The GECAM series of satellites utilizes LaBr_(3)(Ce),LaBr_(3)(Ce,Sr),and NaI(Tl)crystals as sensitive materials for gamma-ray detectors(GRDs).To investigate the nonlinearity in the detection of low-energy gamma rays a...The GECAM series of satellites utilizes LaBr_(3)(Ce),LaBr_(3)(Ce,Sr),and NaI(Tl)crystals as sensitive materials for gamma-ray detectors(GRDs).To investigate the nonlinearity in the detection of low-energy gamma rays and address the errors in the calibration of the E-C relationship,comprehensive tests and comparative studies of the three aforementioned crystals were conducted using Compton electrons,radioactive sources,and mono-energetic X-rays.The nonlinearity test results of the Compton electrons and X-rays demonstrated substantial differences,with all three crystals presenting a higher nonlinearity for X/-rays than for Compton electrons.Despite the LaBr_(3)(Ce)and LaBr_(3)(Ce,Sr)crystals having higher absolute light yields,they exhibited a noticeable nonlinear decrease in the light yield,especially at energies below 400 keV.The NaI(Tl)crystal demonstrated an"excess"light output in the 6-200 keV range,reaching a maximum"excess"of 9.2%at 30 keV in the X-ray testing and up to 15.5%at 14 keV during Compton electron testing,indicating a significant advantage in the detection of low-energy gamma rays.Furthermore,we explored the underlying causes of the observed nonlinearity in these crystals.This study not only elucidates the detector responses of GECAM,but also initiates a comprehensive investigation of the nonlinearity of domestically produced lanthanum bromide and sodium iodide crystals.展开更多
Thanks to its 10-membered-ring structure with a three-dimensional uniform pore system and acid distribution, ZSM-5 zeolite is a key catalytic material for benzene methylation with methanol. After epitaxial inter-growt...Thanks to its 10-membered-ring structure with a three-dimensional uniform pore system and acid distribution, ZSM-5 zeolite is a key catalytic material for benzene methylation with methanol. After epitaxial inter-growth of a dense layer of shell consisting of nano-particles on the conventional ZSM-5 crystal surface, the MFI/MFI core-shell zeolite not only has much more active surface area, but also can enrich the diffusion and reaction pore system at the same time, which can significantly improve its catalytic performance. In contrast to the performance of conventional ZSM-5 catalyst, an indepth investigation on the reaction parameters of benzene methylation over the core-shell structured zeolite is of great significance.展开更多
Hydrogen can serve as a carrier to store renewable energy in large scale.However,hydrogen storage still remains a challenge in the current stage.It is difficult to meet the technical requirements applying the conventi...Hydrogen can serve as a carrier to store renewable energy in large scale.However,hydrogen storage still remains a challenge in the current stage.It is difficult to meet the technical requirements applying the conventional storage of compressed gaseous hydrogen in high-pressure tanks or the solid-state storage of hydrogen in suitable materials.In the present work,a gaseous and solid-state(G-S)hybrid hydrogen storage system with a low working pressure below 5 MPa for a 10 kW hydrogen energy storage experiment platform is developed and validated.A Ti-Mn type hydrogen storage alloy with an effective hydrogen capacity of 1.7 wt%was prepared for the G-S hybrid hydrogen storage system.The G-S hybrid hydrogen storage tank has a high volumetric hydrogen storage density of 40.07 kg H_(2)m^(-3) and stores hydrogen under pressure below5 MPa.It can readily release enough hydrogen at a temperature as low as-15C when the FC system is not fully activated and hot water is not available.The energy storage efficiency of this G-S hybrid hydrogen storage system is calculated to be 86.4%-95.9%when it is combined with an FC system.This work provides a method on how to design a G-S hydrogen storage system based on practical demands and demonstrates that the G-S hybrid hydrogen storage is a promising method for stationary hydrogen storage application.展开更多
Abstract: The microstructure and properties of heavily deformed Cu-Ag-Ce in situ nano-filamentary composite were studied in this paper. As cast, copper matrixes were dendritic and Ag-rich phases, some of which present...Abstract: The microstructure and properties of heavily deformed Cu-Ag-Ce in situ nano-filamentary composite were studied in this paper. As cast, copper matrixes were dendritic and Ag-rich phases, some of which present spheroidizing tendency, were embedded in Cu dentritic arms. After heavily deforming, Ag-rich phases develop into fibers: the thick fibers with a size of more than 50 nm and the thin ones with a size of less than 30 nm. Strengthening of Cu-Ag-Ce in situ nano-filamentary composite could be divided into two stages and the combination of different strength and conductivity could be obtained through controlling reducing area, intermediate heat treatment and stabilizing treatment. The results revealed that heavily deformed Cu-Ag-Ce in situ nano-filamentary composite had high strength ( >1.5GPa) and high conductivity(>65%IACS).展开更多
We have performed first-principles density functional theory calculations to investigate the retention and migration of hydrogen in Be_（22） W, a stable low-W intermetallic compound. The solution energy of interstiti...We have performed first-principles density functional theory calculations to investigate the retention and migration of hydrogen in Be_（22） W, a stable low-W intermetallic compound. The solution energy of interstitial H in Be_（22） W is found to be 0.49 eV lower, while the diffusion barrier, on the other hand, is higher by 0.13 eV compared to those in pure hcp-Be. The higher solubility and lower diffusivity for H atoms make Be_（22） W a potential beneficial secondary phase in hcp-Be to impede the accumulation of H atoms, and hence better resist H blistering. We also find that in Be_（22） W, the attraction between an interstitial H and a beryllium vacancy ranges from 0.34 eV to 1.08 eV, which indicates a weaker trapping for hydrogen than in pure Be. Our calculated results suggest that small size Be_（22） W particles in hcp-Be might serve as the hydrogen trapping centers, hinder hydrogen bubble growth, and improve the resistance to irradiation void swelling, just as dispersed oxide particles in steel do.展开更多
