A practical technique to prepare transmission electron microscopy （TEM） thin foil containing powder particle was described and the data for the codeposition of two type particles with copper in the electroplating we...A practical technique to prepare transmission electron microscopy （TEM） thin foil containing powder particle was described and the data for the codeposition of two type particles with copper in the electroplating were presented. By depositing the particles which were distributed in CuSO4 electrolyte on cathode together with Cu^2＋ in electrodeposition bath, composite coating with suitable thickness could be formed. The thin coating was separated from the substrate and cut into a disc with diameter of 3mm for electropolishing. When the Cu matrix was thinned during electropolishing, the particles contained in the coating plate were also thinned to meet the suitable thickness for TEM observation. Various experimental results revealed that during electrodepositing the current density, pH-value of electrolyte and stirring mode all have significant effects on the distribution of particles in composite coating and the surface quality of the composite coating. The proper parameters used during electrodepositing to prepare TEM thin foil containing powder particle were discussed.展开更多
Microstructural evolutions and grain-boundary-character distribution during high-energy-beam welding of ultra-thin Fe Co-V foils were studied. Detailed data about the boundaries, coincidence site lattice（CSL） relati...Microstructural evolutions and grain-boundary-character distribution during high-energy-beam welding of ultra-thin Fe Co-V foils were studied. Detailed data about the boundaries, coincidence site lattice（CSL） relationships, grain sizes, and microstructural features were acquired from electron-backscatter diffraction（EBSD） maps. Moreover, the evolution of the magnetic properties during high-energy-beam welding was studied using vibrating sample magnetometry（VSM）. The fraction of low-angle boundaries was observed to increase in the fusion zones of both electron- and laser-beam-welded foils. The results showed that the fractions of low-Σ CSL boundaries（particularly twin boundaries, Σ3） in the fusion zones of the welded foils are higher than those in the base metal. Because the strain rates produced during high-energy-beam welding are very high（because of the extremely high cooling rate）, grain deformation by a slip mechanism is limited; therefore, deformation by grain twinning is dominant. VSM analysis showed that the magnetic properties of the welded foils, i.e., their remanence, coercive force, and energy product, changed significantly. The formation of large grains with preferred orientation parallel to the easy axis of magnetization was the main reason for the diminished magnetic properties.展开更多
Barium titanate（BTO） thin films were deposited on polycrystalline Ni foils by using the polymer assisted deposition（PAD） technique.The growth conditions including ambient and annealing temperatures were carefully ...Barium titanate（BTO） thin films were deposited on polycrystalline Ni foils by using the polymer assisted deposition（PAD） technique.The growth conditions including ambient and annealing temperatures were carefully optimized based on thermal dynamic analysis to control the oxidation processing and interdiffusion.Crystal structures,surface morphologies,and dielectric performance were examined and compared for BTO thin films annealed under different temperatures.Correlations between the fabrication conditions,microstructures,and dielectric properties were discussed.BTO thin films fabricated under the optimized conditions show good crystalline structure and promising dielectric properties with εr～ 400 and tan δ 〈 0.025 at 100 kHz.The data demonstrate that BTO films grown on polycrystalline Ni substrates by PAD are promising in device applications.展开更多
This research aims to investigate the effect of pulsed Nd：YAG laser micro-welding on the microstructure,texture and magnetic properties of ultra-thin Fe-Co-7.15 wt%V magnetic alloy.Optical microscopy,scanning electro...This research aims to investigate the effect of pulsed Nd：YAG laser micro-welding on the microstructure,texture and magnetic properties of ultra-thin Fe-Co-7.15 wt%V magnetic alloy.Optical microscopy,scanning electron microscopy and electron backscattered diffraction techniques were used to study the microstructural evolutions.Also,vibrating sample magnetometry was used to characterize the magnetic properties.The results showed that the fractions of low Σ coincidence site lattice boundaries in the fusion zone are higher than those of the base metal.The welded samples experience a significant decrease in their magnetic properties.It was found that the formation of new fiber texture in the fusion zone and grain coarsening are the most important factors affecting the magnetic properties.展开更多
Proton acceleration induced by a high-intensity ultraviolet laser interaction with a thin foil target was studied on an ultra-short KrF laser amplifier called LLG50 in China Institute of Atomic Energy （CIAE）. The ul...Proton acceleration induced by a high-intensity ultraviolet laser interaction with a thin foil target was studied on an ultra-short KrF laser amplifier called LLG50 in China Institute of Atomic Energy （CIAE）. The ultraviolet laser produced pulses with a high-contrast of 109, duration of 500 fs and energy of 30 mJ. The p-polarized laser was focused on a 2.1 #m gold foil by an off-axis parabola mirror （OAP） at an incident angle of 45°. The laser intensity was 1.2× 1017 W/cm2. The divergence angle for proton energy of 265 keV or higher was 30°, which was recorded by a CR39 detector covered with 2 μm aluminum foil in the target normal direction. The maximum proton energy recorded by a CR39 detector covered with a 4 μm aluminum foil was 440 keV, and the proton energy spectrum was measured by a proton spectrometer. The ultraviolet laser acquires a relatively lower hot electron temperature, which can be ascribed to the proportional relationship of Iλ2, but a higher hot electron density because of the higher laser absorption and critical density. Higher electron density availed to strengthen the sheath electric field, and increased the proton acceleration.展开更多
