Additively manufactured stainless steel exhibits different oxidation and corrosion properties compared with traditional counterparts.Molecular dynamics simulations were performed to systematically investigate Cr diffu...Additively manufactured stainless steel exhibits different oxidation and corrosion properties compared with traditional counterparts.Molecular dynamics simulations were performed to systematically investigate Cr diffusion near nanopores,in order to elucidate the fast formation of dense oxidation layers in laser powder bed fusion processed 304L stainless steel after ion irradiation.The influence of pore diameter and temperature on Cr diffusion was studied in Fe simulation boxes with 1 at.%Cr and random nanometric pores.The results show that the existence of nanopores significantly accelerates Cr diffusion,facilitating the formation of oxide layers.While increasing with temperature,the diffusion coefficient does not increase uniformly with pore diameter.Regarding the nanopores with diameters of 4.82-13.25Å,the diffusion coefficient of Cr in their vicinity is maximized at diameter of about 6Å.The specific fast diffusion paths near the nanopores were exposed and discussed.展开更多
In this letter,we demonstrate the effect ofγirradiation on the lateral AlGaN/GaN Schottky barrier diodes(SBDs)with self-terminated recessed anode structure and low work-function metal tungsten(W)as anode.For a compre...In this letter,we demonstrate the effect ofγirradiation on the lateral AlGaN/GaN Schottky barrier diodes(SBDs)with self-terminated recessed anode structure and low work-function metal tungsten(W)as anode.For a comprehensive evaluation of the radiation-resistance performance of the device,the total dose ofγirradiation is up to 100 kGy with irradiation time of 20 h.Attributed to the barrier lowering effect of the W/GaN interface induced byγirradiation observed in the experiment,the extracted turnon voltage(VON)defined at anode forward current of 1 mA decreases from 0.47 to 0.43 V.Meanwhile,benefiting from the reinforced Schottky interface treated by post-anode-annealing,a high breakdown voltage(BV)of 1.75 kV is obtained for theγ-irradiated AlGaN/GaN SBD,which shows the promising application for the deep-space radiation environment and promotes the development of radiation-resistance research for GaN SBDs.展开更多
The features of optical defects in a chemical vapor deposition (CVD) synthetic type Ⅱ a diamond were characterized using photoluminescence (PL) spectroscopy, before and after electron irradiation. The sample was cut ...The features of optical defects in a chemical vapor deposition (CVD) synthetic type Ⅱ a diamond were characterized using photoluminescence (PL) spectroscopy, before and after electron irradiation. The sample was cut within a {100} growth layer, and irradiated with 2 MeV electrons along the <100> axis. PL spectra of sample were collected under 532 nm and 355 nm laser excitation, at room temperature and 77 K, and linear scanning analysis along incident depth was applied to determine the distribution of defects. The pre-irradiation characterization results revealed uniformly distributed PL centers at 389 nm, 469 nm, 533 nm, 575 nm (ZPL of NV 0), 637 nm (ZPL of NV -), and 736.7/737.1 nm (ZPL doublet of SiV -). After irradiation, the differential responses of these as-grown defects were observed, alongside the emergence of irradiation-induced defects, namely 489 nm center, H3 center (ZPL at 504 nm) and GR1 center (ZPL at 741 nm). The maximum penetration depth of 2 MeV electron-irradiation induced defects was determined to be 2.1 mm. This work primarily presents the depth profiles of both as-grown and irradiation-induced defects in 2 MeV electrons irradiated diamond. The result provides experimental data for better understanding of the radiation effect in diamonds. Serving as a reference for diamond enhancement by electron irradiation.展开更多
Investigating the influence of radiation on glass fibre composites is essential for their use in space and aerospace environment.Gaining insight into the damage mechanisms caused by gamma irradiation,can improve the s...Investigating the influence of radiation on glass fibre composites is essential for their use in space and aerospace environment.Gaining insight into the damage mechanisms caused by gamma irradiation,can improve the safety and resilience of structures.This paper is aimed at investigating the failure mode and damage of gamma-irradiated repurposed pultruded glass fibre-reinforced polyester subjected to lowvelocity impact using three types of non-destructive techniques.Three sets of differently layered configurations(CRC,WCRW,W2CR2C)consisting of chopped(c),roving(r),and weaved(w)fibre-reinforced polyester are applied in this study.Drop hammer test is applied to evaluate the low-impact resistance properties of Gamma-irradiated composite at 100 kGy,500 kGy,and 1000 kGy.Preliminary flexural and hardness tests are conducted to further assess the behaviour of irradiated polymer composites.Further,the damage modes associated with the low-impact test are characterised using infrared thermography,flat panel digital radiography,and microscope observation.The results show that the composites irradiated with various doses display good impact resistance at 20 J,presenting minor damages in the form of dents on the surface.The irradiated CRC and WCRW display best impact resistance at 500 kGy,while W2CR2C at 1000 kGy.This shows that the layering sequence of reinforcement fibre can influence the impact resistance of irradiated composites.Apart from that,the application of non-destructive techniques show different damage mechanisms in the form resin cracks,yarn splitting/fracture,and matrix splitting when the composites are exposed at high and low irradiation doses.These findings offer valuable data for the defence industry,particularly in the areas of repair,maintenance,and the development of new materials.展开更多
