The bulk electronic structure of kaolinite (001) plane was studied with quantum mechanical calculations. The CASTEP parameterization of ultrasoft pseudopotentials without core corrections was used to optimize the stru...The bulk electronic structure of kaolinite (001) plane was studied with quantum mechanical calculations. The CASTEP parameterization of ultrasoft pseudopotentials without core corrections was used to optimize the structure of kaolinite bulk and slab models. The results show that Fermi energy of kaolinite (001) plane is 3.05 eV, and the band gap is 4.52 eV. The partial density of states (PDOS) of kaolinite (001) plane indicates that Al-O and Si-O bonds on the mineral surface are highly polar. The oxygen atoms of hydroxyl groups in surface layer are capable of forming hydrogen bond with the head group of cationic collectors. The properties of dodecylamine (DDA) cation were also calculated by density function theory (DFT) method at B3LYP/6-31G (d) level for illuminating the flotation processes of kaolinite. Besides the electrostatic attraction, the mechanism between kaolinite and DDA is found to be hydrogen bonds under acidic condition.展开更多
The variation of interlayer coupling can greatly affect the bandstructure of few layered transition metal dichalcogenides(TMDs),for instance,transition of indirect-to-direct bandgap and vice versa,which is correlated ...The variation of interlayer coupling can greatly affect the bandstructure of few layered transition metal dichalcogenides(TMDs),for instance,transition of indirect-to-direct bandgap and vice versa,which is correlated with the charge carrier and optical density.However,methods that can modulate the coupling strength in a controllable way are still lacking.Here,we report a fluidic dynamic strategy to tune the interlayer coupling of folded bi-layer MoS_(2).By controlling the flow direction and particle size of the fluid,mono-layer MoS_(2)can be folded into bi-layer with a controlled folding direction for designated twist angles as well as tunable interlayer coupling.Compared with normally folded bi-layer MoS_(2),the photoluminescence(PL)peak of the direct-bandgap transition for folded bi-layer MoS_(2)by fluid flow is weakened accompanied with the re-appearance of indirect-bandgap transition peak.Besides,the fluid flow creates a clear trajectory on the folded MoS_(2),exhibiting various degrees of interlayer coupling along it.Field-effect transistors(FETs)were further fabricated on tunably coupled folded-bi-layers,proving that the bandstructure and electrical property is strongly correlated with the degree of interlayer coupling.This fluidic dynamic strategy can be extended to other TMDs on any substrate,and together with its excellent capability in controlled interlayer coupling,it will provide a new way for the development of TMDs optoelectronics.展开更多
This paper performs first-principles calculations to study the structural, mechanical and electronic properties of the spinels ZnA1204, ZnGa2O4 and ZnCr2O4, using density functional theory with the plane-wave pseudopo...This paper performs first-principles calculations to study the structural, mechanical and electronic properties of the spinels ZnA1204, ZnGa2O4 and ZnCr2O4, using density functional theory with the plane-wave pseudopotential method. Our calculations are in good agreement with previous theoretical calculations and the available experimental data. The studies in this paper focus on the evolution of the mechanical properties of ZnAl2O4, ZnGa2O4 and ZnCr2O4 under hydrostatic pressure. The results show that the cubic phases of ZnAl2O4, ZnCa2O4 and ZnCr2O4 become unstable at about 50 GPa, 40 GPa and 25 GPa, respectively. From analysis of the band structure of the three compounds at equilibrium volume, it obtains a direct band gap of 4.35 eV for ZnA1204 and 0.89 cV for ZnCr2O4, while ZnGa2O4 has an indirect band gap of 2.73 eV.展开更多
In this paper, we present the study of band structure relativistically. Here, Dirac equation is formulated from Hamilto-nian in which the formulation is found to contain a correction term known as spin-orbit coupling ...In this paper, we present the study of band structure relativistically. Here, Dirac equation is formulated from Hamilto-nian in which the formulation is found to contain a correction term known as spin-orbit coupling given as that modifies the non-relativistic expression for the same formulation. This term leads to double spin-degeneracy within the first Brillioun zone which is a concept that is not found in other method of study of band structure of material.展开更多
基金Project(2005CB623701) supported by the Major State Basic Research and Development Program of ChinaProject(50874118) supported by the National Nature Science Foundation of ChinaProject(2007B52) supported by the Foundation for the Author of National Excellent Doctoral Dissertation of China
文摘The bulk electronic structure of kaolinite (001) plane was studied with quantum mechanical calculations. The CASTEP parameterization of ultrasoft pseudopotentials without core corrections was used to optimize the structure of kaolinite bulk and slab models. The results show that Fermi energy of kaolinite (001) plane is 3.05 eV, and the band gap is 4.52 eV. The partial density of states (PDOS) of kaolinite (001) plane indicates that Al-O and Si-O bonds on the mineral surface are highly polar. The oxygen atoms of hydroxyl groups in surface layer are capable of forming hydrogen bond with the head group of cationic collectors. The properties of dodecylamine (DDA) cation were also calculated by density function theory (DFT) method at B3LYP/6-31G (d) level for illuminating the flotation processes of kaolinite. Besides the electrostatic attraction, the mechanism between kaolinite and DDA is found to be hydrogen bonds under acidic condition.
