In this paper, the Taguchi method with an L9（34） orthogonal array was used as experimental design to determine the optimum conditions for preparing ZnO nanoparticles via a mechanothermal route. ZnSO4·H20 and Na...In this paper, the Taguchi method with an L9（34） orthogonal array was used as experimental design to determine the optimum conditions for preparing ZnO nanoparticles via a mechanothermal route. ZnSO4·H20 and NaECO3 were used as starting materials. The effects of milling time, NaECO3/ZnSO·H20 molar ratio, and ball-to-powder mass ratio （BPR） on the bandgap （Eg） of ZnO nanoparticles were inves- tigated. The ranges of the investigated experimental conditions were 5-15 h for the milling time （t）, 1.0-1.2 for the Na2COa/ZnSO4·H20 mo- lar ratio （M）, and 10-30 for BPR. The milling time and BPR exhibited significant effects; an increase in milling time reduced the bandgap. The optimum conditions from this study were t3 = 15 h, M1 = l, and BPR2 = 20. Only two significant factors （t3, 15 h; BPR2, 20） were used to estimate the performance at the optimum conditions. The calculated bandgap was 3.12 eV, in reasonable agreement with the experimental results obtained under the optimized conditions.展开更多
Nanostructures of boron nitride (BN) including nanotubes, nanofibers and nanosheets having a large surface area are very useful in storing hydrogen and other gases. In the present paper we report the synthesis and cha...Nanostructures of boron nitride (BN) including nanotubes, nanofibers and nanosheets having a large surface area are very useful in storing hydrogen and other gases. In the present paper we report the synthesis and characterization of these nanostructures of BN using mechanothermal process. Under this process elemental boron powder is first ball milled to about 50 h in an inert atmosphere and then annealed at 1100℃ - 1250℃ for 6 h in the presence of NH3 gas. By this treatment nanotubes and other nanostructures of BN were synthesized. The diameter of BN nanotubes varied from 20 to 50 nm and most of them exhibited spindle or bamboo like morphology. Because of the large surface area, these nanotubes may be explored for a better hydrogen gas storage device as compared to the crystallized nanotubes. The main advantage of this technique is that the nanotubes can be grown in large quantity. A possible growth mechanism towards the evolution of such fascinating nano-objects of boron nitride has been discussed employing high-resolution transmission electron microscopy and photoluminescence.展开更多
The process of order to recover aluminum investigated. The CS was activating coal spoil （CS） in as a high value product was first characterized by X-ray fluorescence （XRF）, X-ray diffraction （XRD） and thermo- gr...The process of order to recover aluminum investigated. The CS was activating coal spoil （CS） in as a high value product was first characterized by X-ray fluorescence （XRF）, X-ray diffraction （XRD） and thermo- gravimetric analysis-differential scanning calorimetry （TGA-DSC） in order to determine the chemical and mineral compositions of the CS. Then a mechanothermal activation method was adopted to increase the aluminum activity in the coal spoil. Over 95% of the aluminum in the CS could be extracted using this activation method. The mechanothermal activation process promoted the destruc- tion of kaolinite structures and hindered the formation of amorphous γ-Al2O3. This resulted in a high aluminum leaching activity in the mechanothermally activated CS.展开更多
Hydroxyapatite-magnesium titanate composite nanopowders have been developed using a mechanothermal process.Thermal treatment of the milled powders at 700℃resulted in the formation of HAp/MgTiO_(3)-MgO nanocomposite.X...Hydroxyapatite-magnesium titanate composite nanopowders have been developed using a mechanothermal process.Thermal treatment of the milled powders at 700℃resulted in the formation of HAp/MgTiO_(3)-MgO nanocomposite.X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),and energy dispersive X-ray spectroscopy(EDX)techniques were utilized to characterize the synthesized powders.The results revealed that the dominant phases after mechanical activation were hydroxyapatite,anatase(TiO_(2))and periclase(MgO);while after thermal annealing process at 700℃,hydroxyapatite along with geikielite(MgTiO_(3))and periclase(MgO)were the major phases.Based on the XRD analysis,the evaluation of structural features of the samples indicated that the average crystallite sizes of hydroxyapatite after 10 h of milling and subsequent thermal treatment at 700℃were about 21 nm and 34 nm,respectively.Microscopic observations illustrated that the synthesized powders contained large agglomerates which consisted of significantly finer particles with spheroidal morphology.It is concluded that the mechanothermal method can be used to produce hydroxyapatite-based nanocomposite with appropriate structural and morphological features.展开更多
基金financial support of this work by the University of Tehran and the Iran Nanotechnology Initiative Council
文摘In this paper, the Taguchi method with an L9（34） orthogonal array was used as experimental design to determine the optimum conditions for preparing ZnO nanoparticles via a mechanothermal route. ZnSO4·H20 and NaECO3 were used as starting materials. The effects of milling time, NaECO3/ZnSO·H20 molar ratio, and ball-to-powder mass ratio （BPR） on the bandgap （Eg） of ZnO nanoparticles were inves- tigated. The ranges of the investigated experimental conditions were 5-15 h for the milling time （t）, 1.0-1.2 for the Na2COa/ZnSO4·H20 mo- lar ratio （M）, and 10-30 for BPR. The milling time and BPR exhibited significant effects; an increase in milling time reduced the bandgap. The optimum conditions from this study were t3 = 15 h, M1 = l, and BPR2 = 20. Only two significant factors （t3, 15 h; BPR2, 20） were used to estimate the performance at the optimum conditions. The calculated bandgap was 3.12 eV, in reasonable agreement with the experimental results obtained under the optimized conditions.