In-situ TEM observation was conducted during Ni^(+)&He^(+)dual-beam irradiation to monitor the evolution of dislocation loops accompanied by He bubbles in the Ni-based alloy GH3535.Two distinct evolutions of dislo...In-situ TEM observation was conducted during Ni^(+)&He^(+)dual-beam irradiation to monitor the evolution of dislocation loops accompanied by He bubbles in the Ni-based alloy GH3535.Two distinct evolutions of dislocation loops,driven by residual stresses,were observed within the monitored grains.Hence,molec-ular dynamics(MD)simulations were employed to reveal the effects of stress magnitude and direction on loop evolution,including size,number density,type and variation.The simulations revealed that the presence of compressive stress reduced the formation energy of perfect dislocation loops,thus promoting their formation.Stress state was found to influence the preferential orientation of the loops,and com-pressive stress resulted in a decreased number density of dislocation loops but an increase in their size.This establishes a clear relationship between stress state and magnitude and the evolution of dislocation loops during ion beam irradiation.Additionally,the nature and characteristics of dislocation loops were quantified to explore the effects of He concentrations on their evolution.The higher He concentration not only promotes the nucleation of dislocation loops,leading to their higher number density,but also facil-itates the unfaulting evolution by increasing the stacking fault energy(SFE).Moreover,the accumulation of He in the lower-He-concentration sample led to the growth of dislocation loops in multiple stages,explaining their nearly identical average sizes when compared to the higher-He-concentration sample.展开更多
Influences of swift heavy ion(SHI)irradiation induced defects on electronic properties of the bulk SnSe_(2)based FETs are explored.Latent tracks and amounts of Se vacancies in the irradiated SnSe_(2)were confirmed.Red...Influences of swift heavy ion(SHI)irradiation induced defects on electronic properties of the bulk SnSe_(2)based FETs are explored.Latent tracks and amounts of Se vacancies in the irradiated SnSe_(2)were confirmed.Red shift of the A1g peak indicates that the resonance frequency of the phonons is reduced due to the defect generation in SnSe_(2).The source–drain current Ids increased at ion fluence of 1×10^(10)ions·cm^(-2),which was attributeded to the irradiation caused Se vacancies,which hence increases the concentration of conduction electrons.The carrier mobility was about 16.9 cm^(2)·V^(-1)·s^(-1)for the devices irradiated at ion fluence of 1×10^(9)ions·cm^(-2),which benefited from heavy ion irradiation enhanced interlayer coupling.The mechanism of device performance optimization after irradiation is discussed in detail.This work provides evidence that,given the electronic properties of two-dimensional material-based device,vacancies and interlayer coupling effects caused by SHI irradiation should not be ignored.展开更多
Ultra High Molecular Weight Polyethylene(UHMWPE)has been widely used as a bearing material for artificial joint replacement over forty years.It is usually crosslinked by gamma rays irradiation before its implantation ...Ultra High Molecular Weight Polyethylene(UHMWPE)has been widely used as a bearing material for artificial joint replacement over forty years.It is usually crosslinked by gamma rays irradiation before its implantation into human body.In this study,UHMWPE and UHMWPE/nano-hydroxyapatite(n-HA)composite were prepared by vacuum hot-pressing method.The prepared materials were irradiated by gamma rays in vacuum and molten heat treated in vacuum just after irradiation.The effect of filling n-HA with gamma irradiation on tribological properties of UHMWPE was investigated by using friction and wear experimental machine(model MM-200)under deionized water lubrication.Micro-morphology of worn surface was observed by metallographic microscope.Contact angle and hardness of the materials were also measured.The results show that contact angle and hardness are changed by filling n-HA and gamma irradiation.Friction coefficient and wear rate under deionized water lubrication are reduced by filling n-HA.While friction coefficient is increased and wear rate is reduced significantly by gamma irradiation.The worn surface of unfilled material is mainly characterized as adhesive wear and abrasive wear,and that of n-HA filled material is mainly characterized as abrasive wear.After gamma irradiation,the degrees of adhesive and abrasive wear for unfilled material and abrasive wear of n-HA filled material are significantly reduced.Unfilled and filled materials after irradiation are mainly shown as slight fatigue wear.The results indicate that UHMWPE and UHMWPE/n-HA irradiated at the dose of 150 kGy can be used as bearing materials in artificial joints for its excellent wear resistance compared to original UHMWPE.展开更多
[Objective] The aim was to provide reference for research on radiation and breeding of cotton pollen through irradiating common ripe pollen grain of upland cotton by 60Co-γ Ray of varied doses. [Method] Ripe pollen g...[Objective] The aim was to provide reference for research on radiation and breeding of cotton pollen through irradiating common ripe pollen grain of upland cotton by 60Co-γ Ray of varied doses. [Method] Ripe pollen grains of upland cotton were irradiated by 60Co-γ Ray with doses of 5, 10, 15, and 20 Gy, respectively, to learn radiation effect and select appropriate dose. [Result] Most properties of M1 obviously showed variation when dose was over 10 Gy; vitality, growth, and fertility were greatly inhibited when dose was 15 Gy which was almost semi-lethal concentration, and variation species were richest at the same time, which provided materi- als for practical breeding. [Conclusion] 60Co-γ Ray of 15 Gy is more suitable for mutagenesis research on ripe pollen grains of upland cotton.展开更多
In this work,the high-energy-density plasmas(HEDP)evolved from joule-class-femtosecond-laser-irradiated nanowire-array(NWA)targets were numerically and experimentally studied.The results of particle-in-cell simulation...In this work,the high-energy-density plasmas(HEDP)evolved from joule-class-femtosecond-laser-irradiated nanowire-array(NWA)targets were numerically and experimentally studied.The results of particle-in-cell simulations indicate that ions accelerated in the sheath field around the surfaces of the nanowires are eventually confined in a plasma,contributing most to the high energy densities.The protons emitted from the front surfaces of the NWA targets provide rich information about the interactions that occur.We give the electron and ion energy densities for broad target parameter ranges.The ion energy densities from NWA targets were found to be an order of magnitude higher than those from planar targets,and the volume of the HEDP was several-fold greater.At optimal target parameters,8%of the laser energy can be converted to confined protons,and this results in ion energy densities at the GJ/cm^(3) level.In the experiments,the measured energy of the emitted protons reached 4 MeV,and the changes in energy with the NWA’s parameters were found to fit the simulation results well.Experimental measurements of neutrons from 2H(d,n)3He fusion with a yield of(24±18)×10^(6)/J from deuterated polyethylene NWA targets also confirmed these results.展开更多
