Polytetrafluoroethylene(PTFE)is a low-background polymer that is applied to several applications in rare-event detection and underground low-background experiments.PTFE-based electronic substrates are important for re...Polytetrafluoroethylene(PTFE)is a low-background polymer that is applied to several applications in rare-event detection and underground low-background experiments.PTFE-based electronic substrates are important for reducing the detection limit of high-purity germanium detectors and scintillator calorimeters,which are widely applied in dark matter and 0υββdetection experiments.The traditional adhesive bonding method between PTFE and copper is not conducive to working in liquid nitrogen and extremely low-temperature environments.To avoid adhesive bonding,PTFE must be processed for surface metallization owing to the mismatch between the PTFE and copper conductive layer.Low-background PTFE matrix composites(m-PTFE)were selected to improve the electrical and mechanical properties of PTFE by introducing SiO_(2)/TiO_(2) particles.The microstructures,surface elements,and electrical properties of PTFE and m-PTFE were characterized and analyzed following ion implantation.PTFE and m-PTFE surfaces were found to be broken,degraded,and cross-linked by ion implantation,resulting in C=C conjugated double bonds,increased surface energy,and increased surface roughness.Comparably,the surface roughness,bond strength,and conjugated double bonds of m-PTFE were significantly more intense than those of PTFE.Moreover,the interface bonding theory between PTFE and the metal copper foil was analyzed using the direct metallization principle.Therefore,the peel strength of the optimized electronic substrates was higher than that of the industrial standard at extremely low temperatures,while maintaining excellent electrical properties.展开更多
Biodegradable stents made of magnesium(Mg)and its alloys have been developed to minimize persistent inflammation or in-stent restenosis,which are the main problems for permanent stents.However,their rapid corrosion be...Biodegradable stents made of magnesium(Mg)and its alloys have been developed to minimize persistent inflammation or in-stent restenosis,which are the main problems for permanent stents.However,their rapid corrosion behavior under physiological conditions leads to poor vascular compatibility and premature structural failure,which remains an important unsolved clinical problem.Herein,we demonstrate a new strategy for solving this problem by combining poly(ether imide)(PEI)coating and subsequent tantalum(Ta)ion implantation.The PEI coating covers the whole surface of the Mg stent uniformly via a spray coating technique and provides Mg with superior corrosion resistance and stable sirolimus-carrying ability.Ta ion implantation is conducted by a sputtering-based plasma immersion ion implantation technique only onto the luminal surface of the PEI-coated Mg stent.Its extremely short processing time(<30 s)permits preservation of the PEI coating’s corrosion protection ability and sirolimus loading characteristics.In addition,a Ta-implanted skin layer that forms on the topmost surface of the PEI coating plays an effective role in not only preventing a rapid release of sirolimus from the surface but also improving the PEI coating’s surface hydrophilicity.Based on in vitro cellular response and blood compatibility tests,Ta ion implantation leads to the improvement of endothelial cell adhesion/proliferation and suppression of platelet adhesion/activation regardless of sirolimus loading.These results indicate that the combination of PEI coating and Ta ion implantation has significant innovative potential to provide excellent vascular compatibility and prevent in-stent restenosis and thrombosis.展开更多
Introducing heteroatoms and defects is a significant strategy to improve oxygen evolution reaction(OER)performance of electrocatalysts.However,the synergistic interaction of the heteroatom and defect still needs furth...Introducing heteroatoms and defects is a significant strategy to improve oxygen evolution reaction(OER)performance of electrocatalysts.However,the synergistic interaction of the heteroatom and defect still needs further investigations.Herein,we demonstrated an oxygen vacancy-rich vanadium-doped Co_(3)O_(4)(V-Ov-Co_(3)O_(4)),fabricated by V-ion implantation,could be used for high-efficient OER catalysis.X-ray photoelectron spectra(XPS)and density functional theory(DFT)calculations show that the charge density of Co atom increased,and the reaction barrier of reaction pathway from O∗to HOO∗decreased.V-Ov-Co_(3)O_(4) catalyst shows a low overpotential of 329 mV to maintain current density of 10 mA·cm^(−2),and a small Tafel slope of 74.5 mV·dec^(−1).This modification provides us with valuable perception for future design of heteroatom-doped and defect-based electrocatalysts.展开更多
The structural and the size evolution of embedded In nanoparticles in Al synthesized by ion implantation and subsequent annealing are experimentally investigated. The average radius r of In nanoparticles is determined...The structural and the size evolution of embedded In nanoparticles in Al synthesized by ion implantation and subsequent annealing are experimentally investigated. The average radius r of In nanoparticles is determined as a function of annealing time in a temperature range between 423 K and 453 K. The structural transition of In nanoparticles with the crystallographic orientation In(200)[002] Al(200)[002] is observed to change into In(111)[110] Al(002)[110] with a critical particle radius between 2.3 nm and 2.6 nm. In addition, the growth of In nanoparticles in the annealing process is evidently governed by the diffusion limited Ostwald ripening. By further analyzing the experimental data, values of diffusion coefficient and activation energy are obtained.展开更多
