 94 MeV Xe-ions. All samples were analyzed by using an UV/VIS/NIR spectrometer and an X-ray powder diffractometer. Variations of the optical band-gap （Eg） and grain size （D） versus the irradiation fluence were investigated systematically. The obtained results showed that the optical band-gaps and grain size of the thin films changed dramatically whereas no observable change was found in c-Si samples after Xe-ion irradiation. Possible mechanism underlying the modification of silicon thin films was briefly discussed.展开更多
Modified novel high silicon steel （MNHS, a newly developed reduced-activation martensitic alloy） and commercial alloy Tgl are implanted with 200 keV He2＋ ions to a dose of 5 × 1020 ions/m2 at 300, 450 and 560~...Modified novel high silicon steel （MNHS, a newly developed reduced-activation martensitic alloy） and commercial alloy Tgl are implanted with 200 keV He2＋ ions to a dose of 5 × 1020 ions/m2 at 300, 450 and 560~C. Transmission electron microscopy （TEM） is used to characterize the size and morphology of He bubbles. With the increase of the implantation temperature, TEM observations indicate that bubbles increase in size and the proportion of ＇brick shaped＇ cuboid bubbles increases while the proportion of polyhedral bubbles decreases in both the steel samples. For the samples implanted at the same temperature, the average size of He bubbles in MNHS is smaller than that in T91. This might be due to the abundance of boundaries and precipitates in MNHS, which provide additional sites for the trapping of He atoms, thus reduce the susceptibility of MNHS to He embrittlement.展开更多
Ternary M_(n+1)AX_(n) phase,where M stands for an early transition metal,A is an A-group element,and X is either C or N,has exhibited the combination properties of ceramics and metals.Their excellent performance leads...Ternary M_(n+1)AX_(n) phase,where M stands for an early transition metal,A is an A-group element,and X is either C or N,has exhibited the combination properties of ceramics and metals.Their excellent performance leads them to be a very promising candidate for applications involving extremely harsh nuclear environments,acting as a candidate pump impeller and bearing materials for lead cooled fast reactor,and fuel pellet coatings and accident tolerant fuel coatings(ATFCs).展开更多
Ti_(3)AlC_(2)samples are irradiated in advance by 3.5 MeV Fe-ion to the fluence of 1.0×10^(16)ion/cm^(2),and then are implanted by 500 keV He-ion with the fluence of 1.0×10^(17)ion/cm^(2)at room temperature....Ti_(3)AlC_(2)samples are irradiated in advance by 3.5 MeV Fe-ion to the fluence of 1.0×10^(16)ion/cm^(2),and then are implanted by 500 keV He-ion with the fluence of 1.0×10^(17)ion/cm^(2)at room temperature.The irradiated samples are investigated by grazing incidence x-ray diffraction(GIXRD)and transmission electron microscopy(TEM).GIXRD results show serious structural distortion,but without amorphization in the irradiated samples.Fe-ion irradiation and He-ion implantation create much more serious structural distortion than single Fe-ion irradiation.TEM results reveal that there are a large number of defect clusters in the damage region,and dense spherical He bubbles appear in the He depositional region.It seems that the pre-damage does not influence the growth of He bubbles,but He-ion implantation influences the pre-created defect configurations.展开更多
As recombination centers of vacancies(Vs)and self-interstitial atoms(SIAs),firstly grain boundaries(GBs)should have strong capability of trapping point defects.In this study,abilities to trap Vs and SIAs of eight symm...As recombination centers of vacancies(Vs)and self-interstitial atoms(SIAs),firstly grain boundaries(GBs)should have strong capability of trapping point defects.In this study,abilities to trap Vs and SIAs of eight symmetric tilt GBs in tungsten are investigated through first-principles calculations.展开更多
基金Supported by the National Basic Research Program of China under Grant No 2010CB832902the National Natural Science Foundation of China under Grant Nos 91026002,91126011 and 11275005。
文摘We report on cavity swelling at peak damage regions of three ferritic-martensitic(FM)steels(NHS,RAFM and T91)irradiated by 196 MeV Kr ions at different temperatures(450/550℃).Cavity configurations of the irradiated specimens are investigated by transmission electron microscopy with cross-section technique.For home-made reduced activation ferritic-martensitic(RAFM)and T91 steels irradiated at 450℃,both large size and bimodal size distribution of the cavity are found in their peak damage regions,whereas novel high silicon(NHS)steel exhibits good swelling resistance at different irradiation temperatures.Temperature relativity of the cavity swelling in NHS,RAFM and T91 steels is discussed briefly.
基金Supported by the National Basic Research Program of China under Grant No 2010CB832902the National Natural Science Foundation of China(10835010)the Chinese Academy of Sciences.