In order to discuss the mechanisms of permanent fixation of wood compression set , compressed wood of Chinese fir (Cunninghamia lanceolata) was irradiated by gamma rays from 60 Co. The irradiation doses wer...In order to discuss the mechanisms of permanent fixation of wood compression set , compressed wood of Chinese fir (Cunninghamia lanceolata) was irradiated by gamma rays from 60 Co. The irradiation doses were 0 (for match specim ens), 10 3, 5×10 3, 10 4, 5×10 4, 10 5, 5×10 5, 10 6, 5×10 6 Gy, res pectively. Then the weight loss, the equilibrium moisture content (EMC), the rec overy of wood compression set after adsorption (RSA) and the recovery after imme rsion in water (RSW), as well as the creep behaviour under a dry specimen condit ion and under an adsorption and subsequent desorption condition were measured an d discussed. This research proves that the doses of gamma irradiation have great effect on weight loss, EMC, RSA, RSW of irradiated compressed wood of Chinese f ir. The weight loss and the EMC increase, the RSA and the RSW fall drastically w hen the irradiation doses exceed 10 6 Gy. Both the instantaneous compliance and the creep compliance of the irradiated specimens under the two measurement cond itions show the general trend of increase with the increase of gamma irradiation doses. It can be deduced that decomposition or decrystallization reactions happ en in the wood cell wall at high gamma irradiation doses, especially at doses of around 5×10 6 Gy. In addition, this research proves that decomposition of mai n components of cell wall of compressed wood will lead to fixation of compressio n set of wood to a certain degree.展开更多
Using L-glutathione(GSH)as a capping agent,Zn Se/GSH quantum dots(QDs)were prepared under microwave irradiation and irradiated under dark,ultraviolet light and incandescent light,respectively.The properties and intera...Using L-glutathione(GSH)as a capping agent,Zn Se/GSH quantum dots(QDs)were prepared under microwave irradiation and irradiated under dark,ultraviolet light and incandescent light,respectively.The properties and interaction of different lights irradiated ZnSe/GSH QDs and bovine serum albumin(BSA)were studied systematically.The fluorescence(FL)spectra results reveal that the quenching mechanism are all the static quenching in nature.The quenching constant(Ksv)and binding constant(K)value of different irradiated Zn Se/GSH QDs and BSA all increased with the change of light types from dark to incandescent light and UV light.The number of binding site(n)is close to 1 at different temperatures.The lighting types influence the enthalpy and entropy changes.The Fourier transform infrared(FTIR)spectra indicate that the light induced GSH ligand will facilitate photocatalytic oxidation on the surface of ZnSe/GSH QDs.The circular dichroism(CD)results show that theα-helicity content of BSA decreases from 60.34%,59.31%,to 58.79%under UV lighting,incandescent lighting and dark conditions.The interaction results of different lights illuminated ZnSe/GSH QDs with BSA by CD spectra method matches well with that by FL and FTIR spectra.That is,the interaction of ZnSe/GSH QDs and BSA from strong to weak is UV light,incandescent light and dark in sequence.展开更多
The influence of total dose irradiation on hot-carrier reliability of 65 nm n-type metal-oxide-semiconductor field- effect transistors （nMOSFETs） is investigated. Experimental results show that hot-carrier degradati...The influence of total dose irradiation on hot-carrier reliability of 65 nm n-type metal-oxide-semiconductor field- effect transistors （nMOSFETs） is investigated. Experimental results show that hot-carrier degradations on ir- radiated narrow channel nMOSFETs are greater than those without irradiation. The reason is attributed to radiation-induced charge trapping in shallow trench isolation （STI）. The electric field in the pinch-off region of the nMOSFET is enhanced by radiation-induced charge trapping in STI, resulting in a more severe hot-carrier effect.展开更多
The ionoluminescence （IL） spectra of a ZnO single crystal irradiated with 2.5？MeV H＋＋ ions reveal that its intensity decreases with increasing the ion fluence, which indicates that the concentration of luminescen...The ionoluminescence （IL） spectra of a ZnO single crystal irradiated with 2.5？MeV H＋＋ ions reveal that its intensity decreases with increasing the ion fluence, which indicates that the concentration of luminescence centers decreases with irradiation. The Gaussian decomposition results of the ZnO IL spectrum with a fluence of 1.77×10^11ions/cm^2 show that the spectrum is a superposition of energy levels centered at 1.75eV, 2.10eV, 3.12eV and 3.20eV. The four peaks are associated with electronic transitions from CB to VZnZn, CB to Oii, Znii to VB and the decay of self-trapped excitons, respectively. The results of single-exponential fitting demonstrate that different luminescent centers have different radiation resistance, which may explain why the emission decreases more slowly in the NBE band than in the DBE band. The agglomeration of larger point clusters accounts for the decrease in the concentration of luminescence centers and the increase in the concentration of non-luminescence centers, which indicates that the defect clusters induced by ion implantation act as nonradiative recombination centers and suppress light emission. The results of the photoluminescence spectra of a virgin ZnO single crystal and a ZnO single crystal irradiated with a fluence of 3.4××10^14ions/cm^2 show that compared with the virgin ZnO, the emission intensity of irradiated ZnO decreases by nearly two orders of magnitude, which demonstrates that the irradiation effect reduces radiative recombination and enhances nonradiative recombination. The conclusions of photoluminescence are consistent with the IL results.展开更多
