The electronic property of pyrite supercell containing As,Se,Te,Co or Ni hetero atoms were calculated using density functional theory（DFT）,and the reactivities of pyrite with oxygen and xanthate were discussed by fr...The electronic property of pyrite supercell containing As,Se,Te,Co or Ni hetero atoms were calculated using density functional theory（DFT）,and the reactivities of pyrite with oxygen and xanthate were discussed by frontier orbital methods.The cell volume expands due to the presence of impurity.Co and Ni mainly affect the bands near Fermi levels,while As mainly affects the shallow and deep valence bands,and Se and Te mainly affect the deep valence bands.Electronic density analysis suggests that there exists a strong covalent interaction between hetero atom and its surrounding atoms.By frontier orbital calculation,it is suggested that As,Co and Ni have greater influence on the HOMO and LUMO of pyrite than Se and Te.In addition,pyrite containing As,Co or Ni is easier to oxidize by oxygen than pyrite containing Se or Te,and pyrite containing Co or Ni has greater interaction with collector.These are in agreement with the observed pyrite practice.展开更多
The electronic properties of sphalerite(110)surface bearing Fe,Mn and Cd impurities were calculated using density-functional theory,and the effects of impurities on the copper activation of sphalerite were investigate...The electronic properties of sphalerite(110)surface bearing Fe,Mn and Cd impurities were calculated using density-functional theory,and the effects of impurities on the copper activation of sphalerite were investigated.Calculated results indicate that both Fe and Mn impurities narrow the band gap of sphalerite surface and lead to the Fermi level shifting to conduction band.Impurity levels composed of Fe 3d and Mn 3d orbital appearing in band gap are beneficial to electrons transfer from the valence band to the conduction band and promote the surface conductivity and the electrochemical activity.The results show that Fe and Mn impurities cannot be replaced by Cu atom,which reduces the exchange sites(Zn)for Cu atom,hence Fe-and Mn-bearing sphalerites are hard to be activated by copper.Cd impurity has little effect on electronic structure of sphalerite surface;however,Cd atom is easily replaced by Cu atom,and this is the reason why the Cd-bearing sphalerite can be easily floated.展开更多
The nickel hydroxide prepared by micro-emulsion method was doped by coprecipitated Zn. The effect of the amount of zinc-doped on the properties of Ni(OH)2 such as the reversibility of the electrode reaction, the charg...The nickel hydroxide prepared by micro-emulsion method was doped by coprecipitated Zn. The effect of the amount of zinc-doped on the properties of Ni(OH)2 such as the reversibility of the electrode reaction, the charge efficiency and active material utilization ratio of nickel electrode, and discharge specific capacity was studied by cyclic voltammetry and constant current charge-discharge tests. The results indicate that the specific discharge capacity of nickel hydroxide obtained by micro-emulsion method is much less than its theoretical value because the transfer of electrons and the diffusion of protons H+ are hindered owing to its crystal grain size in a nanometer range and thus possessing higher crystal interface resistance. The crystal cells are swelled and the crystal defects increased in prepared material due to part of Ni2+ substituted by Zn2+ when zinc and nickel hydroxide are coprecipitated. Hence, the electrons and protons H+ in the electrode reaction are transferred easily, the electrochemical behavior of nickel electrode is improved and discharge specific capacity is promoted. However, the performance of Ni(OH)2 is gradually enhanced with the addition of zinc-doped at first, while slowly decreased after the content of zinc is added to a certain value. The best electrode reaction reversibility, the highest electrode charge efficiency, the highest active material utilization ratio and the largest specific capacity on discharge are available when the mass fraction of Zn doped in nickel hydroxide by coprecipitation reaches 2.5 %.展开更多
Electron relaxation time and density of states near the Fermi level were calculated for ＂dirty＂ carbon nanotubes taking into account multiple elastic electrons scattering on impurities and structural inhomogeneities...Electron relaxation time and density of states near the Fermi level were calculated for ＂dirty＂ carbon nanotubes taking into account multiple elastic electrons scattering on impurities and structural inhomogeneities of a short-range order type. A possible explanation of low-temperature behavior of density of states and electrical conductivity depending on defect structure, impurities and chirality is presented.展开更多