Plasma immersion ion implantation(PⅢ) overcomes the direct exposure limit of traditional beamline ion implantation, and is suitable for the treatment of complex work-piece with large size. PⅢ technology is often use...Plasma immersion ion implantation(PⅢ) overcomes the direct exposure limit of traditional beamline ion implantation, and is suitable for the treatment of complex work-piece with large size. PⅢ technology is often used for surface modification of metal, plastics and ceramics. Based on the requirement of surface modification of large size insulating material, a composite full-directional PⅢ device based on RF plasma source and metal plasma source is developed in this paper. This device can not only realize gas ion implantation, but also can realize metal ion implantation, and can also realize gas ion mixing with metal ions injection. This device has two metal plasma sources and each metal source contains three cathodes. Under the condition of keeping the vacuum unchanged, the cathode can be switched freely. The volume of the vacuum chamber is about 0.94 m^3, and maximum vacuum degree is about 5?×?10^(-4) Pa. The density of RF plasma in homogeneous region is about 10~9 cm^(-3), and plasma density in the ion implantation region is about 10^(10) cm^(-3). This device can be used for large-size sample material PⅢ treatment, the maximum size of the sample diameter up to 400 mm. The experimental results show that the plasma discharge in the device is stable and can run for a long time. It is suitable for surface treatment of insulating materials.展开更多
The n-type PbTe doped with 0.05 mol fraction Pbl2 was hot-pressed, and the sintered samples were implanted by Sn+ ions at 200 KeV with doses of 6×1016 and 1×1017 ions/cm2. The effect of Sn+ implantation on t...The n-type PbTe doped with 0.05 mol fraction Pbl2 was hot-pressed, and the sintered samples were implanted by Sn+ ions at 200 KeV with doses of 6×1016 and 1×1017 ions/cm2. The effect of Sn+ implantation on thermoelectric properties was then investigated. The results show that Sn+ ion implantation can modify thermoelectric properties of the n-type PbTe and greatly improve the dimensionless展开更多
The surface layer of beryllium, specimen, has been strengthened by ion implantation. Its microhardness was measured. The hardness of surface layer has been calculated from the microhardness. The experimental data of t...The surface layer of beryllium, specimen, has been strengthened by ion implantation. Its microhardness was measured. The hardness of surface layer has been calculated from the microhardness. The experimental data of the wear rate indirectly Confirmed the reasonableness of the result of calculation. It is shown that the hardness of the surface layer strengthened, by ion implantation is nine times higher than that of beryllium itself. The relation between hardness and implantation dose was analysed and the best dose was obtained.展开更多
in order to achieve increased layer thickness, and wearing resistance, enhanced ion implantation with nitrogen has been carried out at temperatures of 100, 200, 400, and 600℃ with a dose of 4x 1018 ions’ cm-2. Using...in order to achieve increased layer thickness, and wearing resistance, enhanced ion implantation with nitrogen has been carried out at temperatures of 100, 200, 400, and 600℃ with a dose of 4x 1018 ions’ cm-2. Using the Plasma Source ion Implantation (PSII) device, specimens of Ti6Al4V alloy were implanted at elevated temperatures, using the ion flux as the heating source. Auger Electron Spectroscopy (AES), Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), micro-hardness measurements and pin-on-disk wearing tester were utilized to evaluate the surface property improvements. The thickness of the implanted layer increased by about an order of magnitude when the temperature was elevated from 100 to 600℃. Higher surface hardness and wearing resistance was also obtained in implantation under higher temperature. XRD image showed the presence of titanium nitrides on the implanted surface.展开更多
The propertiesof As+ implantedsilicon with anenergy160kev, differentdosesand anneal ing temperatures (500 700℃) were studied by means of x ray double crystaldiffraction( DCD) and ellipometricspectra ( ES) . Therockin...The propertiesof As+ implantedsilicon with anenergy160kev, differentdosesand anneal ing temperatures (500 700℃) were studied by means of x ray double crystaldiffraction( DCD) and ellipometricspectra ( ES) . Therockingcurvesof DCDweresimulated by multi layer modelof Dynamicaltheory,toobtainstrain distributionsasafunctionof depths. The1×1016 cm 2 annealed at600℃wasfoundthataepitaxiallayer wasformed . The ESresult provedtheseconclusions.展开更多
The peculiarities of energy dissipation transferred by solitary waves on defects such as freesurface, grain boundary, region with high concentration of vacancies are studied. One of theways of description of the long ...The peculiarities of energy dissipation transferred by solitary waves on defects such as freesurface, grain boundary, region with high concentration of vacancies are studied. One of theways of description of the long range effect taking place at ion implantation in metallic materialsis suggested.展开更多
Mass spectrometry is an essential part of ion implantation. Therefore, in order to guarantee beam purity avoiding contamination of the implanted samples, a system was developed for the high current implanter at the La...Mass spectrometry is an essential part of ion implantation. Therefore, in order to guarantee beam purity avoiding contamination of the implanted samples, a system was developed for the high current implanter at the Laboratory of Accelerators and Radiation Technologies (LATR) at the Instituto Superior Técnico. The system presented and discussed in this paper was developed using a LabVIEW code and uses a PC to control and display the mass spectrum. It also permits to save all data acquired for posterior analysis. In order to show some capabilities of this system, some experimental results are presented.展开更多