Photoluminescence(PL)bands from potassium dihydrogen phosphate(KDP)crystals are studied by time-resolved PL spectroscopy.KDPcrystals irradiated at a laser fluence of 11.5 J/cm^(2) are found to have the highest probabi...Photoluminescence(PL)bands from potassium dihydrogen phosphate(KDP)crystals are studied by time-resolved PL spectroscopy.KDPcrystals irradiated at a laser fluence of 11.5 J/cm^(2) are found to have the highest probability of phosphorus–oxygen hole center defects and the lowest probability of phosphorus-oxygen electric center defects,in contrast to the probabilities of these defects forKDPcrystals irradiated at 9.0 J/cm^(2).The probabilities of these two defects occurring in retired components are found to be intermediate between those for crystals irradiated at the two different fluences.The two types of defects may result fromtwo differentmechanisms and may interconvert under certain conditions.Thus,there are differences between the defects in KDP crystals irradiated at a high laser fluence and those in retired components.展开更多
Positron lifetime spectrum was measured and the change of the free volume was studied for commercial polyethylene (PE) and polytetrafluoroethylene (PTFE) during 7-irradiation processing up to 265 kGy. The free volume ...Positron lifetime spectrum was measured and the change of the free volume was studied for commercial polyethylene (PE) and polytetrafluoroethylene (PTFE) during 7-irradiation processing up to 265 kGy. The free volume size increases but the crystallinity decreases as irradiation dose increases in PE. Both qualities (free volume size and crystallinity) in PTFE display an opposite behavior. The fractional free volume reduces monotonically with increasing irradiation dose in both PE and PTFE. The competition between the crosslinkmg and the splitting decomposition in polymers can be used to understand the free volume changes with irradiation dose.展开更多
An improved indirect scheme for laser positron generation is proposed. The positron yields in high-ZZ metal targets irradiated by laser produced electrons from near-critical density plasmas and underdense plasma are i...An improved indirect scheme for laser positron generation is proposed. The positron yields in high-ZZ metal targets irradiated by laser produced electrons from near-critical density plasmas and underdense plasma are investigated numerically. It is found that the positron yield is mainly affected by the number of electrons of energies up to several hundreds of MeV. Using near-critical density targets for electron acceleration, the number of high energy electrons can be increased dramatically. Through start-to-end simulations, it is shown that up to 6.78×10106.78×1010 positrons can be generated with state-of-the-art Joule-class femtosecond laser systems.展开更多
We investigated the effect of treatment temperature on the magnetic property of iron nitride foils irradiated with nitrogen plasma. The iron nitride foils irradiated with nitrogen plasma were composed of ε-Fe2/3N, γ...We investigated the effect of treatment temperature on the magnetic property of iron nitride foils irradiated with nitrogen plasma. The iron nitride foils irradiated with nitrogen plasma were composed of ε-Fe2/3N, γ'-Fe4N and γ nitrogen austenite in α-Fe of the matrix. The saturation magnetization of the iron nitride foils decreased with increasing the surface temperature. The coercive force of the iron nitride foils increased with increasing the surface temperature.展开更多
Blue colored topaz is one of the most recognized gemstones worldwide.However,it is rarely found in the field and the products have been made mostly in laboratory using gamma,neutron and electron irradiation or combina...Blue colored topaz is one of the most recognized gemstones worldwide.However,it is rarely found in the field and the products have been made mostly in laboratory using gamma,neutron and electron irradiation or combinations of these devices.Origin of the blue color in topaz remains not well understood, largely due to a lack of nondestructive way in idnetifying the blue topaz.Here we report a compari-展开更多
We theoretically study the dependence of photoelectron angular distribution on laser polarization direction in nitrogen molecules. The approach is based on the time-dependent density functional theory at the level of ...We theoretically study the dependence of photoelectron angular distribution on laser polarization direction in nitrogen molecules. The approach is based on the time-dependent density functional theory at the level of local density approximation complemented by self-interaction correction. It is found that photoelectron emission in one photon regime could be considered as a probing tool for the main character of different types of molecular orbitals （σ or π）. The pattern of emitted photoelectrons strongly depends on the polarized angle of the laser, for σ orbital, the number of photoelectron decreases with increasing the polarized angle, while for π orbital, it has the inverse relation to the polarized angle, which reveals the multi-electron effect in molecules. On the other hand, concerning the total photoelectron emission, one should take into account a few occupied orbitals instead of only the outmost one.展开更多
The magnetism of highly oriented pyrolytic graphite （HOPG） induced by ion implantation is investigated with electron spin resonance （ESR） spectroscopy and magnetization measurements. The results indicate that the ...The magnetism of highly oriented pyrolytic graphite （HOPG） induced by ion implantation is investigated with electron spin resonance （ESR） spectroscopy and magnetization measurements. The results indicate that the ESR spectra of the HOPG sample correlate with ion species, incident energy and dose of implantation. The correlation of the ESR spectra and magnetism of the HOPG sample with ：2C＋ ion implantation and H＋ ion implantation are studied in detail. The ferromagnetism of the HOPG sample is likely related to the asymmetric L1 line, which may be attributed to the interaction between localized defects and itinerant electrons occupied in the ＇impurity＇ band induced by ion implantation.展开更多
基金financial support of National Natural Science Foundation of China(Nos.U2241245,52073176 and U22B2067)Natural Science Foundation of Shenyang(No.23-503-6-05)Shanghai Engineering Research Center of High-Performance Medical Device Materials(No.20DZ2255500).