Highly cube textured Ni tapes are produced by heavy cold rolling and recrystallization annealing. The textured nickel tapes have been proven to be suitable substrates for YBCO superconducting tape. Nevertheless, rolli...Highly cube textured Ni tapes are produced by heavy cold rolling and recrystallization annealing. The textured nickel tapes have been proven to be suitable substrates for YBCO superconducting tape. Nevertheless, rolling damage and grain boundary grooves on Ni influence the epitaxial growth of highly textured buffer and YBCO layers. The polishing of the Ni substrate surface may play a crucial role in making it beneficial to epitaxial film deposition. In our work, several polishing methods were adopted on Ni to reduce the depth of rolling damage and grain boundary grooves. On the polished Ni substrates, textured Y2O3 buffer layers were deposited using RF sputtering. XRD results show that in-plane texture of Y2O3 films will minish with the decreasing of the Ni substrate surface roughness. AFM results show that average grain size of the Y2O3 film is biggest and surface is coarse in film on flatter Ni surface.展开更多
The effects of preparation methods, supports and active parts on both the activation and stability of catalyst for the sodium borohydride hydrolysis were studied, and the results showed that the activation and stabili...The effects of preparation methods, supports and active parts on both the activation and stability of catalyst for the sodium borohydride hydrolysis were studied, and the results showed that the activation and stability of the catalysts prepared by impregnation method is better than that prepared by chemical plating. Compared to exchange resin and activated alumina, the diatomite with high BET surface area and porosity is more suitable for as the catalyst’s support. Co is much better than Ni when used as catalytic active part.展开更多
A novel method of pellet calcification roasting-H_(2)SO_(4) leaching was proposed to efficiently separate and extract vanadium(V)from vanadium-titanium(V-Ti)magnetite concentrates.The leaching rate of V is as high as ...A novel method of pellet calcification roasting-H_(2)SO_(4) leaching was proposed to efficiently separate and extract vanadium(V)from vanadium-titanium(V-Ti)magnetite concentrates.The leaching rate of V is as high as 88.98%,while the leaching rate of impurity iron is only 1.79%.Moreover,the leached pellets can be used as raw materials for blast furnace ironmaking after secondary roasting.X-ray photoelectron spectroscopy(XPS)and scanning electron microscopy with energy dispersive X-ray spectrometry(SEMEDS)analyses showed that V^(3+)was oxidized to V^(5+)after roasting at 1200℃,and V^(5+)was then leached by H_(2)SO_(4).X-ray diffraction(XRD)analyses and single factor experiment revealed a minimal amount of dissolved Fe_(2)O_(3) during H_(2)SO_(4) leaching.Therefore,a high separation degree of V and iron(Fe)from V-Ti magnetite concentrate was achieved through H_(2)SO_(4) leaching.Compared with the traditional roastingleaching process,this process can achieve a high selectivity of V and Fe,and has excellent prospects for industrial production.展开更多
Li–O2 batteries have attracted significant interest in the past decade owing to their superior high specific energy density in contrast to conventional lithium ion batteries.An 8.7-Ah Li–O2 pouch cell with768.5 Wh k...Li–O2 batteries have attracted significant interest in the past decade owing to their superior high specific energy density in contrast to conventional lithium ion batteries.An 8.7-Ah Li–O2 pouch cell with768.5 Wh kg^-1 was fabricated and characterized in this investigation and the factors that influenced the electrochemical performance of the Li–O2 pouch cell were studied.In contrast to coin/Swagelok-type Li–O2 cells,it was demonstrated that the high-loading air electrode,pulverization of the Li anode,and the large-scale inhomogeneity of the large pouch cell are the major reasons for the failure of Li–O2 batteries with Ah capacities.In addition,safety tests of large Li–O2 pouch cells were conducted for the first time,including nail penetration,crushing,and thermal stability.It was indicated that a self-limiting mechanism is a key safety feature of these batteries,even when shorted.In this study,Li–O2 batteries were investigated in a new size and capacity-scale,which may provide useful insight into the development of practical pouch-type Li–O2 batteries.展开更多
Silicon nanowires of high purity and regular morphology are of prime importance to ensure high specific capacities of lithium-ion batteries and reproducible electrode assembly process.Using nickel formate as a metal c...Silicon nanowires of high purity and regular morphology are of prime importance to ensure high specific capacities of lithium-ion batteries and reproducible electrode assembly process.Using nickel formate as a metal catalyst precursor,straight silicon nanowires(65–150 nm in diameter)were directly prepared by electrolysis from the Ni/SiO2 porous pellets with 0.8 wt%nickel content in molten CaCl2 at 900℃.Benefiting from their straight appearance and high purity,the silicon nanowires therefore offered an initial coulombic efficiency of 90.53% and specific capacity of 3377 m Ah/g.In addition,the silicon nanowire/carbon composite exhibited excellent cycle performance,retaining 90.38%of the initial capacity after 100 cycles.Whilst further study on the charge storage performance is still ongoing,these preliminary results demonstrate that nickel formate is an efficient and effective metal catalyst precursor for catalytic preparation of high purity straight silicon nanowires via the molten salt electrolysis,which is suitable for large-scale production.展开更多