Heavy doped n-typeβ-G_(2)O_(3)(HD-G_(2)O_(3))was obtained by employing Si ion implantation technology on unintentionally dopedβ-G_(2)O_(3)single crystal substrates.To repair the G_(2)O_(3)lattice damage and activate...Heavy doped n-typeβ-G_(2)O_(3)(HD-G_(2)O_(3))was obtained by employing Si ion implantation technology on unintentionally dopedβ-G_(2)O_(3)single crystal substrates.To repair the G_(2)O_(3)lattice damage and activate the Si after implantation,the implanted substrates were annealed at 950℃,1000℃,and 1100℃,respectively.High-resolution X-ray diffraction and high-resolution transmission electron microscopy show that the ion-implanted layer has high lattice quality after high-temperature annealing at 1000℃.The minimum specific contact resistance is 9.2×10^(-5)Ω·cm^(2),which is attributed to the titanium oxide that is formed at the Ti/G_(2)O_(3)interface via rapid thermal annealing at 480℃.Based on these results,the lateralˇ-G_(2)O_(3)diodes were prepared,and the diodes exhibit high forward current density and low specific on-resistance.展开更多
Lithium niobate(LiNbO_(3),LN)channel and ridge waveguides have been successfully fabricated by He ion implantation,which has energy of 500 keV and fluence of 1.5×10^(16)ions/cm^(2) and is combined with lithograph...Lithium niobate(LiNbO_(3),LN)channel and ridge waveguides have been successfully fabricated by He ion implantation,which has energy of 500 keV and fluence of 1.5×10^(16)ions/cm^(2) and is combined with lithography and the precise diamond dicing technique.The refractive index profile of the annealed LN planar waveguide was reconstructed.The propagation loss of the channel waveguide with a width of 10μm and that of the ridge waveguides with widths of 25μm and 15μm were investigated by the end-face coupling method.In our work,the factors that affect the waveguide properties of channel and ridge waveguides were revealed.展开更多
Pure iron has been considered as a promising candidate for biodegradable implant applications.However,a faster degradation rate of pure iron is needed to meet the clinical requirement.In this work,metal vapor vacuum a...Pure iron has been considered as a promising candidate for biodegradable implant applications.However,a faster degradation rate of pure iron is needed to meet the clinical requirement.In this work,metal vapor vacuum arc technology was adopted to implant zinc ions into the surface of pure iron.Results showed that the implantation depth of zinc ions was about 60 nm.The degradation rate of pure iron was found to be accelerated after zinc ion implantation.The cytotoxicity tests revealed that the implanted zinc ions brought a slight increase on cytotoxicity of the tested cells.In terms of hemocompatibility,the hemolysis of zinc ion implanted pure iron was lower than 2%.However,zinc ions might induce more adhered and activated platelets on the surface of pure iron.Overall,zinc ion implantation can be a feasible way to accelerate the degradation rate of pure iron for biodegradable applications.展开更多
Structural and morphological changes as well as corrosion behavior of N+implanted Al in 0.6 M NaCl solution as function of N+fluence are investigated.The x-ray diffraction results confirmed AlN formation.The atomic fo...Structural and morphological changes as well as corrosion behavior of N+implanted Al in 0.6 M NaCl solution as function of N+fluence are investigated.The x-ray diffraction results confirmed AlN formation.The atomic force microscope(AFM)images showed larger grains on the surface of Al with increasing N+fluence.This can be due to the increased number of impacts of N+with Al atoms and energy conversion to heat,which increases the diffusion rate of the incident ions in the target.Hence,the number of the grain boundaries is reduced,resulting in corrosion resistance enhancement.Electrochemical impedance spectroscopy(EIS)and polarization results showed the increase of corrosion resistance of Al with increasing N+fluence.EIS data was used to simulate equivalent electric circuits(EC)for the samples.Strong dependence of the surface morphology on the EC elements was observed.The scanning electron microscope(SEM)analysis of the samples after corrosion test also showed that the surfaces of the implanted Al samples remain more intact relative to the untreated Al sample,consistent with the EIS and polarization results.展开更多
Surface mechanical attrition treatment(SMAT)method is an effective way to generate nanograined(NG)surface on Ti-25 Nb-3 Mo-2 Sn-3 Zr(wt.%)(named as TLM),a kind ofβ-type titanium alloy,and the achieved nanocrystalline...Surface mechanical attrition treatment(SMAT)method is an effective way to generate nanograined(NG)surface on Ti-25 Nb-3 Mo-2 Sn-3 Zr(wt.%)(named as TLM),a kind ofβ-type titanium alloy,and the achieved nanocrystalline surface was proved to promote positive functions of osteoblastic cells.In this work,to further endow the NG TLM alloy with both good osteogenic and antibacterial properties,magnesium(Mg),silver(Ag)ion or both were introduced onto the NG TLM surface by ion implantation process,as a comparison,the Mg and Ag ions were also co-implanted onto coarsegrained(CG)TLM surface.The obtained results show that subsequent ion implantation does not remarkably induce the surface roughness and topography alteration of the SMAT-treated layers,and it also has little impact on the microstructure of the SMAT-derivedβ-Ti nanograins.In addition,the implanted Mg and Ag ions are observed to exist as MgO and metallic Ag na noparticles(NPs)embedding tightly in theβ-Ti matrix with grain size of about 15 and 7 nm,respectively.Initial cell adhesion and functions(including proliferation,osteo-differentiation and extracellular matrix mineralization)of rabbit bone marrow mesenchymal stem cells(rBMMSCs)and the bacterial colonization of Staphylococcus aureus(S.aureus)on the different surfaces were investigated.The in-vitro experimental results reveal that the Mg and Ag single-ion implanted NG surface either significantly promotes the rBMMSCs response or inhibits the growth ofS.aureus,whereas the Mg/Ag coimplanted NG surface could concurrently enhance the rBMMSCs functions as well as inhibit the bacterial growth compared to the NG surface,and this efficacy is more pronounced as compared to the Mg/Ag co-implantation in the CG surface.The SMAT-achieved nanograins in the TLM surface layer are identified to not only play a leading role in determining the fate of rBMMSCs but also facilitate fabricating dualfunctio nal surface with both good osteogenic and antibacterial activities through co-implantation of Mg and Ag ions.Our investigation provides a new strategy to develop high-performance Ti-based implants for clinical application.展开更多