Proton acceleration experiments were carried out by a 1.2× 1018 W/cm2 ultra-short laser interaction with solid foil targets. The peak proton energy observed from an optimum target thickness of 7 μm in our experi...Proton acceleration experiments were carried out by a 1.2× 1018 W/cm2 ultra-short laser interaction with solid foil targets. The peak proton energy observed from an optimum target thickness of 7 μm in our experiments was 2.1 MeV. Peak proton energy and proton yield were investigated for different foil target thicknesses. It was shown that proton energy and conversion efficiency increased as the target became thinner, on one condition that the preplasma generated by the laser prepulse did not have enough shock energy and time to influence or destroy the target rear-surface. The existence of optimum foil thickness is due to the effect of the prepulse and hot electron transportation behavior on the foil target.展开更多
The effect of the polarizations of two counter-propagating relativistic laser pulses interacting with subwavelength thin solid-density foil is investigated.Three-dimensional particle-in-cell simulations and analytical...The effect of the polarizations of two counter-propagating relativistic laser pulses interacting with subwavelength thin solid-density foil is investigated.Three-dimensional particle-in-cell simulations and analytical modelling show that the interaction and resulting transverse instability depend strongly on the polarization directions as well as the intensity distribution of the resultant light field in the foil.The left-and right-handed circularly polarized laser pair with the same phase at the common focal spot in the ultrathin foil leads to the strongest distortion of the foil.The fastest growing mode and maximum growth rate depend mainly on the laser intensity.For all polarization and phase-difference combinations,the instability is weakest when the two laser pulses are exactly out of phase at the common focusing point in the foil.展开更多
文摘A practical technique to prepare transmission electron microscopy （TEM） thin foil containing powder particle was described and the data for the codeposition of two type particles with copper in the electroplating were presented. By depositing the particles which were distributed in CuSO4 electrolyte on cathode together with Cu^2＋ in electrodeposition bath, composite coating with suitable thickness could be formed. The thin coating was separated from the substrate and cut into a disc with diameter of 3mm for electropolishing. When the Cu matrix was thinned during electropolishing, the particles contained in the coating plate were also thinned to meet the suitable thickness for TEM observation. Various experimental results revealed that during electrodepositing the current density, pH-value of electrolyte and stirring mode all have significant effects on the distribution of particles in composite coating and the surface quality of the composite coating. The proper parameters used during electrodepositing to prepare TEM thin foil containing powder particle were discussed.
文摘Microstructural evolutions and grain-boundary-character distribution during high-energy-beam welding of ultra-thin Fe Co-V foils were studied. Detailed data about the boundaries, coincidence site lattice（CSL） relationships, grain sizes, and microstructural features were acquired from electron-backscatter diffraction（EBSD） maps. Moreover, the evolution of the magnetic properties during high-energy-beam welding was studied using vibrating sample magnetometry（VSM）. The fraction of low-angle boundaries was observed to increase in the fusion zones of both electron- and laser-beam-welded foils. The results showed that the fractions of low-Σ CSL boundaries（particularly twin boundaries, Σ3） in the fusion zones of the welded foils are higher than those in the base metal. Because the strain rates produced during high-energy-beam welding are very high（because of the extremely high cooling rate）, grain deformation by a slip mechanism is limited; therefore, deformation by grain twinning is dominant. VSM analysis showed that the magnetic properties of the welded foils, i.e., their remanence, coercive force, and energy product, changed significantly. The formation of large grains with preferred orientation parallel to the easy axis of magnetization was the main reason for the diminished magnetic properties.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 11028409 and 60976061)the Fundamental Research Funds for the Central Universities of China (Grant No. ZYGX2009Z0001)
文摘Barium titanate（BTO） thin films were deposited on polycrystalline Ni foils by using the polymer assisted deposition（PAD） technique.The growth conditions including ambient and annealing temperatures were carefully optimized based on thermal dynamic analysis to control the oxidation processing and interdiffusion.Crystal structures,surface morphologies,and dielectric performance were examined and compared for BTO thin films annealed under different temperatures.Correlations between the fabrication conditions,microstructures,and dielectric properties were discussed.BTO thin films fabricated under the optimized conditions show good crystalline structure and promising dielectric properties with εr～ 400 and tan δ 〈 0.025 at 100 kHz.The data demonstrate that BTO films grown on polycrystalline Ni substrates by PAD are promising in device applications.