To obtain intrinsic overcharge boundary and investigate overcharge mechanism,here we propose an innovative method,the step overcharge test,to reduce the thermal crossover and distinguish the overcharge thermal behavio...To obtain intrinsic overcharge boundary and investigate overcharge mechanism,here we propose an innovative method,the step overcharge test,to reduce the thermal crossover and distinguish the overcharge thermal behavior,including 5%state of charge(SOC)with small current overcharge and resting until the temperature equilibrium under adiabatic conditions.The intrinsic thermal response and the self-excitation behaviour are analysed through temperature and voltage changes during the step overcharge period.Experimental results show that the deintercalated state of the cathode is highly correlated to self-heating parasitic reactions.Before reaching the upper limit of Negative/Positive(N/P)ratio,the temperature changes little,the heat generation is significantly induced by the reversible heat(endothermic)and ohmic heat,which could balance each other.Following that the lithium metal is gradually deposited on the surface of the anode and reacts with electrolyte upon overcharge,inducing selfheating side reaction.However,this spontaneous thermal reaction could be“self-extinguished”.When the lithium in cathode is completely deintercalated,the boundary point of overcharge is about 4.7 V(~148%SOC,>40℃),and from this point,the self-heating behaviour could be continuously triggered until thermal runaway(TR)without additional overcharge.The whole static and spontaneous process lasts for 115 h and the side reaction heat is beyond 320,000 J.The continuous self-excitation behavior inside the battery is attributed to the interaction between the highly oxidized cathode and the solvent,which leads to the dissolution of metal ions.The dissolved metal ions destroy the SEI(solid electrolyte interphase)film on the surface of the deposited Li of anode,which induces the thermal reaction between lithium metal and the solvent.The interaction between cathode,the deposited Li of anode,and solvent promotes the temperature of the battery to rise slowly.When the temperature of the battery reaches more than 60℃,the reaction between lithium metal and solvent is accelerated.After the temperature rises rapidly to the melting point of the separator,it triggers the thermal runaway of the battery due to the short circuit of the battery.展开更多
In this paper, two types of comparison analyses, bulk analysis and defect analysis, were carried out for marine steel. The results of laser-induced breakdown spectroscopy （LIBS） were compared with those of spark opt...In this paper, two types of comparison analyses, bulk analysis and defect analysis, were carried out for marine steel. The results of laser-induced breakdown spectroscopy （LIBS） were compared with those of spark optical emission spectrometry （Spark-OES） and scanning electron microscopy/energy dispersion spectroscopy （SEM/EDS） in the bulk and defect analyses. The comparison of the bulk analyses shows that the chemical contents of C, Si, Mn, P, S and Cr obtained from LIBS agree well with those determined using Spark-OES. The LIBS is slightly less precise than Spark-OES. Defects were characterized in the two-dimensional distribution analysis mode for Al, Mg, Ca, Si and other elements. Both the LIBS and SEM/EDS results show the enrichment of Al, Mg, Ca and Si at the defect position and the two methods agree well with each other. SEM/EDS cannot provide information about the difference in the chemical constituents when the differences between the defect position and the normal position are not significant. However, LIBS can provide this information, meaning that the sensitivity of LIBS is higher than that of SEM/EDS. LIBS can be used to rapidly characterize marine steel defects and provide guidance for improving metallurgical processes.展开更多
Recently, self-sustained oscillatory genetic regulatory networks （GRNs） have attracted significant attention in the biological field. Given a GRN, it is important to anticipate whether the network could generate osc...Recently, self-sustained oscillatory genetic regulatory networks （GRNs） have attracted significant attention in the biological field. Given a GRN, it is important to anticipate whether the network could generate oscillation with proper parameters, and what the key ingredients for the oscillation are. In this paper the ranges of some function-related parameters which are favorable to sustained oscillations are considered. In particular, some oscillatory motifs appearing with high-frequency in most of the oscillatory GRNs are observed. Moreover, there are some anti-oscillatory motifs which have a strong oscillation repressing effect. Some conclusions analyzing these motif effects and constructing oscillatory GRNs are provided.展开更多
We performe first-principles density functional theory calculations to investigate the stability and mechanical properties of various HfHx （0 ≤ x ≤ 1） phases. For pure Hf phases, the calculated results show that t...We performe first-principles density functional theory calculations to investigate the stability and mechanical properties of various HfHx （0 ≤ x ≤ 1） phases. For pure Hf phases, the calculated results show that the HCP and FCC phases are mechanically stable, while the BCC phase is unstable at 0 K. Also, as for various HfHx phases, we find that H location and concentration could have a significant effect on their stability and mechanical properties. When 0 ≤ x ≤ 0.25, the HCP phases with H at （tetrahedral） T sites are energetically most stable among various phases. The FCC and BCC phases with H at T sites turn to be relatively more favorable than the HCP phase when H concentration is higher than 0.25. Furthermore, our calculated results indicate that the H solution in Hf can largely affect their mechanical properties such as the bulk moduli （B） and shear moduli （G）.展开更多
Five-fold twinned nanostructures are intrinsically strained or relaxed by extended defects to satisfy the space-filling requirement.Although both of metallic and semiconductor five-fold twinned nanostructures show inh...Five-fold twinned nanostructures are intrinsically strained or relaxed by extended defects to satisfy the space-filling requirement.Although both of metallic and semiconductor five-fold twinned nanostructures show inhomogeneity in their cross-sectional strain distribution,the evident strain concentration at twin boundaries in the semiconductor systems has been found in contrast to the metallic systems.Naturally,a problem is raised how the chemical bonding characteristics of various five-fold twinned nanosystems affects their strain-relieving defect structures.Here using three-dimensional(3D)electron diffraction mapping methodology,the intrinsic strain and the strain-relieving defects in a pentagonal Ag nanowire and a star-shaped boron carbide nanowire,both of them have basically equal radial twin-plane width about 30 nm,are nondestructively characterized.The non-uniform strain and defect distribution between the five single crystalline segments are found in both of the five-fold twinned nanowires.Diffraction intensity fine structure analysis for the boron carbide five-fold twinned nanowire indicates the presence of high-density of planar defects which are responsible for the accommodation of the intrinsic angular excess.However,for the Ag five-fold twinned nanowire,the star-disclination strain field is still present,although is partially relieved by the formation of localized stacking fault layers accompanied by partial dislocations.Energetic analysis suggests that the variety in the strain-relaxation ways for the two types of five-fold twinned nanowires could be ascribed to the large difference in shear modulus between the soft noble metal Ag and the superhard covalent compound boron carbide.展开更多