In this study,surface modification of monocrystalline silicon with two doses of hydrogen ion implantation and the plunge cutting process were conducted to explore the influence of hydrogen ions on the cutting behavior...In this study,surface modification of monocrystalline silicon with two doses of hydrogen ion implantation and the plunge cutting process were conducted to explore the influence of hydrogen ions on the cutting behavior of silicon.The results show that ion implantation is capable of deteriorating or improving the machinability of silicon,depending on the implantation dose.More cleavages and a reduction of critical depth of cut(CDoC)were observed for the silicon with a low implantation dose in the cutting direction of<100>in comparison to bare silicon,while no cleavage and an increase of CDoC were achieved after implantation with a high dose in the same cutting direction.Besides,the ductile cutting and thrust forces of the silicon with the low dose are larger than the bare silicon,but the forces are significantly reduced for the silicon after the high dose of implantation.The variation of the cutting forces is due to the different required stresses to overcome ductile and fracture deformation of silicon.展开更多
Direct synthesis of high-quality graphene on dielectric substrates is of great importance for the application of graphene-based electronics and optoelectronics. However, high-quality and uniform graphene film growth o...Direct synthesis of high-quality graphene on dielectric substrates is of great importance for the application of graphene-based electronics and optoelectronics. However, high-quality and uniform graphene film growth on dielectric substrates has proven challenging due to limited catalytic ability of dielectric substrates. Here, by employing a Cu ion implantation assisted method, high-quality and uniform graphene can be directly formed on various dielectric substrates including SiO2/Si, quartz glass, and sapphire substrates. The growth rate of graphene on the dielectric substrates was significantly improved due to the catalysis of Cu. Moreover, during the graphene growth process, the Cu atoms gradually evaporated away without involving any metal contamination. Furthermore, an interesting growth behavior of graphene on sapphire substrate was observed, and the results show the graphene domains growth tends to grow along the sapphire flat terraces. The ion implantation assisted approach could open up a new pathway for the direct synthesis of graphene and promote the potential application of graphene in electronics.展开更多
Despite anionic doping has been widely implemented to increase the visible light activity of TiO_(2),it often gives rise to a dramatical anodic shift in current onset potential.Herein,we show an effective method to ac...Despite anionic doping has been widely implemented to increase the visible light activity of TiO_(2),it often gives rise to a dramatical anodic shift in current onset potential.Herein,we show an effective method to achieve the huge cathodic shift of TiO_(2) photoanode with significantly enhanced visible light photo-electrochemical activity by nitrogen/cobalt coimplantation.The nitrogen/cobalt co-doped TiO_(2)nanorod arrays(N/Co-TiO_(2))exhibit a cathodic shift of 350 mV in onset potential relative to only nitrogen-doped TiO_(2)(N-TiO_(2)).Moreover,the visible-light(λ>420 nm)photocurrent density of N/Co-TiO_(2) reaches 0.46 mA/cm^(2),far exceeding 0.07 mA/cm^(2) in N-TiO_(2)at 1.23 V versus reversible hydrogen electrode(RHE).Systematic characterization studies demonstrate that the enhanced photo-electrochemical performance can be attributed to the surface synergic sputtering of high-energy nitrogen/cobalt ions.展开更多
The measuring of the depth profile and electrical activity of implantation impurity in the top nanometer range of silicon encounters various difficulties and limitations, though it is known to be critical in fabricati...The measuring of the depth profile and electrical activity of implantation impurity in the top nanometer range of silicon encounters various difficulties and limitations, though it is known to be critical in fabrication of silicon complementary metal–oxide–semiconductor(CMOS) devices. In the present work, SRIM program and photocarrier radiometry(PCR)are employed to monitor the boron implantation in industrial-grade silicon in an ultra-low implantation energy range from 0.5 keV to 5 keV. The differential PCR technique, which is improved by greatly shortening the measurement time through the simplification of reference sample, is used to investigate the effects of implantation energy on the frequency behavior of the PCR signal for ultra-shallow junction. The transport parameters and thickness of shallow junction, extracted via multi-parameter fitting the dependence of differential PCR signal on modulation frequency to the corresponding theoretical model, well explain the energy dependence of PCR signal and further quantitatively characterize the recovery degree of structure damage induced by ion implantation and the electrical activation degree of impurities. The monitoring of nmlevel thickness and electronic properties exhibits high sensitivity and apparent monotonicity over the industrially relevant implantation energy range. The depth profiles of implantation boron in silicon with the typical electrical damage threshold(YED) of 5.3×10^(15)cm^(-3) are evaluated by the SRIM program, and the determined thickness values are consistent well with those extracted by the differential PCR. It is demonstrated that the SRIM and the PCR are both effective tools to characterize ultra-low energy ion implantation in silicon.展开更多
基金supported by the National Natural Science Foundation of China(Nos.12141502 and 12005017).