文摘Nanostructures of boron nitride (BN) including nanotubes, nanofibers and nanosheets having a large surface area are very useful in storing hydrogen and other gases. In the present paper we report the synthesis and characterization of these nanostructures of BN using mechanothermal process. Under this process elemental boron powder is first ball milled to about 50 h in an inert atmosphere and then annealed at 1100℃ - 1250℃ for 6 h in the presence of NH3 gas. By this treatment nanotubes and other nanostructures of BN were synthesized. The diameter of BN nanotubes varied from 20 to 50 nm and most of them exhibited spindle or bamboo like morphology. Because of the large surface area, these nanotubes may be explored for a better hydrogen gas storage device as compared to the crystallized nanotubes. The main advantage of this technique is that the nanotubes can be grown in large quantity. A possible growth mechanism towards the evolution of such fascinating nano-objects of boron nitride has been discussed employing high-resolution transmission electron microscopy and photoluminescence.
基金This work was financially supported by the National High Technology Research and Development Program of China （Grant No. 2011AA06A102）, the National Natural Science Foundation ofChina （Grant No. 21306053）, the Key Project of Scientific Research Innovation of Shanghai Municipal Education Commission （Grant No. 14ZZ063）, and the Fundamental Research Fund for the Central Universities （WB1213008）.
文摘The process of order to recover aluminum investigated. The CS was activating coal spoil （CS） in as a high value product was first characterized by X-ray fluorescence （XRF）, X-ray diffraction （XRD） and thermo- gravimetric analysis-differential scanning calorimetry （TGA-DSC） in order to determine the chemical and mineral compositions of the CS. Then a mechanothermal activation method was adopted to increase the aluminum activity in the coal spoil. Over 95% of the aluminum in the CS could be extracted using this activation method. The mechanothermal activation process promoted the destruc- tion of kaolinite structures and hindered the formation of amorphous γ-Al2O3. This resulted in a high aluminum leaching activity in the mechanothermally activated CS.
基金research affairs of Islamic Azad University,Najafabad Branch,for supporting this research.
文摘Hydroxyapatite-magnesium titanate composite nanopowders have been developed using a mechanothermal process.Thermal treatment of the milled powders at 700℃resulted in the formation of HAp/MgTiO_(3)-MgO nanocomposite.X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),and energy dispersive X-ray spectroscopy(EDX)techniques were utilized to characterize the synthesized powders.The results revealed that the dominant phases after mechanical activation were hydroxyapatite,anatase(TiO_(2))and periclase(MgO);while after thermal annealing process at 700℃,hydroxyapatite along with geikielite(MgTiO_(3))and periclase(MgO)were the major phases.Based on the XRD analysis,the evaluation of structural features of the samples indicated that the average crystallite sizes of hydroxyapatite after 10 h of milling and subsequent thermal treatment at 700℃were about 21 nm and 34 nm,respectively.Microscopic observations illustrated that the synthesized powders contained large agglomerates which consisted of significantly finer particles with spheroidal morphology.It is concluded that the mechanothermal method can be used to produce hydroxyapatite-based nanocomposite with appropriate structural and morphological features.