基金National Natural Science Foundation of China(Nos.21903007 and 22072006)Young Thousand Talents Program(No.110532103)+2 种基金Beijing Normal University Startup funding(No.312232102)the Fundamental Research Funds for the Central Universities(No.310421109)Double First Class General Science and Technology Projects from School of Chemistry and Chemical Engineering,Shihezi University(No.SHYL-YB201903).
文摘The variation of interlayer coupling can greatly affect the bandstructure of few layered transition metal dichalcogenides(TMDs),for instance,transition of indirect-to-direct bandgap and vice versa,which is correlated with the charge carrier and optical density.However,methods that can modulate the coupling strength in a controllable way are still lacking.Here,we report a fluidic dynamic strategy to tune the interlayer coupling of folded bi-layer MoS_(2).By controlling the flow direction and particle size of the fluid,mono-layer MoS_(2)can be folded into bi-layer with a controlled folding direction for designated twist angles as well as tunable interlayer coupling.Compared with normally folded bi-layer MoS_(2),the photoluminescence(PL)peak of the direct-bandgap transition for folded bi-layer MoS_(2)by fluid flow is weakened accompanied with the re-appearance of indirect-bandgap transition peak.Besides,the fluid flow creates a clear trajectory on the folded MoS_(2),exhibiting various degrees of interlayer coupling along it.Field-effect transistors(FETs)were further fabricated on tunably coupled folded-bi-layers,proving that the bandstructure and electrical property is strongly correlated with the degree of interlayer coupling.This fluidic dynamic strategy can be extended to other TMDs on any substrate,and together with its excellent capability in controlled interlayer coupling,it will provide a new way for the development of TMDs optoelectronics.
基金supported by the Open Research Fund of the State Key Laboratory Breeding Base of Green Chemistry Synthesis Technology (Grant No. GCTKF2010017)the National Basic Research Program of China (Grant No. 2010CB731600)
文摘This paper performs first-principles calculations to study the structural, mechanical and electronic properties of the spinels ZnA1204, ZnGa2O4 and ZnCr2O4, using density functional theory with the plane-wave pseudopotential method. Our calculations are in good agreement with previous theoretical calculations and the available experimental data. The studies in this paper focus on the evolution of the mechanical properties of ZnAl2O4, ZnGa2O4 and ZnCr2O4 under hydrostatic pressure. The results show that the cubic phases of ZnAl2O4, ZnCa2O4 and ZnCr2O4 become unstable at about 50 GPa, 40 GPa and 25 GPa, respectively. From analysis of the band structure of the three compounds at equilibrium volume, it obtains a direct band gap of 4.35 eV for ZnA1204 and 0.89 cV for ZnCr2O4, while ZnGa2O4 has an indirect band gap of 2.73 eV.
文摘In this paper, we present the study of band structure relativistically. Here, Dirac equation is formulated from Hamilto-nian in which the formulation is found to contain a correction term known as spin-orbit coupling given as that modifies the non-relativistic expression for the same formulation. This term leads to double spin-degeneracy within the first Brillioun zone which is a concept that is not found in other method of study of band structure of material.