In the present work,the irradiation hardening behavior of a Chinese low-activation ferritic/martensitic steel CLF-1,a candidate for fusion reactor blankets,is studied.Specimens were irradiated with high-energy14N and5...In the present work,the irradiation hardening behavior of a Chinese low-activation ferritic/martensitic steel CLF-1,a candidate for fusion reactor blankets,is studied.Specimens were irradiated with high-energy14N and56Fe ions at the terminal of a cyclotron to three successively increasing damage levels of 0.05,0.1 and 0.2 displacements per atom(dpa)at about-50°C.The energy of the incident ions was dispersed to 11 successively decreasing grades using an energy degrader,thereby generating an atomic displacement damage plateau in the specimens from the surface to a depth of 25μm,which is sufficiently broad for the Vickers hardness test.Eight different loads(i.e.98 mN,196 m N,490 m N,980 m N,1.96 N,4.9 N,9.8 N and 19.6 N)were applied to the specimens to obtain the depth profiles of the Vickers hardness by using a microhardness tester.Hardening was observable at the lowest damage level,and increased with increasing irradiation dose.A power-law correlation of the Vickers hardness with the damage level(HV0=1.49+0.76 dpa0.31)is proposed.Testing with a nano-indentation technique was also performed,and a linear relationship between the Vickers micro-hardness and the nanohardness(HV0=0.83 H0)was observed.A comparison with other RAFM steels(CLAM,JLF-1,F82 H,EUROFER97 etc.)under neutron or charged particle irradiation conditions shows that most of the RAFM steels exhibit similar power-law exponents in the dose dependence of irradiation hardening.The difference in the irradiation hardening may be attributed to differences in microstructure prior to irradiation.展开更多
In the present work,the precipitate compositions and precipitate amounts of these elements（including the size distribution,volume fraction,and inter-precipitate distance） on the Cu-containing 7000 series aluminum al...In the present work,the precipitate compositions and precipitate amounts of these elements（including the size distribution,volume fraction,and inter-precipitate distance） on the Cu-containing 7000 series aluminum alloys（7150 and 7085 Al alloys）,are investigated by anomalous small-angle x-ray scattering（ASAXS） at various energies.The scattering intensity of 7150 alloy with T6 aging treatment decreases as the incident x-ray energy approaches the Zn absorption edge from the lower energy side,while scattering intensity does not show a noticeable energy dependence near the Cu absorption edge.Similar results are observed in the 7085 alloy in an aging process（120℃） by employing in-situ ASAXS measurements,indicating that the precipitate compositions should include Zn element and should not be strongly related to Cu element at the early stage after 10 min.In the aging process,the precipitate particles with an initial average size of ~ 8 ？A increase with aging time at an energy of 9.60 ke V,while the increase with a slower rate is observed at an energy of 9.65 ke V as near the Zn absorption edge.展开更多
The relationship between mechanical property and microstructure of NiTi shape memory alloy has been studied. It was founded that with increasing prestrain the memory recovery rate decreased, but the recovery stress an...The relationship between mechanical property and microstructure of NiTi shape memory alloy has been studied. It was founded that with increasing prestrain the memory recovery rate decreased, but the recovery stress and the recovery strain increased first and then decreased. The recovery stress and the recovery strain reached maximum at about 11% prestrain. The TEM(Transmission Electron Microscope) results of the alloy indicated that the microstructures with different prestrain of the alloy had obvious characters. At 9% prestrain, the martensite anamorphosis of the alloy still presented self-cooperation configuration, and some martensites have become thick obviously because of tropism. When the prestrain was 11%, the martensite anamorphosis has become completely thick and tropism became consistent. As the prestrain increased to 13%, the microstructures of the alloy have become disordered, the tropism became inconsistent and the interface became blurry.展开更多
Thin film microbattery is a promising micropower source for its high energy density and good cell performances, and the application of fast lithium ion conducting solids as electrolytes is thus very important. （Li 0....Thin film microbattery is a promising micropower source for its high energy density and good cell performances, and the application of fast lithium ion conducting solids as electrolytes is thus very important. （Li 0.5 La 0.5 ）TiO3 （LLTO） thin film electrolytes for thin film microbattery were prepared onto Pt/Si substrates using magnetron sputtering. As-deposited LLTO thin films showed amorphous-like phases and when deposition temperature increases the ionic conductivity raises accordingly. The ionic conductivity of LLTO thin film reaches 8.7×10 -6 S/cm when the deposition temperature is 400℃, which shows that the LLTO thin films deposited by magnetron sputtering are suitable for application as an electrolyte for thin film microbattery.展开更多
基金This work was supported by the National Key Research and Development Program(Nos.2022YFB3503600 and 2021YFA0718500)Strategic Priority Research Program of the Chinese Academy of Sciences(Nos.XDA15360102)National Natural Science Foundation of China(Nos.12273042 and 12075258).
