Three-dimensionally (3D) long range ordered macroporous SiC ceramics were prepared through infiltrating polymethylsilane (PMS) into the 3D ordered sacrificial silica template, pyrolysis and the template removal. It wa...Three-dimensionally (3D) long range ordered macroporous SiC ceramics were prepared through infiltrating polymethylsilane (PMS) into the 3D ordered sacrificial silica template, pyrolysis and the template removal. It was found that the pore size (84―658 nm), BET surface area (299.44―584.64 m2/g) and micropore volume (0.25―0.64 cm3/g) of the achieved porous SiC can be tailored by utilizing different sizes silica sphere templates. There exist three kinds of pores in the porous ceramics: sphere inversed pores, windows and mesopores (2―5 nm). The sphere inversed pores were packed as hcp structure and three dimensionally penetrated through the windows, and the mesopores endowed the porous ceramics surprising high BET surface areas and micropore volumes.展开更多
Patterned SiC and SiCN microstructures were successfully fabricated on the silicon substrates by using polydimethylsiloxane (PDMS) elastometric stamp as template, polycarbosilane (PCS) and polysilazane (PSZ) as precer...Patterned SiC and SiCN microstructures were successfully fabricated on the silicon substrates by using polydimethylsiloxane (PDMS) elastometric stamp as template, polycarbosilane (PCS) and polysilazane (PSZ) as preceramic polymers. The preparing process was followed by precursor infiltration, the curing of the precursor, demolding of the template and pyrolysis of the cured preceramic polymer pattern. It shows that the dimen- sions of the ceramic patterns can be tailored by using the PDMS molds with different di- mensions. The produced ceramic microstructures can be potentially applied in high tem- perature and high pressure environments due to the advanced properties of the SiC and SiCN ceramics.展开更多
Six bisazo compounds were synthesized by coupling 2-(49-aminophenyl)-6-aminobenzoxazole as diazo component with N-phenyl-N9-(2-hydroxy-3-naphthoyl)urea derivatives,and characterized by ultraviolet and visible spectros...Six bisazo compounds were synthesized by coupling 2-(49-aminophenyl)-6-aminobenzoxazole as diazo component with N-phenyl-N9-(2-hydroxy-3-naphthoyl)urea derivatives,and characterized by ultraviolet and visible spectroscopy(UV-Vis),Fourier transform infrared spectroscopy(FT-IR)and elemental analysis(EA).Using these bisazo compounds as charge generation materials and CT-191(2-methyl-4-(N,N-dibenzyl)aminobenzoaldehyde-1,1-diphenylhydrazone)as charge transportation material,organic photoconductive devices were prepared.The result from photoconductivity measurement of the devices shows that the bisazo compound from N-(2-methylphenyl)-N9-(2-hydroxy-3-naphthoyl)urea has the best xerographic performance,V_(0)=600 V,V_(R)=30 V,R_(d)=15 V·s^(-1),E_(1/2)=3.5 lx·s.展开更多
基金This work was supported by the National Natural Science Foundation of China (Grant No. 59972042)the Korea National Research Laboratory Program (Grant No. M10400000061-04J0000-06110) the Doctor Innovation Fund of National University of Defense Technology in China (2001-2004).
文摘Three-dimensionally (3D) long range ordered macroporous SiC ceramics were prepared through infiltrating polymethylsilane (PMS) into the 3D ordered sacrificial silica template, pyrolysis and the template removal. It was found that the pore size (84―658 nm), BET surface area (299.44―584.64 m2/g) and micropore volume (0.25―0.64 cm3/g) of the achieved porous SiC can be tailored by utilizing different sizes silica sphere templates. There exist three kinds of pores in the porous ceramics: sphere inversed pores, windows and mesopores (2―5 nm). The sphere inversed pores were packed as hcp structure and three dimensionally penetrated through the windows, and the mesopores endowed the porous ceramics surprising high BET surface areas and micropore volumes.
基金This work was supported by the National Natural Science Foundation of China (Grant No. 59972042) Korea National Research Laboratory Program (Grant No. M10400000061-04J0000-06110)the Doctor Innovation Fund of the National University of Defense Technogy in China(2001-2004).
文摘Patterned SiC and SiCN microstructures were successfully fabricated on the silicon substrates by using polydimethylsiloxane (PDMS) elastometric stamp as template, polycarbosilane (PCS) and polysilazane (PSZ) as preceramic polymers. The preparing process was followed by precursor infiltration, the curing of the precursor, demolding of the template and pyrolysis of the cured preceramic polymer pattern. It shows that the dimen- sions of the ceramic patterns can be tailored by using the PDMS molds with different di- mensions. The produced ceramic microstructures can be potentially applied in high tem- perature and high pressure environments due to the advanced properties of the SiC and SiCN ceramics.
文摘Six bisazo compounds were synthesized by coupling 2-(49-aminophenyl)-6-aminobenzoxazole as diazo component with N-phenyl-N9-(2-hydroxy-3-naphthoyl)urea derivatives,and characterized by ultraviolet and visible spectroscopy(UV-Vis),Fourier transform infrared spectroscopy(FT-IR)and elemental analysis(EA).Using these bisazo compounds as charge generation materials and CT-191(2-methyl-4-(N,N-dibenzyl)aminobenzoaldehyde-1,1-diphenylhydrazone)as charge transportation material,organic photoconductive devices were prepared.The result from photoconductivity measurement of the devices shows that the bisazo compound from N-(2-methylphenyl)-N9-(2-hydroxy-3-naphthoyl)urea has the best xerographic performance,V_(0)=600 V,V_(R)=30 V,R_(d)=15 V·s^(-1),E_(1/2)=3.5 lx·s.