文摘Additively manufactured stainless steel exhibits different oxidation and corrosion properties compared with traditional counterparts.Molecular dynamics simulations were performed to systematically investigate Cr diffusion near nanopores,in order to elucidate the fast formation of dense oxidation layers in laser powder bed fusion processed 304L stainless steel after ion irradiation.The influence of pore diameter and temperature on Cr diffusion was studied in Fe simulation boxes with 1 at.%Cr and random nanometric pores.The results show that the existence of nanopores significantly accelerates Cr diffusion,facilitating the formation of oxide layers.While increasing with temperature,the diffusion coefficient does not increase uniformly with pore diameter.Regarding the nanopores with diameters of 4.82-13.25Å,the diffusion coefficient of Cr in their vicinity is maximized at diameter of about 6Å.The specific fast diffusion paths near the nanopores were exposed and discussed.
基金supported in part by the Key Research and Development Projects of Shaanxi Province(Grant No.2024GX-YBXM-082)in part by the Natural Science Basic Research Program of Shaanxi Province(Grant No.2023-JC-JQ-56)+2 种基金in part by the Fundamental Research Funds for the Central Universities(Grant Nos.QTZX23076,XJSJ25014)in part by the funding of the National Key Research and Development Program of China(Grant No.2022YFB3604400)in part by the China Postdoctoral Science Foundation(Grant No.2021TQ0256).
文摘In this letter,we demonstrate the effect ofγirradiation on the lateral AlGaN/GaN Schottky barrier diodes(SBDs)with self-terminated recessed anode structure and low work-function metal tungsten(W)as anode.For a comprehensive evaluation of the radiation-resistance performance of the device,the total dose ofγirradiation is up to 100 kGy with irradiation time of 20 h.Attributed to the barrier lowering effect of the W/GaN interface induced byγirradiation observed in the experiment,the extracted turnon voltage(VON)defined at anode forward current of 1 mA decreases from 0.47 to 0.43 V.Meanwhile,benefiting from the reinforced Schottky interface treated by post-anode-annealing,a high breakdown voltage(BV)of 1.75 kV is obtained for theγ-irradiated AlGaN/GaN SBD,which shows the promising application for the deep-space radiation environment and promotes the development of radiation-resistance research for GaN SBDs.
基金This work is supported by National Natural Science Foundation of China(No.42372054)。
文摘The features of optical defects in a chemical vapor deposition (CVD) synthetic type Ⅱ a diamond were characterized using photoluminescence (PL) spectroscopy, before and after electron irradiation. The sample was cut within a {100} growth layer, and irradiated with 2 MeV electrons along the <100> axis. PL spectra of sample were collected under 532 nm and 355 nm laser excitation, at room temperature and 77 K, and linear scanning analysis along incident depth was applied to determine the distribution of defects. The pre-irradiation characterization results revealed uniformly distributed PL centers at 389 nm, 469 nm, 533 nm, 575 nm (ZPL of NV 0), 637 nm (ZPL of NV -), and 736.7/737.1 nm (ZPL doublet of SiV -). After irradiation, the differential responses of these as-grown defects were observed, alongside the emergence of irradiation-induced defects, namely 489 nm center, H3 center (ZPL at 504 nm) and GR1 center (ZPL at 741 nm). The maximum penetration depth of 2 MeV electron-irradiation induced defects was determined to be 2.1 mm. This work primarily presents the depth profiles of both as-grown and irradiation-induced defects in 2 MeV electrons irradiated diamond. The result provides experimental data for better understanding of the radiation effect in diamonds. Serving as a reference for diamond enhancement by electron irradiation.
基金funded by Universiti Tenaga Nasional(UNITEN),Malaysia for supporting this research under the Dato'Low Tuck Kwong International Grant,project code 20238002DLTKsupport for this work from the Ministry of Higher EducationMalaysia through the Higher Institution Center of Excellence(HICoE 2023-JPT(BPKI)1000/016/018/34(5))program+2 种基金supported by Tenaga Nasional Berhad(TNB)and UNITEN through the BOLD Refresh Postdoctoral Fellowships under Grant J510050002-IC-6 BOLDREFRESH2023-Centre of ExcellencePrince Sultan University for their supportIndustrial Technology Division,Malaysian Nuclear Agency for their support in this research work.
文摘Investigating the influence of radiation on glass fibre composites is essential for their use in space and aerospace environment.Gaining insight into the damage mechanisms caused by gamma irradiation,can improve the safety and resilience of structures.This paper is aimed at investigating the failure mode and damage of gamma-irradiated repurposed pultruded glass fibre-reinforced polyester subjected to lowvelocity impact using three types of non-destructive techniques.Three sets of differently layered configurations(CRC,WCRW,W2CR2C)consisting of chopped(c),roving(r),and weaved(w)fibre-reinforced polyester are applied in this study.Drop hammer test is applied to evaluate the low-impact resistance properties of Gamma-irradiated composite at 100 kGy,500 kGy,and 1000 kGy.Preliminary flexural and hardness tests are conducted to further assess the behaviour of irradiated polymer composites.Further,the damage modes associated with the low-impact test are characterised using infrared thermography,flat panel digital radiography,and microscope observation.The results show that the composites irradiated with various doses display good impact resistance at 20 J,presenting minor damages in the form of dents on the surface.The irradiated CRC and WCRW display best impact resistance at 500 kGy,while W2CR2C at 1000 kGy.This shows that the layering sequence of reinforcement fibre can influence the impact resistance of irradiated composites.Apart from that,the application of non-destructive techniques show different damage mechanisms in the form resin cracks,yarn splitting/fracture,and matrix splitting when the composites are exposed at high and low irradiation doses.These findings offer valuable data for the defence industry,particularly in the areas of repair,maintenance,and the development of new materials.