文摘The GECAM series of satellites utilizes LaBr_(3)(Ce),LaBr_(3)(Ce,Sr),and NaI(Tl)crystals as sensitive materials for gamma-ray detectors(GRDs).To investigate the nonlinearity in the detection of low-energy gamma rays and address the errors in the calibration of the E-C relationship,comprehensive tests and comparative studies of the three aforementioned crystals were conducted using Compton electrons,radioactive sources,and mono-energetic X-rays.The nonlinearity test results of the Compton electrons and X-rays demonstrated substantial differences,with all three crystals presenting a higher nonlinearity for X/-rays than for Compton electrons.Despite the LaBr_(3)(Ce)and LaBr_(3)(Ce,Sr)crystals having higher absolute light yields,they exhibited a noticeable nonlinear decrease in the light yield,especially at energies below 400 keV.The NaI(Tl)crystal demonstrated an"excess"light output in the 6-200 keV range,reaching a maximum"excess"of 9.2%at 30 keV in the X-ray testing and up to 15.5%at 14 keV during Compton electron testing,indicating a significant advantage in the detection of low-energy gamma rays.Furthermore,we explored the underlying causes of the observed nonlinearity in these crystals.This study not only elucidates the detector responses of GECAM,but also initiates a comprehensive investigation of the nonlinearity of domestically produced lanthanum bromide and sodium iodide crystals.
文摘Thanks to its 10-membered-ring structure with a three-dimensional uniform pore system and acid distribution, ZSM-5 zeolite is a key catalytic material for benzene methylation with methanol. After epitaxial inter-growth of a dense layer of shell consisting of nano-particles on the conventional ZSM-5 crystal surface, the MFI/MFI core-shell zeolite not only has much more active surface area, but also can enrich the diffusion and reaction pore system at the same time, which can significantly improve its catalytic performance. In contrast to the performance of conventional ZSM-5 catalyst, an indepth investigation on the reaction parameters of benzene methylation over the core-shell structured zeolite is of great significance.
基金supported by State Grid Corporation of China(No.SGRIDGKJ[2016]123)Education Department of Guangxi Zhuang Autonomous Region(No.2019KY0021)the Natural Science Foundation of Guangxi Province(2019GXNSFBA185004,2018GXNSFAA281308,2019GXNSFAA245050)。
文摘Hydrogen can serve as a carrier to store renewable energy in large scale.However,hydrogen storage still remains a challenge in the current stage.It is difficult to meet the technical requirements applying the conventional storage of compressed gaseous hydrogen in high-pressure tanks or the solid-state storage of hydrogen in suitable materials.In the present work,a gaseous and solid-state(G-S)hybrid hydrogen storage system with a low working pressure below 5 MPa for a 10 kW hydrogen energy storage experiment platform is developed and validated.A Ti-Mn type hydrogen storage alloy with an effective hydrogen capacity of 1.7 wt%was prepared for the G-S hybrid hydrogen storage system.The G-S hybrid hydrogen storage tank has a high volumetric hydrogen storage density of 40.07 kg H_(2)m^(-3) and stores hydrogen under pressure below5 MPa.It can readily release enough hydrogen at a temperature as low as-15C when the FC system is not fully activated and hot water is not available.The energy storage efficiency of this G-S hybrid hydrogen storage system is calculated to be 86.4%-95.9%when it is combined with an FC system.This work provides a method on how to design a G-S hydrogen storage system based on practical demands and demonstrates that the G-S hybrid hydrogen storage is a promising method for stationary hydrogen storage application.
文摘Abstract: The microstructure and properties of heavily deformed Cu-Ag-Ce in situ nano-filamentary composite were studied in this paper. As cast, copper matrixes were dendritic and Ag-rich phases, some of which present spheroidizing tendency, were embedded in Cu dentritic arms. After heavily deforming, Ag-rich phases develop into fibers: the thick fibers with a size of more than 50 nm and the thin ones with a size of less than 30 nm. Strengthening of Cu-Ag-Ce in situ nano-filamentary composite could be divided into two stages and the combination of different strength and conductivity could be obtained through controlling reducing area, intermediate heat treatment and stabilizing treatment. The results revealed that heavily deformed Cu-Ag-Ce in situ nano-filamentary composite had high strength ( >1.5GPa) and high conductivity(>65%IACS).
