A general expression for the relationship between induction periodand supersaturation was developed based on polynuclear approach.Different mechanism of primary nucleation in solution can beillustrated by the expressi...A general expression for the relationship between induction periodand supersaturation was developed based on polynuclear approach.Different mechanism of primary nucleation in solution can beillustrated by the expression. The results of induction perioddetermined by laser scattering method shows that the crystallizationof ciprofloxacin hydrochloride monohydrate in water/ethanol oraqueous solution is by the mechanism of primary nucleation followedby one-dimensional diffusion growth, and then on-dimensionalcontinuous or 'birth and spread' growth on crystal face. The growthmechanism on the crystal face is affected by temperature and solvent.展开更多
Investigated the effect of an addition of CaF2 on the crystallization of a glass-ceramic with abrasion resistance. X-ray diffraction, differential thermal analysis and scanning electron microscopy were used to determi...Investigated the effect of an addition of CaF2 on the crystallization of a glass-ceramic with abrasion resistance. X-ray diffraction, differential thermal analysis and scanning electron microscopy were used to determine the effect. The results showed that a suitable addition of CaF2 promoted crystallization by forming an interme- diate crystalline phase. CaF2 can decrease the temperature and active energy of the base-glass for crystallization. When 4 mass-% of CaF2-fraction is added in the glass, the crystallization temperature and active energy is 936 ℃and 172.75 kJ/mol respectively. When CaF2 is increased to 6 mass-%, the temperature and active energy decrease to 890 ℃ and 88.81 kJ/mol. CaF2 is an efficient nucleating agent for the glass-ceramics with abrasion resistant, the optimal content of CaF2 is about 6 mass-%.展开更多
An accurate four-line ac electrical resistance measurement (ERM)apparatus was developed. By using the ERM the crystallization kinetics of amorphous Ni80P20, FeZr2, Fe86B14 alloys were investigated. The experimental re...An accurate four-line ac electrical resistance measurement (ERM)apparatus was developed. By using the ERM the crystallization kinetics of amorphous Ni80P20, FeZr2, Fe86B14 alloys were investigated. The experimental results show that the ERM can identify the early stage of crystallization in amorphous alloys. The ERM detects a crystallization temperature range obviously wider than the DSC does, indicating that the ERM is more sensitive to the structure evolution in crystallization. For the eutectic or polymorphic crystallization, three distinct processes can be identified from the measured resistance variation: (i) crystal nucleation, (ii) subsequent growth of crystal nuclei, and (iii) coarsening of the crystallites. In the early stage of the primary crystallization, the ERM results reflect the nucleation information as well.展开更多
The melting kinetics of bulk SiC is studied by using classical molecular dynamics simulation.The mean square displacement,diffusion coefficient,Lindemann index and non-Gaussian parameter are used to analyze the melt n...The melting kinetics of bulk SiC is studied by using classical molecular dynamics simulation.The mean square displacement,diffusion coefficient,Lindemann index and non-Gaussian parameter are used to analyze the melt nucleation and macrokinetics in the melting process.Melting occurs when the superheated crystal spontaneously generates many Lindemann particles in which they coalesce together to form melt nucleation inside the crystal.The melting process is similar to the solidification process,but also experiences three processes such as nucleation,growth and relaxation.The melting process can be divided into premelting,accelerated melting and relaxation stages.Using the sectional method can properly reflect the kinetic characteristics of the melting process.展开更多
Previous reports about the growth of large graphene single crystals on polycrystalline metal substrates usually adopted the strategy of suppressing the nucleation by lowering the concentration of the feedstock, which ...Previous reports about the growth of large graphene single crystals on polycrystalline metal substrates usually adopted the strategy of suppressing the nucleation by lowering the concentration of the feedstock, which greatly limited the rate of the nucleation and the sequent growth. The emerging liquid metal catalyst possesses the characteristic of quasi-atomically smooth surface with high diffusion rate. In principle, it should be a naturally ideal platform for the lowdensity nucleation and the fast growth of graphene. However,the rapid growth of large graphene single crystals on liquid metals has not received the due attention. In this paper, we firstly purposed the insight into the rapid growth of large graphene single crystals on liquid metals. We obtained the millimeter-size graphene single crystals on liquid Cu. The rich free-electrons in liquid Cu accelerate the nucleation, and the isotropic smooth surface greatly suppresses the nucleation.Moreover, the fast mass-transfer of carbon atoms due to the excellent fluidity of liquid Cu promotes the fast growth with a rate up to 79 μm s^-1. We hope the research on the growth speed of graphene on liquid Cu can enrich the recognition of the growth behavior of two-dimensional(2 D) materials on the liquid metal. We also believe that the liquid metal strategy for the rapid growth of graphene can be extended to various 2 D materials and thus promote their future applications in the photonics and electronics.展开更多
文摘A general expression for the relationship between induction periodand supersaturation was developed based on polynuclear approach.Different mechanism of primary nucleation in solution can beillustrated by the expression. The results of induction perioddetermined by laser scattering method shows that the crystallizationof ciprofloxacin hydrochloride monohydrate in water/ethanol oraqueous solution is by the mechanism of primary nucleation followedby one-dimensional diffusion growth, and then on-dimensionalcontinuous or 'birth and spread' growth on crystal face. The growthmechanism on the crystal face is affected by temperature and solvent.