文摘Polytetrafluoroethylene(PTFE)is a low-background polymer that is applied to several applications in rare-event detection and underground low-background experiments.PTFE-based electronic substrates are important for reducing the detection limit of high-purity germanium detectors and scintillator calorimeters,which are widely applied in dark matter and 0υββdetection experiments.The traditional adhesive bonding method between PTFE and copper is not conducive to working in liquid nitrogen and extremely low-temperature environments.To avoid adhesive bonding,PTFE must be processed for surface metallization owing to the mismatch between the PTFE and copper conductive layer.Low-background PTFE matrix composites(m-PTFE)were selected to improve the electrical and mechanical properties of PTFE by introducing SiO_(2)/TiO_(2) particles.The microstructures,surface elements,and electrical properties of PTFE and m-PTFE were characterized and analyzed following ion implantation.PTFE and m-PTFE surfaces were found to be broken,degraded,and cross-linked by ion implantation,resulting in C=C conjugated double bonds,increased surface energy,and increased surface roughness.Comparably,the surface roughness,bond strength,and conjugated double bonds of m-PTFE were significantly more intense than those of PTFE.Moreover,the interface bonding theory between PTFE and the metal copper foil was analyzed using the direct metallization principle.Therefore,the peel strength of the optimized electronic substrates was higher than that of the industrial standard at extremely low temperatures,while maintaining excellent electrical properties.
基金supported by a grant of the Korea Health Technology R&D Project through the Korea Health Industry Development Institute(KHIDI)funded by the Ministry of Health&Welfare,Republic of Korea(Grant No:HI18C0493)
文摘Biodegradable stents made of magnesium(Mg)and its alloys have been developed to minimize persistent inflammation or in-stent restenosis,which are the main problems for permanent stents.However,their rapid corrosion behavior under physiological conditions leads to poor vascular compatibility and premature structural failure,which remains an important unsolved clinical problem.Herein,we demonstrate a new strategy for solving this problem by combining poly(ether imide)(PEI)coating and subsequent tantalum(Ta)ion implantation.The PEI coating covers the whole surface of the Mg stent uniformly via a spray coating technique and provides Mg with superior corrosion resistance and stable sirolimus-carrying ability.Ta ion implantation is conducted by a sputtering-based plasma immersion ion implantation technique only onto the luminal surface of the PEI-coated Mg stent.Its extremely short processing time(<30 s)permits preservation of the PEI coating’s corrosion protection ability and sirolimus loading characteristics.In addition,a Ta-implanted skin layer that forms on the topmost surface of the PEI coating plays an effective role in not only preventing a rapid release of sirolimus from the surface but also improving the PEI coating’s surface hydrophilicity.Based on in vitro cellular response and blood compatibility tests,Ta ion implantation leads to the improvement of endothelial cell adhesion/proliferation and suppression of platelet adhesion/activation regardless of sirolimus loading.These results indicate that the combination of PEI coating and Ta ion implantation has significant innovative potential to provide excellent vascular compatibility and prevent in-stent restenosis and thrombosis.
基金supported by the National Natural Science Foundation of China(Grant Nos.12025503,U1867215,and U1932134)Hubei Provincial Natural Science Foundation(Grant No.2019CFA036)+1 种基金the Fundamental Research Funds for the Central Universities,China(Grant No.2042020kf0211)China Postdoctoral Science Foundation(Grant No.2020M682429)。
文摘Introducing heteroatoms and defects is a significant strategy to improve oxygen evolution reaction(OER)performance of electrocatalysts.However,the synergistic interaction of the heteroatom and defect still needs further investigations.Herein,we demonstrated an oxygen vacancy-rich vanadium-doped Co_(3)O_(4)(V-Ov-Co_(3)O_(4)),fabricated by V-ion implantation,could be used for high-efficient OER catalysis.X-ray photoelectron spectra(XPS)and density functional theory(DFT)calculations show that the charge density of Co atom increased,and the reaction barrier of reaction pathway from O∗to HOO∗decreased.V-Ov-Co_(3)O_(4) catalyst shows a low overpotential of 329 mV to maintain current density of 10 mA·cm^(−2),and a small Tafel slope of 74.5 mV·dec^(−1).This modification provides us with valuable perception for future design of heteroatom-doped and defect-based electrocatalysts.
