The gas phase process of diamond film deposition from CH4/H2 gas mixture by electron-assisted chemical vapor deposition is simulated by the Monte-Carlo method. The electron velocity distribution under different E/P (t...The gas phase process of diamond film deposition from CH4/H2 gas mixture by electron-assisted chemical vapor deposition is simulated by the Monte-Carlo method. The electron velocity distribution under different E/P (the ratio of the electric field to gas pressure) is obtained, and the velocity profile is asymmetric. The variation of the number density of CH3 and H with different CH4 concentrations and gas pressure is investigated, and the optimal experimental parameters are obtained: the gas pressure is in the range of 2.5 kPa - 15 kPa and the CH4 concentration is in the range of 0.5% - 1%. The energy carried by the fragment CH3 as the function of the experiment parameters is investigated to explain the diamond growth at low temperature. These results will be helpful to the selection of optimum experimental conditions for high quality diamond films deposition in EACVD and the modeling of plasma chemical vapor deposition.展开更多
Chemical vapor deposition has been widely used to prepare the films of silicon, diamond and other inorganic species. Preparation of molecular crystal from chemical reactions in the vapor phase is seldom reported. Hept...Chemical vapor deposition has been widely used to prepare the films of silicon, diamond and other inorganic species. Preparation of molecular crystal from chemical reactions in the vapor phase is seldom reported. Hepta-condensed form of 1-propyne-1. 3-diol molecular crystal produced via vapor phase chemical reaction is reported and展开更多
Nanophase TiO2 Al2O3 composite particles synthesized by gas phase oxidation of TiCl4 and AlCl3 in an aerosol reactor were characterized by EDS, XPS, TG DTA, TEM, XRD and BET surface area analysis. The results showed t...Nanophase TiO2 Al2O3 composite particles synthesized by gas phase oxidation of TiCl4 and AlCl3 in an aerosol reactor were characterized by EDS, XPS, TG DTA, TEM, XRD and BET surface area analysis. The results showed that the morphological structure of the composite particles were influenced by AlCl3 feed ratio and reaction temperature. When Xinlet=2.80 and T=1400℃ , the composite particles were mainly composed of rutile TiO2，α Al2O3, and Al2TiO5, the average particle size was 25.3 nm and GSD (Geometric tandaed Squace Deviation) was 1.51. Other processing parameters affecting the particle size was also analyzed.展开更多
Nitrided- iron nanometer powder is prepared by thermal chemical vapor- phase reaction method,using Fe Cl2 · n H2 O and NH3 as starting material.The physical properties of the powder is measured by means of XRD,XP...Nitrided- iron nanometer powder is prepared by thermal chemical vapor- phase reaction method,using Fe Cl2 · n H2 O and NH3 as starting material.The physical properties of the powder is measured by means of XRD,XPS,TEM,VSM etc,and physical phase shape, size and magneticpropertiesof the powderis also characterized.Experimentresults show ni- trided- iron ultrafine powder of uniform,high pure,chain- of- spherical and high magnetics can be prepared by improving synthesis reaction instrument.The physical property index of the powder prepared in this instrumentis preferable to Tanaka′s same study results.展开更多
The use of clay minerals in the synthesis of nanosized noble metal particles to give increased catalytic activity was investigated. Nanosized platinum and ruthenium catalysts intercalated in clay (montmorillonite/hect...The use of clay minerals in the synthesis of nanosized noble metal particles to give increased catalytic activity was investigated. Nanosized platinum and ruthenium catalysts intercalated in clay (montmorillonite/hectorite) were synthesised and their catalytic activity was evaluated for the selective hydrogenation of three different α,β-unsaturated aldehydes, namely, crotonaldehyde, cinnamaldehyde, and citral, in a gas phase microreactor. The metal nano-sol was prepared by the chemical reduction of its precursor by the micellar technique in the presence of cetyl trimethyl ammonium bromide (CTAB), and the micelle stabilized metal particles were intercalated in the clay mineral by ion exchange. TEM micrographs of the catalyst particles showed that the metal particles were in the nanometre range. The average diameters of the particles were 1-25 nm. The effects of temperature, metal loading, and hydrogen flow rate on the catalytic activity and selectivity for α,β- unsaturated alcohol were studied. The results were correlated with the structural properties of the catalysts. The products formed in each reaction over the different catalysts showed that the catalysts were very active for hydrogenation, and the selectivity for the desired product, namely, α,β-unsaturated alcohol, was good. The metal catalysts intercalated in montmorillonite showed better selectivity than that in hectorite because of its higher acidity. Increased selectivity for α,β-unsaturated alcohol was observed with increased flow rate of hydrogen.展开更多
