Single crystalline 3C-SiC epitaxial layers are grown on φ 50mm Si wafers by a new resistively heated CVD/LPCVD system,using SiH_4,C_2H_4 and H_2 as gas precursors.X-ray diffraction and Raman scattering measurements a...Single crystalline 3C-SiC epitaxial layers are grown on φ 50mm Si wafers by a new resistively heated CVD/LPCVD system,using SiH_4,C_2H_4 and H_2 as gas precursors.X-ray diffraction and Raman scattering measurements are used to investigate the crystallinity of the grown films.Electrical properties of the epitaxial 3C-SiC layers with thickness of 1～3μm are measured by Van der Pauw method.The improved Hall mobility reaches the highest value of 470cm 2/(V·s) at the carrier concentration of 7.7×10 17 cm -3 .展开更多
A prismatic 204056-type high power lithium-ion battery was developed.Modified LiMn2O4 and carbonaceous mesophase sphere(CMS)were adopted as the cathode and anode,respectively.The effects of proportion of conductive ca...A prismatic 204056-type high power lithium-ion battery was developed.Modified LiMn2O4 and carbonaceous mesophase sphere(CMS)were adopted as the cathode and anode,respectively.The effects of proportion of conductive carbon black in cathode and the rest time after discharge on the electrochemical properties of batteries were investigated.The electrochemical tests show that the proportion of conductive carbon black in cathodes affects the high rate capability and discharge voltage plateau distinctly.The battery with 3.0%of conductive carbon black in cathode shows excellent electrochemical performances when being charged/discharged within 2.5-4.2 V at room temperature.The discharge capacity at 20C rate is 94.4%of that at 1C rate,and the capacity retention ratio charged at 1C and discharged at 5C is 86.6%after 390 cycles at room temperature.The test result of impulse discharge at 50C for 5 s shows that the battery has outstanding high rate discharge performance when the battery is in the depth of charge of 90%,75%,60%,45%,30%and 15%.The battery also shows good charge performance.When the battery is charged at 0.5C,1C,2C and 4C,the ratios of capacity for constant current charge are 98.4%,96.4%,91.0%and 72.9%of the whole charge capacity,respectively.In addition,the rest time after discharge affects the cycle performance distinctly when the battery is discharged at high rate.展开更多
The hydrocarbon detection techniques used currently are generally based on the theory of single-phase medium, but hydrocarbon reservoir mostly is multi-phase medium, therefore, multisolutions and uncertainties are exi...The hydrocarbon detection techniques used currently are generally based on the theory of single-phase medium, but hydrocarbon reservoir mostly is multi-phase medium, therefore, multisolutions and uncertainties are existed in the result of hydrocarbon detection. This paper presents a fast way to detect hydrocarbon in accordance with BOIT theory and laboratory data. The technique called DHAF technique has been applied to several survey area and obtained good result where the coincidence rate for hydrocarbon detection is higher than other similar techniques. The method shows a good prospect of the application in hydrocarbon detecting at exploration stage and in reservoir monitoring at production stage.展开更多
A series of carbonaceous mesophase spherule/activated carbon composites were prepared as anode materials for super lithium ion capacitors using carbonaceous mesophase spherules as the core materials and pitch as the a...A series of carbonaceous mesophase spherule/activated carbon composites were prepared as anode materials for super lithium ion capacitors using carbonaceous mesophase spherules as the core materials and pitch as the active carbon shell precursor.The structures of the composites were examined by scanning electron microscopy and X-ray diffractometry.The electrochemical performance was investigated in electric double layer capacitor and half-cell.The results show that,the composite exhibits good performance in both capacitor and battery with a high reversible capacity of 306.6 mA·h/g(0.2C) in the half-cell,along with a capacitance of 25.8 F/g in the capacitor when an optimum ratio of carbonaceous mesophase spherules to active carbon is adopted.The composite also shows a favorable rate performance and good cycle ability.A working model of this anode in super lithium ion capacitors was established.展开更多
Two types of mesocarbon microbeads(MCMB), one of which was green sphere and the other carbonized at 1000 ℃, were used to modify coal tar pitches, and their influences on the development of carbonaceous mesophase in c...Two types of mesocarbon microbeads(MCMB), one of which was green sphere and the other carbonized at 1000 ℃, were used to modify coal tar pitches, and their influences on the development of carbonaceous mesophase in coal tar pitches were investigated. Optical microscopy was used to observe the changes caused by the additives. The green MCMB could promote the growth of mesophase spheres. When the holding time at the final temperature was prolonged to 100 min, the green MCMB-modified pitch would produce excellent bulk mesophase. Carbonized MCMB prohibited the coalescence of mesophase spheres and was beneficial to forming super large mesophase spheres. In the green MCMB-modified pitch, mesophase spheres grew up using the added MCMB spheres as nuclei, i.e. the green MCMB continued to grow during heat-treatment, which accelerated the formation, growth, and coalescence of mesophase spheres. For carbonized MCMB, their active sites were passivated and they could not continue to grow. These inert spheres could aggregate around the newly-formed mesophase spheres, prohibiting the growth and coalescence of the mesophase spheres.展开更多
Effect of doping cerium in the support on the catalytic activity and side product of the reaction in the oxidative carbonylation of phenol to diphenyl carbonate (DPC) over the catalyst Pd-Co/Cu-Co-Mn mixed oxides was ...Effect of doping cerium in the support on the catalytic activity and side product of the reaction in the oxidative carbonylation of phenol to diphenyl carbonate (DPC) over the catalyst Pd-Co/Cu-Co-Mn mixed oxides was studied. The specific surface areas, crystal phase, valency, and content of the element on the surface of the catalysts were determined, and the products were detected by gas chromatograph/mass spectrometry (GC-MS). It is found that the catalyst without Ce shows higher activity than that with Ce, and the yields of DPC for the two cata-lysts can reach 30% and 23%, respectively. However, doping cerium can prevent the formation of 2-hydroxyphenyl benzoate and p-bromophenyl phenyl carbonate.展开更多
文摘Single crystalline 3C-SiC epitaxial layers are grown on φ 50mm Si wafers by a new resistively heated CVD/LPCVD system,using SiH_4,C_2H_4 and H_2 as gas precursors.X-ray diffraction and Raman scattering measurements are used to investigate the crystallinity of the grown films.Electrical properties of the epitaxial 3C-SiC layers with thickness of 1～3μm are measured by Van der Pauw method.The improved Hall mobility reaches the highest value of 470cm 2/(V·s) at the carrier concentration of 7.7×10 17 cm -3 .