基金Supported by National Natural Science Foundation of China and Shanghai Baosteel Group Corporation(50174024)
文摘Investigated the effect of an addition of CaF2 on the crystallization of a glass-ceramic with abrasion resistance. X-ray diffraction, differential thermal analysis and scanning electron microscopy were used to determine the effect. The results showed that a suitable addition of CaF2 promoted crystallization by forming an interme- diate crystalline phase. CaF2 can decrease the temperature and active energy of the base-glass for crystallization. When 4 mass-% of CaF2-fraction is added in the glass, the crystallization temperature and active energy is 936 ℃and 172.75 kJ/mol respectively. When CaF2 is increased to 6 mass-%, the temperature and active energy decrease to 890 ℃ and 88.81 kJ/mol. CaF2 is an efficient nucleating agent for the glass-ceramics with abrasion resistant, the optimal content of CaF2 is about 6 mass-%.
基金This work was supported by the Chinese Academy of Sciences and the National Natural Science Foundation of China (Grant No. 59625101).
文摘An accurate four-line ac electrical resistance measurement (ERM)apparatus was developed. By using the ERM the crystallization kinetics of amorphous Ni80P20, FeZr2, Fe86B14 alloys were investigated. The experimental results show that the ERM can identify the early stage of crystallization in amorphous alloys. The ERM detects a crystallization temperature range obviously wider than the DSC does, indicating that the ERM is more sensitive to the structure evolution in crystallization. For the eutectic or polymorphic crystallization, three distinct processes can be identified from the measured resistance variation: (i) crystal nucleation, (ii) subsequent growth of crystal nuclei, and (iii) coarsening of the crystallites. In the early stage of the primary crystallization, the ERM results reflect the nucleation information as well.
基金supported by the National Natural Science Foundation of China (Grant No.61264004)the Special Funds for International Cooperation of the Ministry of Science and Technology of China (Grant No.2008DFA52210)+2 种基金the Key Technologies Research and Development Project of Guizhou Province (Grant No.[2011]3015)the Special Funds for Construction of Sci-Tech Innovative Talents Team of Guizhou Province (Grant No.[2011]4002)the Funds for International Sci-Tech Cooperation of Guizhou Province (Grant no.[2012]7004)
文摘The melting kinetics of bulk SiC is studied by using classical molecular dynamics simulation.The mean square displacement,diffusion coefficient,Lindemann index and non-Gaussian parameter are used to analyze the melt nucleation and macrokinetics in the melting process.Melting occurs when the superheated crystal spontaneously generates many Lindemann particles in which they coalesce together to form melt nucleation inside the crystal.The melting process is similar to the solidification process,but also experiences three processes such as nucleation,growth and relaxation.The melting process can be divided into premelting,accelerated melting and relaxation stages.Using the sectional method can properly reflect the kinetic characteristics of the melting process.
基金supported by the National Natural Science Foundation of China(21673161)the Sino-German Center for Research Promotion(1400)
文摘Previous reports about the growth of large graphene single crystals on polycrystalline metal substrates usually adopted the strategy of suppressing the nucleation by lowering the concentration of the feedstock, which greatly limited the rate of the nucleation and the sequent growth. The emerging liquid metal catalyst possesses the characteristic of quasi-atomically smooth surface with high diffusion rate. In principle, it should be a naturally ideal platform for the lowdensity nucleation and the fast growth of graphene. However,the rapid growth of large graphene single crystals on liquid metals has not received the due attention. In this paper, we firstly purposed the insight into the rapid growth of large graphene single crystals on liquid metals. We obtained the millimeter-size graphene single crystals on liquid Cu. The rich free-electrons in liquid Cu accelerate the nucleation, and the isotropic smooth surface greatly suppresses the nucleation.Moreover, the fast mass-transfer of carbon atoms due to the excellent fluidity of liquid Cu promotes the fast growth with a rate up to 79 μm s^-1. We hope the research on the growth speed of graphene on liquid Cu can enrich the recognition of the growth behavior of two-dimensional(2 D) materials on the liquid metal. We also believe that the liquid metal strategy for the rapid growth of graphene can be extended to various 2 D materials and thus promote their future applications in the photonics and electronics.
