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91.
The nucleation of diamond films could be greatly enhanced on mirror-polished Si substrate by a pulsed Nd:YAG laser beam without any thermal- and plasma-assisted processes during a very short time. The nucleation density increased with decreasing laser power density from 1.38×1010 to 1.17×109 W/cm2 and deposition pressure from 1013 to 4 mbar. The pulsed laser beam made no contribution to enhance nucleation at substrate temperature as low as 650°C. X-ray diffraction measurements showed the (1 1 1) diffraction peak of diamond for the samples obtained using only pulsed laser during 40 min. The enhanced nucleation and growth of diamond crystallites were attributed to effective excitation of reactive gases and etching of non-diamond carbon phases by the pulsed laser beam. 相似文献
92.
Cigang Xu Emmanuel Flahaut Sam R. Bailey Gareth Brown Jeremy Sloan Karl S. Coleman V. Clifford Williams Malcolm L. H. Green * . Inorganic Chemistry Laboratory University of Oxford Oxford OX QR UK 《高等学校化学研究》2002,18(2):130-132
IntroductionSingle walledcarbonnanotubes(SWNTs)havebeensynthesisedbyusingvariousmethods[1— 3] andthechemicalvapourdeposition (CVD )methodhasbeenconsideredasa promisingmethodto produceSWNTsonanindustrialscale[3— 5] .However ,alltheSWNT productssynthesisedtodateco… 相似文献
93.
A linear time-of-flight mass spectrometer (TOF-MS) has been constructed to measure mass distribution of negatively-charged clusters formed in the hot filament diamond chemical vapor deposition (CVD) process and in the metal evaporation. A conversion dynode made of CsI was employed to enhance detection efficiency of the large clusters greater than 10 000 amu. An atomic peak from the tungsten evaporation was used for the mass calibration of the carbon clusters. The carbon clusters produced in the CVD diamond process was loosely bound so that they were easily fragmented during passage through accelerating electric fields. The mass distribution measured with the TOF-MS system showed much less abundance of large clusters than those measured previously with the energy analyzer and Wien filter. 相似文献
94.
一种节状纳米碳纤维的CVD生长 总被引:2,自引:0,他引:2
介绍了以发泡Ni为催化剂、用CVD法生长节状纳米碳纤维的工艺过程,讨论了工艺参数对生成样品的产率和形貌的影响,同时还探讨了该样品的生长机理。认为催化剂的不同晶面分别有利于烃类气体的吸附解离或碳的沉积,因此催化剂颗粒的原始形貌影响了不同开貌的碳纤维生长。 相似文献
95.
采用化学气相沉积方法成功地生长出硫化锌多晶红外光学材料.加工后的成品多晶硫化锌尺寸为直径150mm,厚度为6mm;既有曲面的整流罩,又有平面窗口,蒸镀多层防反膜.由于采用了自制的活性硫化氢为原料,以及较好的工艺生长条件,生长的硫化锌红外光学材料长波透射比达到理论值75;.镀多层防反膜以后,中、长红外波段透过率均有所提高,但镀膜技术还有待改进.文中对硫化锌的透过曲线进行了分析与比较,结果表明我们生长的硫化锌杂质较少,是红外透过率高的原因.文中还测试了硫化锌的其它主要性能. 相似文献
96.
Well-aligned open-ended multi-walled carbon nanotube (MWCNT) arrays were prepared via chemical vapor deposition (CVD) method in porous anodic aluminum oxide (AAO) templates without depositing any transition metals as catalyst. Effects of the CVD temperature and heat treatment were studied in detail.Well-aligned open-ended MWCNT arrays were obtained at the CVD temperature above 600 ℃; when CVD temperature is reduced to around 550 ℃, CNTs, CNFs and other structures existed at the same time; no CNTs or carbon nanofibres (CNFs) could be found as the CVD temperature is below 500 ℃, and only amorphous carbon in the porous AAO template was found. Experimental results showed that the AAO template is catalytic during the CVD process, and it has the following two effects: to catalyze thermal decomposition of acetylene and to catalyze conversion of carbon decomposed from acetylene into CNTs or CNFs. Heat treatment could improve the graphitization degree, but it might also introduce new defects. 相似文献
97.
Controlled growth and field emission of vertically aligned AlN nanostructures with different morphologies 下载免费PDF全文
The controllable growth of three different morphologies of AlN
nanostructures (nanorod, nanotip and nanocrater) arrays are
successfully realized by using chemical vapour deposition (CVD)
technology. All three nanostructures are of single crystal h-AlN
with a growth orientation of [001]. Their growth is attributed to
the vapour-liquid-solid (VLS) mechanism. To investigate the factors
affecting field emission (FE) properties of AlN nanostructures, we
compare their FE behaviours in several aspects. Experimental results
show that AlN nanocrater arrays possess the best FE properties, such
as a threshold field of 7.2~V/μm and an emission current
fluctuation lower than 4%. Moreover, the three AlN nanostructures
all have good field emission properties compared with a number of
other excellent cathode nanomaterials, which suggests that they are
future promising FE nanomaterials. 相似文献
98.
99.
100.
CVD法制备纳米碳管的催化剂多是以Al2O3、SiO2或MgO作载体,Fe、 Ni或Co等过渡族金属为活性组分[1-3]. 相似文献