基金Project supported by the National Natural Science Foundation of China(Grant No.11505160)the Director Foundation of Institute of Materials,Chinese Academy of Engineering Physics(Grant No.SJZD201406)
文摘The structural and the size evolution of embedded In nanoparticles in Al synthesized by ion implantation and subsequent annealing are experimentally investigated. The average radius r of In nanoparticles is determined as a function of annealing time in a temperature range between 423 K and 453 K. The structural transition of In nanoparticles with the crystallographic orientation In(200)[002] Al(200)[002] is observed to change into In(111)[110] Al(002)[110] with a critical particle radius between 2.3 nm and 2.6 nm. In addition, the growth of In nanoparticles in the annealing process is evidently governed by the diffusion limited Ostwald ripening. By further analyzing the experimental data, values of diffusion coefficient and activation energy are obtained.
文摘Plasma immersion ion implantation(PⅢ) overcomes the direct exposure limit of traditional beamline ion implantation, and is suitable for the treatment of complex work-piece with large size. PⅢ technology is often used for surface modification of metal, plastics and ceramics. Based on the requirement of surface modification of large size insulating material, a composite full-directional PⅢ device based on RF plasma source and metal plasma source is developed in this paper. This device can not only realize gas ion implantation, but also can realize metal ion implantation, and can also realize gas ion mixing with metal ions injection. This device has two metal plasma sources and each metal source contains three cathodes. Under the condition of keeping the vacuum unchanged, the cathode can be switched freely. The volume of the vacuum chamber is about 0.94 m^3, and maximum vacuum degree is about 5?×?10^(-4) Pa. The density of RF plasma in homogeneous region is about 10~9 cm^(-3), and plasma density in the ion implantation region is about 10^(10) cm^(-3). This device can be used for large-size sample material PⅢ treatment, the maximum size of the sample diameter up to 400 mm. The experimental results show that the plasma discharge in the device is stable and can run for a long time. It is suitable for surface treatment of insulating materials.
文摘The n-type PbTe doped with 0.05 mol fraction Pbl2 was hot-pressed, and the sintered samples were implanted by Sn+ ions at 200 KeV with doses of 6×1016 and 1×1017 ions/cm2. The effect of Sn+ implantation on thermoelectric properties was then investigated. The results show that Sn+ ion implantation can modify thermoelectric properties of the n-type PbTe and greatly improve the dimensionless
基金This project was suportod by Reijing Zhongguancun Associated Center of Analysis and Measurement
文摘The surface layer of beryllium, specimen, has been strengthened by ion implantation. Its microhardness was measured. The hardness of surface layer has been calculated from the microhardness. The experimental data of the wear rate indirectly Confirmed the reasonableness of the result of calculation. It is shown that the hardness of the surface layer strengthened, by ion implantation is nine times higher than that of beryllium itself. The relation between hardness and implantation dose was analysed and the best dose was obtained.
基金This item was supported by the Defense Science Foundation with Grant No.98JS50.3.3 HZ5801.
文摘in order to achieve increased layer thickness, and wearing resistance, enhanced ion implantation with nitrogen has been carried out at temperatures of 100, 200, 400, and 600℃ with a dose of 4x 1018 ions’ cm-2. Using the Plasma Source ion Implantation (PSII) device, specimens of Ti6Al4V alloy were implanted at elevated temperatures, using the ion flux as the heating source. Auger Electron Spectroscopy (AES), Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), micro-hardness measurements and pin-on-disk wearing tester were utilized to evaluate the surface property improvements. The thickness of the implanted layer increased by about an order of magnitude when the temperature was elevated from 100 to 600℃. Higher surface hardness and wearing resistance was also obtained in implantation under higher temperature. XRD image showed the presence of titanium nitrides on the implanted surface.
文摘The propertiesof As+ implantedsilicon with anenergy160kev, differentdosesand anneal ing temperatures (500 700℃) were studied by means of x ray double crystaldiffraction( DCD) and ellipometricspectra ( ES) . Therockingcurvesof DCDweresimulated by multi layer modelof Dynamicaltheory,toobtainstrain distributionsasafunctionof depths. The1×1016 cm 2 annealed at600℃wasfoundthataepitaxiallayer wasformed . The ESresult provedtheseconclusions.
文摘The peculiarities of energy dissipation transferred by solitary waves on defects such as freesurface, grain boundary, region with high concentration of vacancies are studied. One of theways of description of the long range effect taking place at ion implantation in metallic materialsis suggested.
文摘Mass spectrometry is an essential part of ion implantation. Therefore, in order to guarantee beam purity avoiding contamination of the implanted samples, a system was developed for the high current implanter at the Laboratory of Accelerators and Radiation Technologies (LATR) at the Instituto Superior Técnico. The system presented and discussed in this paper was developed using a LabVIEW code and uses a PC to control and display the mass spectrum. It also permits to save all data acquired for posterior analysis. In order to show some capabilities of this system, some experimental results are presented.
基金supported in part by the National Key Research and Development Program of China(No.2018YFB2200500)the National Natural Science Foundation of China(No.62050073,62090054,and 61975196)the Key Research Program of Frontier Sciences,CAS(No.QYZDY-SSW-JSC022)。
文摘Heavy doped n-typeβ-G_(2)O_(3)(HD-G_(2)O_(3))was obtained by employing Si ion implantation technology on unintentionally dopedβ-G_(2)O_(3)single crystal substrates.To repair the G_(2)O_(3)lattice damage and activate the Si after implantation,the implanted substrates were annealed at 950℃,1000℃,and 1100℃,respectively.High-resolution X-ray diffraction and high-resolution transmission electron microscopy show that the ion-implanted layer has high lattice quality after high-temperature annealing at 1000℃.The minimum specific contact resistance is 9.2×10^(-5)Ω·cm^(2),which is attributed to the titanium oxide that is formed at the Ti/G_(2)O_(3)interface via rapid thermal annealing at 480℃.Based on these results,the lateralˇ-G_(2)O_(3)diodes were prepared,and the diodes exhibit high forward current density and low specific on-resistance.