文摘The effects of 100 keV H-ion implantation on the structure of LiTaO3 crystal are investigated by Raman and UV/VIS/NIR spectroscopies.The implantation fluence is in the range from 1.0 × 10^(13) to 1.0 × 10^(17) H^(+)/cm^(2).The experimental results show the dependence of the crystal structure on ion fluence.It is found that the structural modification of the LiTaO3 crystal is due to two processes.One is H-ions occupying lithium vacancies (VLi),which is predominant at a fluence less than 1.0 × 10^(14) H^(+) /cm^(2).This process causes the reduction of negative charge centers in the crystal and relaxation of distortion in the local lattice structure.The other is the influence of defects created during implantation,which plays a dominant role gradually in the structural modification at a fluence larger than 1.0 × 10^(15) H^(+)/cm^(2).
基金Supported by the National Natural Science Foundation of China under Grant Nos 11005130,11475229 and 91026002the Strategic Priority Research Program of Chinese Academy of Sciences under Grant No XDA03010301
文摘Radiation-induced defect annealing in He<sup>+</sup> ion-implanted 4H-SiC via H<sup>+</sup> ion irradiation is investigated by Raman spectroscopy. There are 4H-SiC wafers irradiated with 230 keV He<sup>+</sup> ions with fluences ranging from cm<sup>−2</sup> to cm<sup>−2</sup> at room temperature. The post-implantation samples are irradiated by 260 keV H<sup>+</sup> ions at a fluence of cm<sup>−2</sup> at room temperature. The intensities of Raman lines decrease after He implantation, while they increase after H irradiation. The experimental results present that the magnitude of Raman line increment is related to the concentration of pre-existing defects formed by He implantation. A strong new peak located near 966 cm<sup>−1</sup>, which is assigned to 3C-SiC LO () phonon, is found in the He-implanted sample with a fluence of cm<sup>−2</sup> followed by H irradiation. However, for the He-implanted sample with a fluence of cm<sup>−2</sup> followed by H irradiation, no 3C-SiC phonon vibrations are found. The detailed reason for H irradiation-induced phase transformation in the He-implanted 4H-SiC is discussed.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11375242,91026002,91426301 and 11405231the Strategic Priority Research Program of the Chinese Academy of Sciences under Grant No XDA03010301the support of the Office of Fusion Energy Sciences,U.S.Department of Energy under Contract DE-AC05-76RL01830
文摘The influence of strain field on defect formation energy and threshold displacement energy （Ed） in body-centered cubic tungsten （W） is studied with molecular dynamics simulation. Two different W potentials （Fikar and Juslin） are compared and the results indicate that the connection distance and selected function linking the short-range and long-range portions of the potentials affect the threshold displacement energy and its direction-specific values. The minimum Ed direction calculated with the Fikar potential is （100） and with the Juslin potential is （111）. Nevertheless, the most stable seff-interstitial configuration is found to be a （111）-crowdion for both the potentials. This stable configuration does not change with the applied strain. Varying the strain from compression to tension increases the vacancy formation energy while decreases the self-interstitial formation energy. The formation energy of a seff-interstitial changes more significantly than a vacancy such that Ed decreases with the applied hydrostatic strain from compression to tension.
基金Project supported by the National Basic Research Program of China (Grant No.2010CB832902)the Key Program of the National Natural Science Foundation of China (Grant No.10835010)the Main Direction Program of Knowledge Innovation of Chinese Academy of Sciences (Grant No.KJCX2-YW-N35)
文摘Different mass percent polyacrylonitrile （PAN）-polyethylene oxide （PEO） gels were prepared and irradiated by an electron beam （EB） with energy of 1.0 MeV to the dose ranging from 13 kGy to 260 kGy. The gels were analysed by using Fourier transform infrared spectrum, gel fraction and ionic conductivity （IC） measurement. The results show that the gel is crosslinked by EB irradiation, the crosslinking degree rises with the increasing EB irradiation dose （ID） and the mass percents of both PAN and PEO contribute a lot to the crosslinking; in addition, EB irradiation can promote the IC of PAN-PEO gels. There exists an optimum irradiation dose, at which the IC can increase dramatically. The IC changes of the PAN-PEO gels along with ID are divided into three regions： IC rapidly increasing region, IC decreasing region and IC balanced region. The cause of the change can be ascribed to two aspects, gel capturing electron degree and crosslinking degree. By comparing the IC-ID curves of different mass percents of PAN and PEO in gel, we found that PAN plays a more important role for gel IC promotion than PEO, since addition of PAN in gel causes the IC-ID curve sharper, while addition of PEO in gel causes the curve milder.