基金supported by the National Natural Science Foundation of China(Nos.U2341261 and 12375280)the Young Potential Program of Shanghai Institute of Applied Physics,Chinese Academy of Sciences(No.YXJH-2022002)the National MCF Energy R&D Program(No.2022YFE03110000).
文摘In-situ TEM observation was conducted during Ni^(+)&He^(+)dual-beam irradiation to monitor the evolution of dislocation loops accompanied by He bubbles in the Ni-based alloy GH3535.Two distinct evolutions of dislocation loops,driven by residual stresses,were observed within the monitored grains.Hence,molec-ular dynamics(MD)simulations were employed to reveal the effects of stress magnitude and direction on loop evolution,including size,number density,type and variation.The simulations revealed that the presence of compressive stress reduced the formation energy of perfect dislocation loops,thus promoting their formation.Stress state was found to influence the preferential orientation of the loops,and com-pressive stress resulted in a decreased number density of dislocation loops but an increase in their size.This establishes a clear relationship between stress state and magnitude and the evolution of dislocation loops during ion beam irradiation.Additionally,the nature and characteristics of dislocation loops were quantified to explore the effects of He concentrations on their evolution.The higher He concentration not only promotes the nucleation of dislocation loops,leading to their higher number density,but also facil-itates the unfaulting evolution by increasing the stacking fault energy(SFE).Moreover,the accumulation of He in the lower-He-concentration sample led to the growth of dislocation loops in multiple stages,explaining their nearly identical average sizes when compared to the higher-He-concentration sample.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12375261,12175287,12205350,and 62234013)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(Grant No.2022424).
文摘Influences of swift heavy ion(SHI)irradiation induced defects on electronic properties of the bulk SnSe_(2)based FETs are explored.Latent tracks and amounts of Se vacancies in the irradiated SnSe_(2)were confirmed.Red shift of the A1g peak indicates that the resonance frequency of the phonons is reduced due to the defect generation in SnSe_(2).The source–drain current Ids increased at ion fluence of 1×10^(10)ions·cm^(-2),which was attributeded to the irradiation caused Se vacancies,which hence increases the concentration of conduction electrons.The carrier mobility was about 16.9 cm^(2)·V^(-1)·s^(-1)for the devices irradiated at ion fluence of 1×10^(9)ions·cm^(-2),which benefited from heavy ion irradiation enhanced interlayer coupling.The mechanism of device performance optimization after irradiation is discussed in detail.This work provides evidence that,given the electronic properties of two-dimensional material-based device,vacancies and interlayer coupling effects caused by SHI irradiation should not be ignored.
基金supported by the National Natural Science Foundation of China (Grant No. 50575106)High Technology Project of Jiangsu Province, P. R. China (Grant No. BG2007046)
文摘Ultra High Molecular Weight Polyethylene(UHMWPE)has been widely used as a bearing material for artificial joint replacement over forty years.It is usually crosslinked by gamma rays irradiation before its implantation into human body.In this study,UHMWPE and UHMWPE/nano-hydroxyapatite(n-HA)composite were prepared by vacuum hot-pressing method.The prepared materials were irradiated by gamma rays in vacuum and molten heat treated in vacuum just after irradiation.The effect of filling n-HA with gamma irradiation on tribological properties of UHMWPE was investigated by using friction and wear experimental machine(model MM-200)under deionized water lubrication.Micro-morphology of worn surface was observed by metallographic microscope.Contact angle and hardness of the materials were also measured.The results show that contact angle and hardness are changed by filling n-HA and gamma irradiation.Friction coefficient and wear rate under deionized water lubrication are reduced by filling n-HA.While friction coefficient is increased and wear rate is reduced significantly by gamma irradiation.The worn surface of unfilled material is mainly characterized as adhesive wear and abrasive wear,and that of n-HA filled material is mainly characterized as abrasive wear.After gamma irradiation,the degrees of adhesive and abrasive wear for unfilled material and abrasive wear of n-HA filled material are significantly reduced.Unfilled and filled materials after irradiation are mainly shown as slight fatigue wear.The results indicate that UHMWPE and UHMWPE/n-HA irradiated at the dose of 150 kGy can be used as bearing materials in artificial joints for its excellent wear resistance compared to original UHMWPE.
基金Supported by National Natural Science Foundation of China (10475041)~~
文摘[Objective] The aim was to provide reference for research on radiation and breeding of cotton pollen through irradiating common ripe pollen grain of upland cotton by 60Co-γ Ray of varied doses. [Method] Ripe pollen grains of upland cotton were irradiated by 60Co-γ Ray with doses of 5, 10, 15, and 20 Gy, respectively, to learn radiation effect and select appropriate dose. [Result] Most properties of M1 obviously showed variation when dose was over 10 Gy; vitality, growth, and fertility were greatly inhibited when dose was 15 Gy which was almost semi-lethal concentration, and variation species were richest at the same time, which provided materi- als for practical breeding. [Conclusion] 60Co-γ Ray of 15 Gy is more suitable for mutagenesis research on ripe pollen grains of upland cotton.
