A novel laser processing technique was developed for making channels in the nano regime in this paper.A Nd:YAG laser was used to dry fabricate micro channels(25μm～100μm di- ameter)in a 1 cm^3 fused silica substrate...A novel laser processing technique was developed for making channels in the nano regime in this paper.A Nd:YAG laser was used to dry fabricate micro channels(25μm～100μm di- ameter)in a 1 cm^3 fused silica substrate by thermal-induced processing.By controlling the locations of these initiating micro channels on a silica cube,1D-controllable self-connecting nano fractures can be formed as rectangular channels.These nano channels are smooth and with extremely high aspect ratio(～10~4 depth to width ratio).A possible mechanism is proposed to explain the formation of the nano channels.This laser-based nano channel fabrication technique is fast and inexpensive,and with potential applications in capillary electrophoresis and electro-osmosis driven nano-filtration.展开更多
Using MEMS technology and transmission electron microscopy we show experimentally multiwalled carbon nanotubes with a mean fracture strength of larger than 100 GPa, which exceeds the earlier observations by a factor o...Using MEMS technology and transmission electron microscopy we show experimentally multiwalled carbon nanotubes with a mean fracture strength of larger than 100 GPa, which exceeds the earlier observations by a factor of approximately 3. These results are in excellent agreement with quantum-mechanical estimations. This performance is made possible by omitting chemical treatments from the sample preparation process, thus avoiding the formation of defects. High-resolution imaging is used to directly determine the number of fractured shells and the ehirality of the outer shell. Electron irradiation at 200keV for 10, 100 and 1800s lead to improvements of the maximum sustainable loads by factors of 2.4, 7.9 and 11.6 compared with non-irradiated samples of similar diameter. This effect is attributed to crosslinking between the shells. This procedure is a cost effective way of customizing the properties of multiwall nanotubes for many applications of interest ranging from nanocomposites to nanodevices.展开更多
基金The project supported by the National Natural Science Foundation of China (50375031)the Hong Kong Research Grants Council (CUHK 4416/99E)
文摘A novel laser processing technique was developed for making channels in the nano regime in this paper.A Nd:YAG laser was used to dry fabricate micro channels(25μm～100μm di- ameter)in a 1 cm^3 fused silica substrate by thermal-induced processing.By controlling the locations of these initiating micro channels on a silica cube,1D-controllable self-connecting nano fractures can be formed as rectangular channels.These nano channels are smooth and with extremely high aspect ratio(～10~4 depth to width ratio).A possible mechanism is proposed to explain the formation of the nano channels.This laser-based nano channel fabrication technique is fast and inexpensive,and with potential applications in capillary electrophoresis and electro-osmosis driven nano-filtration.
基金Supported by the National Natural Science Foundation of China under Grant No 50801009, and the National Science Foundation of USA （CMMI 0555734 and CHE-0550497）.
文摘Using MEMS technology and transmission electron microscopy we show experimentally multiwalled carbon nanotubes with a mean fracture strength of larger than 100 GPa, which exceeds the earlier observations by a factor of approximately 3. These results are in excellent agreement with quantum-mechanical estimations. This performance is made possible by omitting chemical treatments from the sample preparation process, thus avoiding the formation of defects. High-resolution imaging is used to directly determine the number of fractured shells and the ehirality of the outer shell. Electron irradiation at 200keV for 10, 100 and 1800s lead to improvements of the maximum sustainable loads by factors of 2.4, 7.9 and 11.6 compared with non-irradiated samples of similar diameter. This effect is attributed to crosslinking between the shells. This procedure is a cost effective way of customizing the properties of multiwall nanotubes for many applications of interest ranging from nanocomposites to nanodevices.