基金supported by the National Natural Science Foundation of China(Nos.11805142,11205096,and 11874243)the Natural Science Foundation of Shandong Province(No.ZR2020QF086)。
文摘Lithium niobate(LiNbO_(3),LN)channel and ridge waveguides have been successfully fabricated by He ion implantation,which has energy of 500 keV and fluence of 1.5×10^(16)ions/cm^(2) and is combined with lithography and the precise diamond dicing technique.The refractive index profile of the annealed LN planar waveguide was reconstructed.The propagation loss of the channel waveguide with a width of 10μm and that of the ridge waveguides with widths of 25μm and 15μm were investigated by the end-face coupling method.In our work,the factors that affect the waveguide properties of channel and ridge waveguides were revealed.
基金This work was supported by the National Basic Research Program of China(973 Program)(Grant No.2012CB619102)National Science Fund for Distinguished Young Scholars(Grant No.51225101)+1 种基金National Natural Science Foundation of China(Grant No.51431002)the NSFC/RGC Joint Research Scheme under(Grant No.51361165101)in China's Mainland and N_CUHK449/13 in Hong Kong,and Beijing Municipal Science and Technology Project(Z141100002814008).
文摘Pure iron has been considered as a promising candidate for biodegradable implant applications.However,a faster degradation rate of pure iron is needed to meet the clinical requirement.In this work,metal vapor vacuum arc technology was adopted to implant zinc ions into the surface of pure iron.Results showed that the implantation depth of zinc ions was about 60 nm.The degradation rate of pure iron was found to be accelerated after zinc ion implantation.The cytotoxicity tests revealed that the implanted zinc ions brought a slight increase on cytotoxicity of the tested cells.In terms of hemocompatibility,the hemolysis of zinc ion implanted pure iron was lower than 2%.However,zinc ions might induce more adhered and activated platelets on the surface of pure iron.Overall,zinc ion implantation can be a feasible way to accelerate the degradation rate of pure iron for biodegradable applications.
文摘Structural and morphological changes as well as corrosion behavior of N+implanted Al in 0.6 M NaCl solution as function of N+fluence are investigated.The x-ray diffraction results confirmed AlN formation.The atomic force microscope(AFM)images showed larger grains on the surface of Al with increasing N+fluence.This can be due to the increased number of impacts of N+with Al atoms and energy conversion to heat,which increases the diffusion rate of the incident ions in the target.Hence,the number of the grain boundaries is reduced,resulting in corrosion resistance enhancement.Electrochemical impedance spectroscopy(EIS)and polarization results showed the increase of corrosion resistance of Al with increasing N+fluence.EIS data was used to simulate equivalent electric circuits(EC)for the samples.Strong dependence of the surface morphology on the EC elements was observed.The scanning electron microscope(SEM)analysis of the samples after corrosion test also showed that the surfaces of the implanted Al samples remain more intact relative to the untreated Al sample,consistent with the EIS and polarization results.
基金financially supported by the National Natural Science Foundation of China(Nos.81501598,51631007 and 31700860)the China Postdoctoral Science Foundation(No.2017M612052)+1 种基金the Postdoctoral Foundation of Anhui Province(No.2017B211)the General Research Fund of Research Grant Council of Hong Kong(Nos.N HKU725-16,17207719 and 17214516)。
文摘Surface mechanical attrition treatment(SMAT)method is an effective way to generate nanograined(NG)surface on Ti-25 Nb-3 Mo-2 Sn-3 Zr(wt.%)(named as TLM),a kind ofβ-type titanium alloy,and the achieved nanocrystalline surface was proved to promote positive functions of osteoblastic cells.In this work,to further endow the NG TLM alloy with both good osteogenic and antibacterial properties,magnesium(Mg),silver(Ag)ion or both were introduced onto the NG TLM surface by ion implantation process,as a comparison,the Mg and Ag ions were also co-implanted onto coarsegrained(CG)TLM surface.The obtained results show that subsequent ion implantation does not remarkably induce the surface roughness and topography alteration of the SMAT-treated layers,and it also has little impact on the microstructure of the SMAT-derivedβ-Ti nanograins.In addition,the implanted Mg and Ag ions are observed to exist as MgO and metallic Ag na noparticles(NPs)embedding tightly in theβ-Ti matrix with grain size of about 15 and 7 nm,respectively.Initial cell adhesion and functions(including proliferation,osteo-differentiation and extracellular matrix mineralization)of rabbit bone marrow mesenchymal stem cells(rBMMSCs)and the bacterial colonization of Staphylococcus aureus(S.aureus)on the different surfaces were investigated.The in-vitro experimental results reveal that the Mg and Ag single-ion implanted NG surface either significantly promotes the rBMMSCs response or inhibits the growth ofS.aureus,whereas the Mg/Ag coimplanted NG surface could concurrently enhance the rBMMSCs functions as well as inhibit the bacterial growth compared to the NG surface,and this efficacy is more pronounced as compared to the Mg/Ag co-implantation in the CG surface.The SMAT-achieved nanograins in the TLM surface layer are identified to not only play a leading role in determining the fate of rBMMSCs but also facilitate fabricating dualfunctio nal surface with both good osteogenic and antibacterial activities through co-implantation of Mg and Ag ions.Our investigation provides a new strategy to develop high-performance Ti-based implants for clinical application.