基金This work was supported by the NSFC innovation group project(Grant No.11921006)the National Grand Instrument Project(Grant No.2019YFF01014402)+1 种基金the United States Department of Energy(Grant No.DE-FG03-93ER40773)the NNSA(Grant No.DENA0003841)(CENTAUR).The PIC simulations were carried out using the High-Performance Computing Platform of Peking University。
文摘In this work,the high-energy-density plasmas(HEDP)evolved from joule-class-femtosecond-laser-irradiated nanowire-array(NWA)targets were numerically and experimentally studied.The results of particle-in-cell simulations indicate that ions accelerated in the sheath field around the surfaces of the nanowires are eventually confined in a plasma,contributing most to the high energy densities.The protons emitted from the front surfaces of the NWA targets provide rich information about the interactions that occur.We give the electron and ion energy densities for broad target parameter ranges.The ion energy densities from NWA targets were found to be an order of magnitude higher than those from planar targets,and the volume of the HEDP was several-fold greater.At optimal target parameters,8%of the laser energy can be converted to confined protons,and this results in ion energy densities at the GJ/cm^(3) level.In the experiments,the measured energy of the emitted protons reached 4 MeV,and the changes in energy with the NWA’s parameters were found to fit the simulation results well.Experimental measurements of neutrons from 2H(d,n)3He fusion with a yield of(24±18)×10^(6)/J from deuterated polyethylene NWA targets also confirmed these results.
文摘In order to discuss the mechanisms of permanent fixation of wood compression set , compressed wood of Chinese fir (Cunninghamia lanceolata) was irradiated by gamma rays from 60 Co. The irradiation doses were 0 (for match specim ens), 10 3, 5×10 3, 10 4, 5×10 4, 10 5, 5×10 5, 10 6, 5×10 6 Gy, res pectively. Then the weight loss, the equilibrium moisture content (EMC), the rec overy of wood compression set after adsorption (RSA) and the recovery after imme rsion in water (RSW), as well as the creep behaviour under a dry specimen condit ion and under an adsorption and subsequent desorption condition were measured an d discussed. This research proves that the doses of gamma irradiation have great effect on weight loss, EMC, RSA, RSW of irradiated compressed wood of Chinese f ir. The weight loss and the EMC increase, the RSA and the RSW fall drastically w hen the irradiation doses exceed 10 6 Gy. Both the instantaneous compliance and the creep compliance of the irradiated specimens under the two measurement cond itions show the general trend of increase with the increase of gamma irradiation doses. It can be deduced that decomposition or decrystallization reactions happ en in the wood cell wall at high gamma irradiation doses, especially at doses of around 5×10 6 Gy. In addition, this research proves that decomposition of mai n components of cell wall of compressed wood will lead to fixation of compressio n set of wood to a certain degree.
基金Funded by the Natural Science Foundation of Hubei Province(2017CFB680)the Open Fund of the State Key Laboratory of Refractories and Metallurgy Wuhan University of Science and Technology(G201703)+2 种基金the Fund of Key Laboratory of Measurement and Control System for Offshore Environment,Fuqing Branch of Fujian Normal University(SI-KF1604)the Guiding Projects in Fujian Province(2018H0013)the Key Natural Fund Projects of Universities in Fujian Province(JZ160490)
文摘Using L-glutathione(GSH)as a capping agent,Zn Se/GSH quantum dots(QDs)were prepared under microwave irradiation and irradiated under dark,ultraviolet light and incandescent light,respectively.The properties and interaction of different lights irradiated ZnSe/GSH QDs and bovine serum albumin(BSA)were studied systematically.The fluorescence(FL)spectra results reveal that the quenching mechanism are all the static quenching in nature.The quenching constant(Ksv)and binding constant(K)value of different irradiated Zn Se/GSH QDs and BSA all increased with the change of light types from dark to incandescent light and UV light.The number of binding site(n)is close to 1 at different temperatures.The lighting types influence the enthalpy and entropy changes.The Fourier transform infrared(FTIR)spectra indicate that the light induced GSH ligand will facilitate photocatalytic oxidation on the surface of ZnSe/GSH QDs.The circular dichroism(CD)results show that theα-helicity content of BSA decreases from 60.34%,59.31%,to 58.79%under UV lighting,incandescent lighting and dark conditions.The interaction results of different lights illuminated ZnSe/GSH QDs with BSA by CD spectra method matches well with that by FL and FTIR spectra.That is,the interaction of ZnSe/GSH QDs and BSA from strong to weak is UV light,incandescent light and dark in sequence.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11475255,U1532261 and 11505282
文摘The influence of total dose irradiation on hot-carrier reliability of 65 nm n-type metal-oxide-semiconductor field- effect transistors （nMOSFETs） is investigated. Experimental results show that hot-carrier degradations on ir- radiated narrow channel nMOSFETs are greater than those without irradiation. The reason is attributed to radiation-induced charge trapping in shallow trench isolation （STI）. The electric field in the pinch-off region of the nMOSFET is enhanced by radiation-induced charge trapping in STI, resulting in a more severe hot-carrier effect.