基金Project supported by the National Magnetic Confinement Fusion Program of China(Grant Nos.2014GB104003 and 2015GB105001)the National Natural Science Foundation of China(Grant No.51504033)
文摘We have performed first-principles density functional theory calculations to investigate the retention and migration of hydrogen in Be_（22） W, a stable low-W intermetallic compound. The solution energy of interstitial H in Be_（22） W is found to be 0.49 eV lower, while the diffusion barrier, on the other hand, is higher by 0.13 eV compared to those in pure hcp-Be. The higher solubility and lower diffusivity for H atoms make Be_（22） W a potential beneficial secondary phase in hcp-Be to impede the accumulation of H atoms, and hence better resist H blistering. We also find that in Be_（22） W, the attraction between an interstitial H and a beryllium vacancy ranges from 0.34 eV to 1.08 eV, which indicates a weaker trapping for hydrogen than in pure Be. Our calculated results suggest that small size Be_（22） W particles in hcp-Be might serve as the hydrogen trapping centers, hinder hydrogen bubble growth, and improve the resistance to irradiation void swelling, just as dispersed oxide particles in steel do.
文摘Highly cube textured Ni tapes are produced by heavy cold rolling and recrystallization annealing. The textured nickel tapes have been proven to be suitable substrates for YBCO superconducting tape. Nevertheless, rolling damage and grain boundary grooves on Ni influence the epitaxial growth of highly textured buffer and YBCO layers. The polishing of the Ni substrate surface may play a crucial role in making it beneficial to epitaxial film deposition. In our work, several polishing methods were adopted on Ni to reduce the depth of rolling damage and grain boundary grooves. On the polished Ni substrates, textured Y2O3 buffer layers were deposited using RF sputtering. XRD results show that in-plane texture of Y2O3 films will minish with the decreasing of the Ni substrate surface roughness. AFM results show that average grain size of the Y2O3 film is biggest and surface is coarse in film on flatter Ni surface.
文摘The effects of preparation methods, supports and active parts on both the activation and stability of catalyst for the sodium borohydride hydrolysis were studied, and the results showed that the activation and stability of the catalysts prepared by impregnation method is better than that prepared by chemical plating. Compared to exchange resin and activated alumina, the diatomite with high BET surface area and porosity is more suitable for as the catalyst’s support. Co is much better than Ni when used as catalytic active part.
基金funded by the National Science Foundation of China(No.51704028)the Key R&D Program of Yunnan Province(No.2018IB027)。
文摘A novel method of pellet calcification roasting-H_(2)SO_(4) leaching was proposed to efficiently separate and extract vanadium(V)from vanadium-titanium(V-Ti)magnetite concentrates.The leaching rate of V is as high as 88.98%,while the leaching rate of impurity iron is only 1.79%.Moreover,the leached pellets can be used as raw materials for blast furnace ironmaking after secondary roasting.X-ray photoelectron spectroscopy(XPS)and scanning electron microscopy with energy dispersive X-ray spectrometry(SEMEDS)analyses showed that V^(3+)was oxidized to V^(5+)after roasting at 1200℃,and V^(5+)was then leached by H_(2)SO_(4).X-ray diffraction(XRD)analyses and single factor experiment revealed a minimal amount of dissolved Fe_(2)O_(3) during H_(2)SO_(4) leaching.Therefore,a high separation degree of V and iron(Fe)from V-Ti magnetite concentrate was achieved through H_(2)SO_(4) leaching.Compared with the traditional roastingleaching process,this process can achieve a high selectivity of V and Fe,and has excellent prospects for industrial production.
基金supported by the Beijing Municipal Science and Technology Project(Grant No.Z181100004518003)GRINM Youth Foundation Funded Project(Contract No.QGL20190060 or Grant No.69963)。
文摘Li–O2 batteries have attracted significant interest in the past decade owing to their superior high specific energy density in contrast to conventional lithium ion batteries.An 8.7-Ah Li–O2 pouch cell with768.5 Wh kg^-1 was fabricated and characterized in this investigation and the factors that influenced the electrochemical performance of the Li–O2 pouch cell were studied.In contrast to coin/Swagelok-type Li–O2 cells,it was demonstrated that the high-loading air electrode,pulverization of the Li anode,and the large-scale inhomogeneity of the large pouch cell are the major reasons for the failure of Li–O2 batteries with Ah capacities.In addition,safety tests of large Li–O2 pouch cells were conducted for the first time,including nail penetration,crushing,and thermal stability.It was indicated that a self-limiting mechanism is a key safety feature of these batteries,even when shorted.In this study,Li–O2 batteries were investigated in a new size and capacity-scale,which may provide useful insight into the development of practical pouch-type Li–O2 batteries.
基金financially supported by the National Key R&D Program of China (No. 2016YFB0100400)the National Natural Science Foundation of China (No. 51604032)
文摘Silicon nanowires of high purity and regular morphology are of prime importance to ensure high specific capacities of lithium-ion batteries and reproducible electrode assembly process.Using nickel formate as a metal catalyst precursor,straight silicon nanowires(65–150 nm in diameter)were directly prepared by electrolysis from the Ni/SiO2 porous pellets with 0.8 wt%nickel content in molten CaCl2 at 900℃.Benefiting from their straight appearance and high purity,the silicon nanowires therefore offered an initial coulombic efficiency of 90.53% and specific capacity of 3377 m Ah/g.In addition,the silicon nanowire/carbon composite exhibited excellent cycle performance,retaining 90.38%of the initial capacity after 100 cycles.Whilst further study on the charge storage performance is still ongoing,these preliminary results demonstrate that nickel formate is an efficient and effective metal catalyst precursor for catalytic preparation of high purity straight silicon nanowires via the molten salt electrolysis,which is suitable for large-scale production.