The tellurium-based glasses TeO2, 85TeOz-15WO3, 85TeO2-10WO3-5Sm203, 77TeO2-20WO3-3Y203, 77TeO2-20WO3-3La203, 65TeO2-33WO3-2Er203 and 49TeO2-29.4WO3-19.6PbO-2Er203 have been prepared by melt quenching technique. Densi...The tellurium-based glasses TeO2, 85TeOz-15WO3, 85TeO2-10WO3-5Sm203, 77TeO2-20WO3-3Y203, 77TeO2-20WO3-3La203, 65TeO2-33WO3-2Er203 and 49TeO2-29.4WO3-19.6PbO-2Er203 have been prepared by melt quenching technique. Density and molar volume have been measured for the present glasses. Optical absorption studies are carried out on the glass system in the wavelength range of 200-900 nm. The compositions depend on different physical parameters such as density, molar volume and oxygen packing density will be discussed. Also, molar refraction （RM）, calculated refractive index （n）, metallization criterion （M）, electronic polarizability of the oxide ion （to2＂（Eopt） and optical basicity A^opt have been determined.展开更多
The electronic and optical properties of 2D Cu_2Si and Cu_2Si:Ti are investigated based on the density functional theory(DFT) using the FP-LAPW method and GGA approximation. The 2D Cu_2Si has metallic and non magnetic...The electronic and optical properties of 2D Cu_2Si and Cu_2Si:Ti are investigated based on the density functional theory(DFT) using the FP-LAPW method and GGA approximation. The 2D Cu_2Si has metallic and non magnetic properties, whereas adding Ti impurity to its structure changes the electronic behavior to the half-metallic with 3.256μB magnetic moment. The optical transition is not occurred in the infrared and visible area for the 2D Cu_2Si in x-direction and by adding Ti atom, the real part of dielectric function in the x-direction, Re(ε(ω))_x is reached to a Dirac peak at this energy range. Moreover, the absorption gap tends to zero in x-direction of the 2D Cu_2Si:Ti.展开更多
We have investigated the effects of B impurities on the structure and mechanical properties of NiA1 intermetallics by using a first-principles pseudopotential total-energy method, based on the density functional theor...We have investigated the effects of B impurities on the structure and mechanical properties of NiA1 intermetallics by using a first-principles pseudopotential total-energy method, based on the density functional theory with a generalized gradient approximation. We found that the impurity B atoms can either replace Ni atoms or Al atoms or both, depending on the surround- ing environment. We demonstrated that the presence of B will cause an increase in brittleness and a decrease in the ductility of NiAI for the Al-substitutional case, while causing an increase in the ductility of NiAl for the Ni-subtitutional case, based on the calculated elastic constants and the empirical criterions. This indicates that the effects of B impurities on the mechanical prop- erties of NiAl intermetallics are quite composition-dependent.展开更多
基金Project (50864001) supported by the National Natural Science Foundation of China
文摘The electronic property of pyrite supercell containing As,Se,Te,Co or Ni hetero atoms were calculated using density functional theory（DFT）,and the reactivities of pyrite with oxygen and xanthate were discussed by frontier orbital methods.The cell volume expands due to the presence of impurity.Co and Ni mainly affect the bands near Fermi levels,while As mainly affects the shallow and deep valence bands,and Se and Te mainly affect the deep valence bands.Electronic density analysis suggests that there exists a strong covalent interaction between hetero atom and its surrounding atoms.By frontier orbital calculation,it is suggested that As,Co and Ni have greater influence on the HOMO and LUMO of pyrite than Se and Te.In addition,pyrite containing As,Co or Ni is easier to oxidize by oxygen than pyrite containing Se or Te,and pyrite containing Co or Ni has greater interaction with collector.These are in agreement with the observed pyrite practice.
基金Project(50864001) supported by the National Natural Science Foundation of China
文摘The electronic properties of sphalerite(110)surface bearing Fe,Mn and Cd impurities were calculated using density-functional theory,and the effects of impurities on the copper activation of sphalerite were investigated.Calculated results indicate that both Fe and Mn impurities narrow the band gap of sphalerite surface and lead to the Fermi level shifting to conduction band.Impurity levels composed of Fe 3d and Mn 3d orbital appearing in band gap are beneficial to electrons transfer from the valence band to the conduction band and promote the surface conductivity and the electrochemical activity.The results show that Fe and Mn impurities cannot be replaced by Cu atom,which reduces the exchange sites(Zn)for Cu atom,hence Fe-and Mn-bearing sphalerites are hard to be activated by copper.Cd impurity has little effect on electronic structure of sphalerite surface;however,Cd atom is easily replaced by Cu atom,and this is the reason why the Cd-bearing sphalerite can be easily floated.