基金The project supported by the Nature Science Foundation of Hebei Province, China (No 502121)
文摘The gas phase process of diamond film deposition from CH4/H2 gas mixture by electron-assisted chemical vapor deposition is simulated by the Monte-Carlo method. The electron velocity distribution under different E/P (the ratio of the electric field to gas pressure) is obtained, and the velocity profile is asymmetric. The variation of the number density of CH3 and H with different CH4 concentrations and gas pressure is investigated, and the optimal experimental parameters are obtained: the gas pressure is in the range of 2.5 kPa - 15 kPa and the CH4 concentration is in the range of 0.5% - 1%. The energy carried by the fragment CH3 as the function of the experiment parameters is investigated to explain the diamond growth at low temperature. These results will be helpful to the selection of optimum experimental conditions for high quality diamond films deposition in EACVD and the modeling of plasma chemical vapor deposition.
文摘Chemical vapor deposition has been widely used to prepare the films of silicon, diamond and other inorganic species. Preparation of molecular crystal from chemical reactions in the vapor phase is seldom reported. Hepta-condensed form of 1-propyne-1. 3-diol molecular crystal produced via vapor phase chemical reaction is reported and
文摘Nanophase TiO2 Al2O3 composite particles synthesized by gas phase oxidation of TiCl4 and AlCl3 in an aerosol reactor were characterized by EDS, XPS, TG DTA, TEM, XRD and BET surface area analysis. The results showed that the morphological structure of the composite particles were influenced by AlCl3 feed ratio and reaction temperature. When Xinlet=2.80 and T=1400℃ , the composite particles were mainly composed of rutile TiO2，α Al2O3, and Al2TiO5, the average particle size was 25.3 nm and GSD (Geometric tandaed Squace Deviation) was 1.51. Other processing parameters affecting the particle size was also analyzed.
文摘Nitrided- iron nanometer powder is prepared by thermal chemical vapor- phase reaction method,using Fe Cl2 · n H2 O and NH3 as starting material.The physical properties of the powder is measured by means of XRD,XPS,TEM,VSM etc,and physical phase shape, size and magneticpropertiesof the powderis also characterized.Experimentresults show ni- trided- iron ultrafine powder of uniform,high pure,chain- of- spherical and high magnetics can be prepared by improving synthesis reaction instrument.The physical property index of the powder prepared in this instrumentis preferable to Tanaka′s same study results.
基金Supported by FONDECYT, Chile-Post Doctorate-2010 Project (3100010)
文摘The use of clay minerals in the synthesis of nanosized noble metal particles to give increased catalytic activity was investigated. Nanosized platinum and ruthenium catalysts intercalated in clay (montmorillonite/hectorite) were synthesised and their catalytic activity was evaluated for the selective hydrogenation of three different α,β-unsaturated aldehydes, namely, crotonaldehyde, cinnamaldehyde, and citral, in a gas phase microreactor. The metal nano-sol was prepared by the chemical reduction of its precursor by the micellar technique in the presence of cetyl trimethyl ammonium bromide (CTAB), and the micelle stabilized metal particles were intercalated in the clay mineral by ion exchange. TEM micrographs of the catalyst particles showed that the metal particles were in the nanometre range. The average diameters of the particles were 1-25 nm. The effects of temperature, metal loading, and hydrogen flow rate on the catalytic activity and selectivity for α,β- unsaturated alcohol were studied. The results were correlated with the structural properties of the catalysts. The products formed in each reaction over the different catalysts showed that the catalysts were very active for hydrogenation, and the selectivity for the desired product, namely, α,β-unsaturated alcohol, was good. The metal catalysts intercalated in montmorillonite showed better selectivity than that in hectorite because of its higher acidity. Increased selectivity for α,β-unsaturated alcohol was observed with increased flow rate of hydrogen.