基金Project(2007CB613607)supported by the National Basic Research Program of China
文摘A prismatic 204056-type high power lithium-ion battery was developed.Modified LiMn2O4 and carbonaceous mesophase sphere(CMS)were adopted as the cathode and anode,respectively.The effects of proportion of conductive carbon black in cathode and the rest time after discharge on the electrochemical properties of batteries were investigated.The electrochemical tests show that the proportion of conductive carbon black in cathodes affects the high rate capability and discharge voltage plateau distinctly.The battery with 3.0%of conductive carbon black in cathode shows excellent electrochemical performances when being charged/discharged within 2.5-4.2 V at room temperature.The discharge capacity at 20C rate is 94.4%of that at 1C rate,and the capacity retention ratio charged at 1C and discharged at 5C is 86.6%after 390 cycles at room temperature.The test result of impulse discharge at 50C for 5 s shows that the battery has outstanding high rate discharge performance when the battery is in the depth of charge of 90%,75%,60%,45%,30%and 15%.The battery also shows good charge performance.When the battery is charged at 0.5C,1C,2C and 4C,the ratios of capacity for constant current charge are 98.4%,96.4%,91.0%and 72.9%of the whole charge capacity,respectively.In addition,the rest time after discharge affects the cycle performance distinctly when the battery is discharged at high rate.
基金The project is sponsored by the Innovation Foundation of Key Lab of Geophysical Exploration under CNPC.
文摘The hydrocarbon detection techniques used currently are generally based on the theory of single-phase medium, but hydrocarbon reservoir mostly is multi-phase medium, therefore, multisolutions and uncertainties are existed in the result of hydrocarbon detection. This paper presents a fast way to detect hydrocarbon in accordance with BOIT theory and laboratory data. The technique called DHAF technique has been applied to several survey area and obtained good result where the coincidence rate for hydrocarbon detection is higher than other similar techniques. The method shows a good prospect of the application in hydrocarbon detecting at exploration stage and in reservoir monitoring at production stage.
基金Project(2007BAE12B00) supported by the National Key Technology R&D Program of ChinaProject(50974136) supported by the National Natural Science Foundation of China
文摘A series of carbonaceous mesophase spherule/activated carbon composites were prepared as anode materials for super lithium ion capacitors using carbonaceous mesophase spherules as the core materials and pitch as the active carbon shell precursor.The structures of the composites were examined by scanning electron microscopy and X-ray diffractometry.The electrochemical performance was investigated in electric double layer capacitor and half-cell.The results show that,the composite exhibits good performance in both capacitor and battery with a high reversible capacity of 306.6 mA·h/g(0.2C) in the half-cell,along with a capacitance of 25.8 F/g in the capacitor when an optimum ratio of carbonaceous mesophase spherules to active carbon is adopted.The composite also shows a favorable rate performance and good cycle ability.A working model of this anode in super lithium ion capacitors was established.
基金National Natural Science Foundation of China (No 50172034)
文摘Two types of mesocarbon microbeads(MCMB), one of which was green sphere and the other carbonized at 1000 ℃, were used to modify coal tar pitches, and their influences on the development of carbonaceous mesophase in coal tar pitches were investigated. Optical microscopy was used to observe the changes caused by the additives. The green MCMB could promote the growth of mesophase spheres. When the holding time at the final temperature was prolonged to 100 min, the green MCMB-modified pitch would produce excellent bulk mesophase. Carbonized MCMB prohibited the coalescence of mesophase spheres and was beneficial to forming super large mesophase spheres. In the green MCMB-modified pitch, mesophase spheres grew up using the added MCMB spheres as nuclei, i.e. the green MCMB continued to grow during heat-treatment, which accelerated the formation, growth, and coalescence of mesophase spheres. For carbonized MCMB, their active sites were passivated and they could not continue to grow. These inert spheres could aggregate around the newly-formed mesophase spheres, prohibiting the growth and coalescence of the mesophase spheres.
文摘Effect of doping cerium in the support on the catalytic activity and side product of the reaction in the oxidative carbonylation of phenol to diphenyl carbonate (DPC) over the catalyst Pd-Co/Cu-Co-Mn mixed oxides was studied. The specific surface areas, crystal phase, valency, and content of the element on the surface of the catalysts were determined, and the products were detected by gas chromatograph/mass spectrometry (GC-MS). It is found that the catalyst without Ce shows higher activity than that with Ce, and the yields of DPC for the two cata-lysts can reach 30% and 23%, respectively. However, doping cerium can prevent the formation of 2-hydroxyphenyl benzoate and p-bromophenyl phenyl carbonate.