基金funded by the National Key Research and Development Program of China(2018YFB0104400)supported by the Beijing Natural Science Foundation(2214066)。
文摘To obtain intrinsic overcharge boundary and investigate overcharge mechanism,here we propose an innovative method,the step overcharge test,to reduce the thermal crossover and distinguish the overcharge thermal behavior,including 5%state of charge(SOC)with small current overcharge and resting until the temperature equilibrium under adiabatic conditions.The intrinsic thermal response and the self-excitation behaviour are analysed through temperature and voltage changes during the step overcharge period.Experimental results show that the deintercalated state of the cathode is highly correlated to self-heating parasitic reactions.Before reaching the upper limit of Negative/Positive(N/P)ratio,the temperature changes little,the heat generation is significantly induced by the reversible heat(endothermic)and ohmic heat,which could balance each other.Following that the lithium metal is gradually deposited on the surface of the anode and reacts with electrolyte upon overcharge,inducing selfheating side reaction.However,this spontaneous thermal reaction could be“self-extinguished”.When the lithium in cathode is completely deintercalated,the boundary point of overcharge is about 4.7 V(~148%SOC,>40℃),and from this point,the self-heating behaviour could be continuously triggered until thermal runaway(TR)without additional overcharge.The whole static and spontaneous process lasts for 115 h and the side reaction heat is beyond 320,000 J.The continuous self-excitation behavior inside the battery is attributed to the interaction between the highly oxidized cathode and the solvent,which leads to the dissolution of metal ions.The dissolved metal ions destroy the SEI(solid electrolyte interphase)film on the surface of the deposited Li of anode,which induces the thermal reaction between lithium metal and the solvent.The interaction between cathode,the deposited Li of anode,and solvent promotes the temperature of the battery to rise slowly.When the temperature of the battery reaches more than 60℃,the reaction between lithium metal and solvent is accelerated.After the temperature rises rapidly to the melting point of the separator,it triggers the thermal runaway of the battery due to the short circuit of the battery.
基金supported by a Special Fund for Nationally Important Instruments of China(No.2012YQ20018208)
文摘In this paper, two types of comparison analyses, bulk analysis and defect analysis, were carried out for marine steel. The results of laser-induced breakdown spectroscopy （LIBS） were compared with those of spark optical emission spectrometry （Spark-OES） and scanning electron microscopy/energy dispersion spectroscopy （SEM/EDS） in the bulk and defect analyses. The comparison of the bulk analyses shows that the chemical contents of C, Si, Mn, P, S and Cr obtained from LIBS agree well with those determined using Spark-OES. The LIBS is slightly less precise than Spark-OES. Defects were characterized in the two-dimensional distribution analysis mode for Al, Mg, Ca, Si and other elements. Both the LIBS and SEM/EDS results show the enrichment of Al, Mg, Ca and Si at the defect position and the two methods agree well with each other. SEM/EDS cannot provide information about the difference in the chemical constituents when the differences between the defect position and the normal position are not significant. However, LIBS can provide this information, meaning that the sensitivity of LIBS is higher than that of SEM/EDS. LIBS can be used to rapidly characterize marine steel defects and provide guidance for improving metallurgical processes.
基金Project supported by the National Natural Science Foundation of China (Grant No. 10975015)the National Basic Research Program of China (Grant No. 2007CB814800)
文摘Recently, self-sustained oscillatory genetic regulatory networks （GRNs） have attracted significant attention in the biological field. Given a GRN, it is important to anticipate whether the network could generate oscillation with proper parameters, and what the key ingredients for the oscillation are. In this paper the ranges of some function-related parameters which are favorable to sustained oscillations are considered. In particular, some oscillatory motifs appearing with high-frequency in most of the oscillatory GRNs are observed. Moreover, there are some anti-oscillatory motifs which have a strong oscillation repressing effect. Some conclusions analyzing these motif effects and constructing oscillatory GRNs are provided.
基金supported by the National Natural Science Foundation of China(Grant Nos.51401030 and 51504033)
文摘We performe first-principles density functional theory calculations to investigate the stability and mechanical properties of various HfHx （0 ≤ x ≤ 1） phases. For pure Hf phases, the calculated results show that the HCP and FCC phases are mechanically stable, while the BCC phase is unstable at 0 K. Also, as for various HfHx phases, we find that H location and concentration could have a significant effect on their stability and mechanical properties. When 0 ≤ x ≤ 0.25, the HCP phases with H at （tetrahedral） T sites are energetically most stable among various phases. The FCC and BCC phases with H at T sites turn to be relatively more favorable than the HCP phase when H concentration is higher than 0.25. Furthermore, our calculated results indicate that the H solution in Hf can largely affect their mechanical properties such as the bulk moduli （B） and shear moduli （G）.
基金National Natural Science Foundation of China(Grant Nos.51201015 and U1532262).