基金The work described in this paper was jointly supported by the Research Committee(Project No.G-YBLE)State Key Laboratory of Ultra-precision Machining Technology(Project No.RUWB)of the Hong Kong Polytechnic University.
文摘In this study,surface modification of monocrystalline silicon with two doses of hydrogen ion implantation and the plunge cutting process were conducted to explore the influence of hydrogen ions on the cutting behavior of silicon.The results show that ion implantation is capable of deteriorating or improving the machinability of silicon,depending on the implantation dose.More cleavages and a reduction of critical depth of cut(CDoC)were observed for the silicon with a low implantation dose in the cutting direction of<100>in comparison to bare silicon,while no cleavage and an increase of CDoC were achieved after implantation with a high dose in the same cutting direction.Besides,the ductile cutting and thrust forces of the silicon with the low dose are larger than the bare silicon,but the forces are significantly reduced for the silicon after the high dose of implantation.The variation of the cutting forces is due to the different required stresses to overcome ductile and fracture deformation of silicon.
基金This work was supported by National Natural Science and Foundation of China (NSFC) (No. 11875077)The authors acknowledge the support by the State Key Laboratory and Beijing Radiation Center.
文摘Direct synthesis of high-quality graphene on dielectric substrates is of great importance for the application of graphene-based electronics and optoelectronics. However, high-quality and uniform graphene film growth on dielectric substrates has proven challenging due to limited catalytic ability of dielectric substrates. Here, by employing a Cu ion implantation assisted method, high-quality and uniform graphene can be directly formed on various dielectric substrates including SiO2/Si, quartz glass, and sapphire substrates. The growth rate of graphene on the dielectric substrates was significantly improved due to the catalysis of Cu. Moreover, during the graphene growth process, the Cu atoms gradually evaporated away without involving any metal contamination. Furthermore, an interesting growth behavior of graphene on sapphire substrate was observed, and the results show the graphene domains growth tends to grow along the sapphire flat terraces. The ion implantation assisted approach could open up a new pathway for the direct synthesis of graphene and promote the potential application of graphene in electronics.
基金the National Natural Science Foundation of China(Grant No.11875211)the Major Science and Technology Program of Changsha,China(Grant No.kq1902046)the Fundamental Research Funds for the Central Universities,China.
文摘Despite anionic doping has been widely implemented to increase the visible light activity of TiO_(2),it often gives rise to a dramatical anodic shift in current onset potential.Herein,we show an effective method to achieve the huge cathodic shift of TiO_(2) photoanode with significantly enhanced visible light photo-electrochemical activity by nitrogen/cobalt coimplantation.The nitrogen/cobalt co-doped TiO_(2)nanorod arrays(N/Co-TiO_(2))exhibit a cathodic shift of 350 mV in onset potential relative to only nitrogen-doped TiO_(2)(N-TiO_(2)).Moreover,the visible-light(λ>420 nm)photocurrent density of N/Co-TiO_(2) reaches 0.46 mA/cm^(2),far exceeding 0.07 mA/cm^(2) in N-TiO_(2)at 1.23 V versus reversible hydrogen electrode(RHE).Systematic characterization studies demonstrate that the enhanced photo-electrochemical performance can be attributed to the surface synergic sputtering of high-energy nitrogen/cobalt ions.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 61771103, 61704023, and 61601092)。
文摘The measuring of the depth profile and electrical activity of implantation impurity in the top nanometer range of silicon encounters various difficulties and limitations, though it is known to be critical in fabrication of silicon complementary metal–oxide–semiconductor(CMOS) devices. In the present work, SRIM program and photocarrier radiometry(PCR)are employed to monitor the boron implantation in industrial-grade silicon in an ultra-low implantation energy range from 0.5 keV to 5 keV. The differential PCR technique, which is improved by greatly shortening the measurement time through the simplification of reference sample, is used to investigate the effects of implantation energy on the frequency behavior of the PCR signal for ultra-shallow junction. The transport parameters and thickness of shallow junction, extracted via multi-parameter fitting the dependence of differential PCR signal on modulation frequency to the corresponding theoretical model, well explain the energy dependence of PCR signal and further quantitatively characterize the recovery degree of structure damage induced by ion implantation and the electrical activation degree of impurities. The monitoring of nmlevel thickness and electronic properties exhibits high sensitivity and apparent monotonicity over the industrially relevant implantation energy range. The depth profiles of implantation boron in silicon with the typical electrical damage threshold(YED) of 5.3×10^(15)cm^(-3) are evaluated by the SRIM program, and the determined thickness values are consistent well with those extracted by the differential PCR. It is demonstrated that the SRIM and the PCR are both effective tools to characterize ultra-low energy ion implantation in silicon.