文摘The nickel hydroxide prepared by micro-emulsion method was doped by coprecipitated Zn. The effect of the amount of zinc-doped on the properties of Ni(OH)2 such as the reversibility of the electrode reaction, the charge efficiency and active material utilization ratio of nickel electrode, and discharge specific capacity was studied by cyclic voltammetry and constant current charge-discharge tests. The results indicate that the specific discharge capacity of nickel hydroxide obtained by micro-emulsion method is much less than its theoretical value because the transfer of electrons and the diffusion of protons H+ are hindered owing to its crystal grain size in a nanometer range and thus possessing higher crystal interface resistance. The crystal cells are swelled and the crystal defects increased in prepared material due to part of Ni2+ substituted by Zn2+ when zinc and nickel hydroxide are coprecipitated. Hence, the electrons and protons H+ in the electrode reaction are transferred easily, the electrochemical behavior of nickel electrode is improved and discharge specific capacity is promoted. However, the performance of Ni(OH)2 is gradually enhanced with the addition of zinc-doped at first, while slowly decreased after the content of zinc is added to a certain value. The best electrode reaction reversibility, the highest electrode charge efficiency, the highest active material utilization ratio and the largest specific capacity on discharge are available when the mass fraction of Zn doped in nickel hydroxide by coprecipitation reaches 2.5 %.
文摘Electron relaxation time and density of states near the Fermi level were calculated for ＂dirty＂ carbon nanotubes taking into account multiple elastic electrons scattering on impurities and structural inhomogeneities of a short-range order type. A possible explanation of low-temperature behavior of density of states and electrical conductivity depending on defect structure, impurities and chirality is presented.
文摘The tellurium-based glasses TeO2, 85TeOz-15WO3, 85TeO2-10WO3-5Sm203, 77TeO2-20WO3-3Y203, 77TeO2-20WO3-3La203, 65TeO2-33WO3-2Er203 and 49TeO2-29.4WO3-19.6PbO-2Er203 have been prepared by melt quenching technique. Density and molar volume have been measured for the present glasses. Optical absorption studies are carried out on the glass system in the wavelength range of 200-900 nm. The compositions depend on different physical parameters such as density, molar volume and oxygen packing density will be discussed. Also, molar refraction （RM）, calculated refractive index （n）, metallization criterion （M）, electronic polarizability of the oxide ion （to2＂（Eopt） and optical basicity A^opt have been determined.
基金Supported by Islamic Azad University,Kermanshah branch,Kermanshah,Iran
文摘The electronic and optical properties of 2D Cu_2Si and Cu_2Si:Ti are investigated based on the density functional theory(DFT) using the FP-LAPW method and GGA approximation. The 2D Cu_2Si has metallic and non magnetic properties, whereas adding Ti impurity to its structure changes the electronic behavior to the half-metallic with 3.256μB magnetic moment. The optical transition is not occurred in the infrared and visible area for the 2D Cu_2Si in x-direction and by adding Ti atom, the real part of dielectric function in the x-direction, Re(ε(ω))_x is reached to a Dirac peak at this energy range. Moreover, the absorption gap tends to zero in x-direction of the 2D Cu_2Si:Ti.
基金supported by the Basic Research Project of High Education (Grant No. ZXH2009C004)the Foundation of CAUC (Grant No. 09QD06X)
文摘We have investigated the effects of B impurities on the structure and mechanical properties of NiA1 intermetallics by using a first-principles pseudopotential total-energy method, based on the density functional theory with a generalized gradient approximation. We found that the impurity B atoms can either replace Ni atoms or Al atoms or both, depending on the surround- ing environment. We demonstrated that the presence of B will cause an increase in brittleness and a decrease in the ductility of NiAI for the Al-substitutional case, while causing an increase in the ductility of NiAl for the Ni-subtitutional case, based on the calculated elastic constants and the empirical criterions. This indicates that the effects of B impurities on the mechanical prop- erties of NiAl intermetallics are quite composition-dependent.