文摘Five-fold twinned nanostructures are intrinsically strained or relaxed by extended defects to satisfy the space-filling requirement.Although both of metallic and semiconductor five-fold twinned nanostructures show inhomogeneity in their cross-sectional strain distribution,the evident strain concentration at twin boundaries in the semiconductor systems has been found in contrast to the metallic systems.Naturally,a problem is raised how the chemical bonding characteristics of various five-fold twinned nanosystems affects their strain-relieving defect structures.Here using three-dimensional(3D)electron diffraction mapping methodology,the intrinsic strain and the strain-relieving defects in a pentagonal Ag nanowire and a star-shaped boron carbide nanowire,both of them have basically equal radial twin-plane width about 30 nm,are nondestructively characterized.The non-uniform strain and defect distribution between the five single crystalline segments are found in both of the five-fold twinned nanowires.Diffraction intensity fine structure analysis for the boron carbide five-fold twinned nanowire indicates the presence of high-density of planar defects which are responsible for the accommodation of the intrinsic angular excess.However,for the Ag five-fold twinned nanowire,the star-disclination strain field is still present,although is partially relieved by the formation of localized stacking fault layers accompanied by partial dislocations.Energetic analysis suggests that the variety in the strain-relaxation ways for the two types of five-fold twinned nanowires could be ascribed to the large difference in shear modulus between the soft noble metal Ag and the superhard covalent compound boron carbide.
基金sponsored by the National Magnetic Confinement Fusion Program(No.2011GB108003)National Natural Science Foundation of China(No.U1532262)。
文摘In the present work,the irradiation hardening behavior of a Chinese low-activation ferritic/martensitic steel CLF-1,a candidate for fusion reactor blankets,is studied.Specimens were irradiated with high-energy14N and56Fe ions at the terminal of a cyclotron to three successively increasing damage levels of 0.05,0.1 and 0.2 displacements per atom(dpa)at about-50°C.The energy of the incident ions was dispersed to 11 successively decreasing grades using an energy degrader,thereby generating an atomic displacement damage plateau in the specimens from the surface to a depth of 25μm,which is sufficiently broad for the Vickers hardness test.Eight different loads(i.e.98 mN,196 m N,490 m N,980 m N,1.96 N,4.9 N,9.8 N and 19.6 N)were applied to the specimens to obtain the depth profiles of the Vickers hardness by using a microhardness tester.Hardening was observable at the lowest damage level,and increased with increasing irradiation dose.A power-law correlation of the Vickers hardness with the damage level(HV0=1.49+0.76 dpa0.31)is proposed.Testing with a nano-indentation technique was also performed,and a linear relationship between the Vickers micro-hardness and the nanohardness(HV0=0.83 H0)was observed.A comparison with other RAFM steels(CLAM,JLF-1,F82 H,EUROFER97 etc.)under neutron or charged particle irradiation conditions shows that most of the RAFM steels exhibit similar power-law exponents in the dose dependence of irradiation hardening.The difference in the irradiation hardening may be attributed to differences in microstructure prior to irradiation.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11005143,11405259,and 51274046)the Scientific Research Foundation for the Returned Overseas Chinese Scholars,State Education Ministry of China(Grant No.[2014]1685)
文摘In the present work,the precipitate compositions and precipitate amounts of these elements（including the size distribution,volume fraction,and inter-precipitate distance） on the Cu-containing 7000 series aluminum alloys（7150 and 7085 Al alloys）,are investigated by anomalous small-angle x-ray scattering（ASAXS） at various energies.The scattering intensity of 7150 alloy with T6 aging treatment decreases as the incident x-ray energy approaches the Zn absorption edge from the lower energy side,while scattering intensity does not show a noticeable energy dependence near the Cu absorption edge.Similar results are observed in the 7085 alloy in an aging process（120℃） by employing in-situ ASAXS measurements,indicating that the precipitate compositions should include Zn element and should not be strongly related to Cu element at the early stage after 10 min.In the aging process,the precipitate particles with an initial average size of ~ 8 ？A increase with aging time at an energy of 9.60 ke V,while the increase with a slower rate is observed at an energy of 9.65 ke V as near the Zn absorption edge.
文摘The relationship between mechanical property and microstructure of NiTi shape memory alloy has been studied. It was founded that with increasing prestrain the memory recovery rate decreased, but the recovery stress and the recovery strain increased first and then decreased. The recovery stress and the recovery strain reached maximum at about 11% prestrain. The TEM(Transmission Electron Microscope) results of the alloy indicated that the microstructures with different prestrain of the alloy had obvious characters. At 9% prestrain, the martensite anamorphosis of the alloy still presented self-cooperation configuration, and some martensites have become thick obviously because of tropism. When the prestrain was 11%, the martensite anamorphosis has become completely thick and tropism became consistent. As the prestrain increased to 13%, the microstructures of the alloy have become disordered, the tropism became inconsistent and the interface became blurry.
文摘Thin film microbattery is a promising micropower source for its high energy density and good cell performances, and the application of fast lithium ion conducting solids as electrolytes is thus very important. （Li 0.5 La 0.5 ）TiO3 （LLTO） thin film electrolytes for thin film microbattery were prepared onto Pt/Si substrates using magnetron sputtering. As-deposited LLTO thin films showed amorphous-like phases and when deposition temperature increases the ionic conductivity raises accordingly. The ionic conductivity of LLTO thin film reaches 8.7×10 -6 S/cm when the deposition temperature is 400℃, which shows that the LLTO thin films deposited by magnetron sputtering are suitable for application as an electrolyte for thin film microbattery.