文摘This research aims to investigate the effect of pulsed Nd：YAG laser micro-welding on the microstructure,texture and magnetic properties of ultra-thin Fe-Co-7.15 wt%V magnetic alloy.Optical microscopy,scanning electron microscopy and electron backscattered diffraction techniques were used to study the microstructural evolutions.Also,vibrating sample magnetometry was used to characterize the magnetic properties.The results showed that the fractions of low Σ coincidence site lattice boundaries in the fusion zone are higher than those of the base metal.The welded samples experience a significant decrease in their magnetic properties.It was found that the formation of new fiber texture in the fusion zone and grain coarsening are the most important factors affecting the magnetic properties.
基金supported by the Key Project of Chinese National Programs for Fundamental Research(973 Program)(No.2011CB808104)National Natural Science Foundation of China(Nos.10834008,11105234)
文摘Proton acceleration induced by a high-intensity ultraviolet laser interaction with a thin foil target was studied on an ultra-short KrF laser amplifier called LLG50 in China Institute of Atomic Energy （CIAE）. The ultraviolet laser produced pulses with a high-contrast of 109, duration of 500 fs and energy of 30 mJ. The p-polarized laser was focused on a 2.1 #m gold foil by an off-axis parabola mirror （OAP） at an incident angle of 45°. The laser intensity was 1.2× 1017 W/cm2. The divergence angle for proton energy of 265 keV or higher was 30°, which was recorded by a CR39 detector covered with 2 μm aluminum foil in the target normal direction. The maximum proton energy recorded by a CR39 detector covered with a 4 μm aluminum foil was 440 keV, and the proton energy spectrum was measured by a proton spectrometer. The ultraviolet laser acquires a relatively lower hot electron temperature, which can be ascribed to the proportional relationship of Iλ2, but a higher hot electron density because of the higher laser absorption and critical density. Higher electron density availed to strengthen the sheath electric field, and increased the proton acceleration.
基金supported by the Key Project of Chinese National Programs for Fundamental Research(973 Program)(No.2011CB808104)National Natural Science Foundation of China(Nos.11335013,11375276,11105234)
文摘Proton acceleration experiments were carried out by a 1.2× 1018 W/cm2 ultra-short laser interaction with solid foil targets. The peak proton energy observed from an optimum target thickness of 7 μm in our experiments was 2.1 MeV. Peak proton energy and proton yield were investigated for different foil target thicknesses. It was shown that proton energy and conversion efficiency increased as the target became thinner, on one condition that the preplasma generated by the laser prepulse did not have enough shock energy and time to influence or destroy the target rear-surface. The existence of optimum foil thickness is due to the effect of the prepulse and hot electron transportation behavior on the foil target.
基金supported by the National Natural Science Foundation of China(Grant Nos.12175310,12275356,12305268,12105362,12375244,12135009 and U22411281)the Natural Science Foundation of Hunan Province(Grant Nos.2021JJ40653,2020JJ5031 and 2025JJ30002)+1 种基金the Scientific Research Foundation of the Hunan Provincial Education Department(Grant No.22B0655)the Hunan Provincial Innovation Foundation for Postgraduates(Grant No.CX20210006)。
文摘The effect of the polarizations of two counter-propagating relativistic laser pulses interacting with subwavelength thin solid-density foil is investigated.Three-dimensional particle-in-cell simulations and analytical modelling show that the interaction and resulting transverse instability depend strongly on the polarization directions as well as the intensity distribution of the resultant light field in the foil.The left-and right-handed circularly polarized laser pair with the same phase at the common focal spot in the ultrathin foil leads to the strongest distortion of the foil.The fastest growing mode and maximum growth rate depend mainly on the laser intensity.For all polarization and phase-difference combinations,the instability is weakest when the two laser pulses are exactly out of phase at the common focusing point in the foil.