基金Project supported by the Key Program of the National Natural Science Foundation of China (Grant No.10835010)the National Natural Science Foundation of China (Grant Nos.10675150 and 10175084)the National Basic Research Program of China (Grant No.2010CB832902)
文摘The structural modification of C60 films induced by 300-keV Xe-ion irradiation was investigated. The irradiated C60 films were analysed using Fourier transform infrared spectroscopy, the Raman scattering technique, ultraviolet/visible spectrophotometry and atomic force microscopy. The analysis results indicate that the Xe-ion irradiation induces polymerization and damage of the C60 molecule and significantly modifies the surface morphology and the optical property of the C60 films. The damage cross-section for the C60 molecule was also evaluated.
基金supported by the Major State Basic Research Development Program of China(973Program,No.2010CB832902)the Knowledge Innovation Program of the Chinese Academy of Sciences(No.KJCX2-YW-N35)
文摘Amorphous silicon （a-Si）, nanocrystalline silicon （nc-Si） and hydrogenated nanocrys- talline silicon （nc-Si：H） films were fabricated by using chemical vapor deposition （CVD） system. The a-Si and nc-Si thin films were irradiated with 94 MeV Xe-ions at fluences of 1.0 × 10^11 ions/cm2, 1.0 × 10^12 ions/cm^2 and 1.0 × 10^13 ions/era2 at room temperature （RT）. The nc-Si：H films were irradiated with 9 MeV Xe-ions at 1.0 ×10^12 Xe/cm^2, 1.0 × 10^13 Xe/cm2 and 1.0×10^14 Xe/cm2 at RT. For comparison, mono-crystalline silicon （c-Si） samples were also irradiated at RT with 94 MeV Xe-ions. All samples were analyzed by using an UV/VIS/NIR spectrometer and an X-ray powder diffractometer. Variations of the optical band-gap （Eg） and grain size （D） versus the irradiation fluence were investigated systematically. The obtained results showed that the optical band-gaps and grain size of the thin films changed dramatically whereas no observable change was found in c-Si samples after Xe-ion irradiation. Possible mechanism underlying the modification of silicon thin films was briefly discussed.
基金Supported by the National Basic Research Program of China under Grant Nos 2010CB832902 and 91026002the National Natural Science Foundation of China under Grant No U1232121
文摘Modified novel high silicon steel （MNHS, a newly developed reduced-activation martensitic alloy） and commercial alloy Tgl are implanted with 200 keV He2＋ ions to a dose of 5 × 1020 ions/m2 at 300, 450 and 560~C. Transmission electron microscopy （TEM） is used to characterize the size and morphology of He bubbles. With the increase of the implantation temperature, TEM observations indicate that bubbles increase in size and the proportion of ＇brick shaped＇ cuboid bubbles increases while the proportion of polyhedral bubbles decreases in both the steel samples. For the samples implanted at the same temperature, the average size of He bubbles in MNHS is smaller than that in T91. This might be due to the abundance of boundaries and precipitates in MNHS, which provide additional sites for the trapping of He atoms, thus reduce the susceptibility of MNHS to He embrittlement.
文摘Ternary M_(n+1)AX_(n) phase,where M stands for an early transition metal,A is an A-group element,and X is either C or N,has exhibited the combination properties of ceramics and metals.Their excellent performance leads them to be a very promising candidate for applications involving extremely harsh nuclear environments,acting as a candidate pump impeller and bearing materials for lead cooled fast reactor,and fuel pellet coatings and accident tolerant fuel coatings(ATFCs).
基金Supported by the National Natural Science Foundation of China under Grant Nos 11405231 and 91426301
文摘Ti_(3)AlC_(2)samples are irradiated in advance by 3.5 MeV Fe-ion to the fluence of 1.0×10^(16)ion/cm^(2),and then are implanted by 500 keV He-ion with the fluence of 1.0×10^(17)ion/cm^(2)at room temperature.The irradiated samples are investigated by grazing incidence x-ray diffraction(GIXRD)and transmission electron microscopy(TEM).GIXRD results show serious structural distortion,but without amorphization in the irradiated samples.Fe-ion irradiation and He-ion implantation create much more serious structural distortion than single Fe-ion irradiation.TEM results reveal that there are a large number of defect clusters in the damage region,and dense spherical He bubbles appear in the He depositional region.It seems that the pre-damage does not influence the growth of He bubbles,but He-ion implantation influences the pre-created defect configurations.
基金Supported by the National Natural Science Foundation of China under Grant Nos 91426301,11605256 and 11405231
文摘As recombination centers of vacancies(Vs)and self-interstitial atoms(SIAs),firstly grain boundaries(GBs)should have strong capability of trapping point defects.In this study,abilities to trap Vs and SIAs of eight symmetric tilt GBs in tungsten are investigated through first-principles calculations.
