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水热合成法制备高长径比的银纳米线 总被引:8,自引:0,他引:8
以季铵盐型阳离子Gemini表面活性剂[C16H33(CH3)2N+(CH2)3N+(CH3)2C16H33]×2Br-(16-3-16)为结构导向剂和稳定剂,以六次甲基四胺为还原剂,用水热合成法由硝酸银制备了直径约30 nm、长约50 mm的银纳米线. 用X射线衍射(XRD)、紫外-可见吸收光谱和透射电子显微镜(TEM)等手段对制备产物的表征结果表明,所得银纳米线具有面心立方结构,并且是沿着{111}晶面生长的. 银纳米线的长度与反应时间有关,而直径则变化不大. 反应温度对产物的形貌有较大影响,在100和120℃下得到的是纳米线,而在150℃下得到的多为不规则的纳米颗粒. 相似文献
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新型介孔分子筛MCM-41的超微结构观察和表征 总被引:3,自引:0,他引:3
自 1992年Mobil公司合成出M4 1S系列新型介孔分子筛以来[1] ,介孔材料已广泛应用于催化和石油加工领域。本文采用偶联表面活性剂GEM16 6 16为模板剂成功合成了六方相MCM 4 1分子筛 ,并通过扫描电镜和透射电镜对其微观结构进行观察和表征。1 材料与方法GEM16 6 16表面活性剂由实验室自制。将一定量的GEM16 6 16表面活性剂溶于水 ,置于 30℃的水浴中搅拌 ,滴加乙胺 ,然后慢慢滴加正硅酸乙酯(TEOS) ,继续搅拌 2h。将反应液转移到自压反应釜中 ,在 10 0℃下晶化 4 8h得到产物。将产物在 5 5 0℃的空气气氛中焙烧 6h ,升温速度为 … 相似文献
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The driven polymer translocation through a nanopore with unbiased initial configuration has been studied by using Langevin dynamics(LD) simulations.It is found that the scaling relationship between translocation time and the polymer chain length is strongly affected by the friction coefficient in LD and the driving force.However,there is no scaling relationship between the translocation time and the friction coefficient.The translocation time is almost inversely proportional to the driving force,which is in agreement with those obtained in biased translocation.The scaling relationship between gyration radius(R g) of subchain at the trans side with the subchain length(L) is R g ~L 0.33 that is in good agreement with the limiting value for molten globule state,while the curve of R g of subchain at the cis side has two distinct stages.During translocation,the subchain at the cis side is being stretched gradually,and the structure of the subchain transforms from sphere-like to rod-like.When the effect of stretching reaches the tail end,the subchain is at the most stretched state.Finally the subchain will rapidly restore to coil structure.According to the results of force analysis,the retarding force at the trans side is more crucial during the practical translocation. 相似文献
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