Boron-doped diamond(BDD)films were deposited on the tungsten carbide substrates at different substrate temperatures ranging from 450 to 850°C by hot filament chemical vapor deposition(HFCVD)method.The effect of d...Boron-doped diamond(BDD)films were deposited on the tungsten carbide substrates at different substrate temperatures ranging from 450 to 850°C by hot filament chemical vapor deposition(HFCVD)method.The effect of deposition temperature on the properties of the boron-doped diamond films on tungsten carbide substrate was investigated.It is found that boron doping obviously enhances the growth rate of diamond films.A relatively high growth rate of 544 nm/h was obtained for the BDD film deposited on the tungsten carbide at 650°C.The added boron-containing precursor gas apparently reduced activation energy of film growth to be 53.1 kJ/mol,thus accelerated the rate of deposition chemical reaction.Moreover,Raman and XRD analysis showed that heavy boron doping(750 and 850°C)deteriorated the diamond crystallinity and produced a high defect density in the BDD films.Overall,600-700°C is found to be an optimum substrate temperature range for depositing BDD films on tungsten carbide substrate.展开更多
Based on the experimental results of Chen et al. to use the solar furnace and medium frequency induction furnace to extract boron impurity from metallurgical silicon, we propose a strong radiation catalysis mechanism ...Based on the experimental results of Chen et al. to use the solar furnace and medium frequency induction furnace to extract boron impurity from metallurgical silicon, we propose a strong radiation catalysis mechanism to explain the difference of reaction rates in these two furnaces. The postulate assuming the photons striking on the material not only increase the thermal energy of the molecules of reactants but also lower down the energy barrier of the reaction to speed up the chemical reaction. It is believed the photon catalysis mechanism is unlversall in most of high temperature chemical reactions and looking forward to more evidences for the postulate proposed in this article.展开更多
The segregation effect of B on the [100]（010） edge dislocation core in NiA1 single crystals is investigated using the DMol method and the discrete variational method within the framework of density functional theory...The segregation effect of B on the [100]（010） edge dislocation core in NiA1 single crystals is investigated using the DMol method and the discrete variational method within the framework of density functional theory. The impurity segregation en- ergy and the charge distribution are calculated. The effects of B on the dislocation motion are discussed. The results show that B prefers to segregate at the Center-Al dislocation core. Moreover, B forms strong bonding states with its neighboring host atoms, which may not be beneficial to the motion of the dislocation. Therefore, it can be expected that the strength of NiAl single crystals may be increased.展开更多
基金Project(51375011)supported by the National Natural Science Foundation of ChinaProject(15cxy49)supported by the Shanghai Municipal Education Commission,ChinaProject(16PJ025)supported by the Shanghai Pujiang Program,China
文摘Boron-doped diamond(BDD)films were deposited on the tungsten carbide substrates at different substrate temperatures ranging from 450 to 850°C by hot filament chemical vapor deposition(HFCVD)method.The effect of deposition temperature on the properties of the boron-doped diamond films on tungsten carbide substrate was investigated.It is found that boron doping obviously enhances the growth rate of diamond films.A relatively high growth rate of 544 nm/h was obtained for the BDD film deposited on the tungsten carbide at 650°C.The added boron-containing precursor gas apparently reduced activation energy of film growth to be 53.1 kJ/mol,thus accelerated the rate of deposition chemical reaction.Moreover,Raman and XRD analysis showed that heavy boron doping(750 and 850°C)deteriorated the diamond crystallinity and produced a high defect density in the BDD films.Overall,600-700°C is found to be an optimum substrate temperature range for depositing BDD films on tungsten carbide substrate.
文摘Based on the experimental results of Chen et al. to use the solar furnace and medium frequency induction furnace to extract boron impurity from metallurgical silicon, we propose a strong radiation catalysis mechanism to explain the difference of reaction rates in these two furnaces. The postulate assuming the photons striking on the material not only increase the thermal energy of the molecules of reactants but also lower down the energy barrier of the reaction to speed up the chemical reaction. It is believed the photon catalysis mechanism is unlversall in most of high temperature chemical reactions and looking forward to more evidences for the postulate proposed in this article.
基金supported by the National Natural Science Foundation of China (Grant No. 10705055)
文摘The segregation effect of B on the [100]（010） edge dislocation core in NiA1 single crystals is investigated using the DMol method and the discrete variational method within the framework of density functional theory. The impurity segregation en- ergy and the charge distribution are calculated. The effects of B on the dislocation motion are discussed. The results show that B prefers to segregate at the Center-Al dislocation core. Moreover, B forms strong bonding states with its neighboring host atoms, which may not be beneficial to the motion of the dislocation. Therefore, it can be expected that the strength of NiAl single crystals may be increased.