文摘The ionoluminescence （IL） spectra of a ZnO single crystal irradiated with 2.5？MeV H＋＋ ions reveal that its intensity decreases with increasing the ion fluence, which indicates that the concentration of luminescence centers decreases with irradiation. The Gaussian decomposition results of the ZnO IL spectrum with a fluence of 1.77×10^11ions/cm^2 show that the spectrum is a superposition of energy levels centered at 1.75eV, 2.10eV, 3.12eV and 3.20eV. The four peaks are associated with electronic transitions from CB to VZnZn, CB to Oii, Znii to VB and the decay of self-trapped excitons, respectively. The results of single-exponential fitting demonstrate that different luminescent centers have different radiation resistance, which may explain why the emission decreases more slowly in the NBE band than in the DBE band. The agglomeration of larger point clusters accounts for the decrease in the concentration of luminescence centers and the increase in the concentration of non-luminescence centers, which indicates that the defect clusters induced by ion implantation act as nonradiative recombination centers and suppress light emission. The results of the photoluminescence spectra of a virgin ZnO single crystal and a ZnO single crystal irradiated with a fluence of 3.4××10^14ions/cm^2 show that compared with the virgin ZnO, the emission intensity of irradiated ZnO decreases by nearly two orders of magnitude, which demonstrates that the irradiation effect reduces radiative recombination and enhances nonradiative recombination. The conclusions of photoluminescence are consistent with the IL results.
基金This work was supported by the National Natural Science Foundation of China(NSFC)under Grant No.51402173the Fundamental Research Funds for the Central Universities(Grant No.FRF-TP-15-099A1).
文摘Photoluminescence(PL)bands from potassium dihydrogen phosphate(KDP)crystals are studied by time-resolved PL spectroscopy.KDPcrystals irradiated at a laser fluence of 11.5 J/cm^(2) are found to have the highest probability of phosphorus–oxygen hole center defects and the lowest probability of phosphorus-oxygen electric center defects,in contrast to the probabilities of these defects forKDPcrystals irradiated at 9.0 J/cm^(2).The probabilities of these two defects occurring in retired components are found to be intermediate between those for crystals irradiated at the two different fluences.The two types of defects may result fromtwo differentmechanisms and may interconvert under certain conditions.Thus,there are differences between the defects in KDP crystals irradiated at a high laser fluence and those in retired components.
文摘Positron lifetime spectrum was measured and the change of the free volume was studied for commercial polyethylene (PE) and polytetrafluoroethylene (PTFE) during 7-irradiation processing up to 265 kGy. The free volume size increases but the crystallinity decreases as irradiation dose increases in PE. Both qualities (free volume size and crystallinity) in PTFE display an opposite behavior. The fractional free volume reduces monotonically with increasing irradiation dose in both PE and PTFE. The competition between the crosslinkmg and the splitting decomposition in polymers can be used to understand the free volume changes with irradiation dose.
基金Supported by the National Basic Research Program of China under Grant No 2013CBA01502the National Natural Science Foundation of China under Grant Nos 11575011 and 11535001+1 种基金the National Grand Instrument Project under Grant No2012YQ030142the UK EPSRC under Grant Nos EP/G054950/1,EP/G056803/1,EP/G055165/1 and EP/M022463/1
文摘An improved indirect scheme for laser positron generation is proposed. The positron yields in high-ZZ metal targets irradiated by laser produced electrons from near-critical density plasmas and underdense plasma are investigated numerically. It is found that the positron yield is mainly affected by the number of electrons of energies up to several hundreds of MeV. Using near-critical density targets for electron acceleration, the number of high energy electrons can be increased dramatically. Through start-to-end simulations, it is shown that up to 6.78×10106.78×1010 positrons can be generated with state-of-the-art Joule-class femtosecond laser systems.
文摘We investigated the effect of treatment temperature on the magnetic property of iron nitride foils irradiated with nitrogen plasma. The iron nitride foils irradiated with nitrogen plasma were composed of ε-Fe2/3N, γ'-Fe4N and γ nitrogen austenite in α-Fe of the matrix. The saturation magnetization of the iron nitride foils decreased with increasing the surface temperature. The coercive force of the iron nitride foils increased with increasing the surface temperature.
文摘Blue colored topaz is one of the most recognized gemstones worldwide.However,it is rarely found in the field and the products have been made mostly in laboratory using gamma,neutron and electron irradiation or combinations of these devices.Origin of the blue color in topaz remains not well understood, largely due to a lack of nondestructive way in idnetifying the blue topaz.Here we report a compari-
文摘We theoretically study the dependence of photoelectron angular distribution on laser polarization direction in nitrogen molecules. The approach is based on the time-dependent density functional theory at the level of local density approximation complemented by self-interaction correction. It is found that photoelectron emission in one photon regime could be considered as a probing tool for the main character of different types of molecular orbitals （σ or π）. The pattern of emitted photoelectrons strongly depends on the polarized angle of the laser, for σ orbital, the number of photoelectron decreases with increasing the polarized angle, while for π orbital, it has the inverse relation to the polarized angle, which reveals the multi-electron effect in molecules. On the other hand, concerning the total photoelectron emission, one should take into account a few occupied orbitals instead of only the outmost one.
基金Supported by the Research Foundation for Young Scientist in Shandong Province under Grant No BS2013CL043
文摘The magnetism of highly oriented pyrolytic graphite （HOPG） induced by ion implantation is investigated with electron spin resonance （ESR） spectroscopy and magnetization measurements. The results indicate that the ESR spectra of the HOPG sample correlate with ion species, incident energy and dose of implantation. The correlation of the ESR spectra and magnetism of the HOPG sample with ：2C＋ ion implantation and H＋ ion implantation are studied in detail. The ferromagnetism of the HOPG sample is likely related to the asymmetric L1 line, which may be attributed to the interaction between localized defects and itinerant electrons occupied in the ＇impurity＇ band induced by ion implantation.
