By employing the first-principles pseudopotential plane-wave method, the physical properties of zincblende ZnO are investigated in comparison with those of the common wurtzite structure. Zincblende ZnO is predicted to...By employing the first-principles pseudopotential plane-wave method, the physical properties of zincblende ZnO are investigated in comparison with those of the common wurtzite structure. Zincblende ZnO is predicted to be a direct gap semiconductor. Compared to the wurtzite structure, the zincblende ZnO is characterized by smaller bandgap and pressure coefficient, larger electron effective mass, increasing static dielectric constants and more covalent bonding. Furthermore, the optical properties including dielectric function and energy loss function of zincblende ZnO were obtained and analysed with some features. These aspects reveal promising applications of zincblende ZnO in optoelectronic devices.展开更多
The Voronoi structural evolution of silicon upon melting is investigated using a molecular dynamics simulation.At temperatures below the melting point,the solid state system is identified to have a four-fold coordinat...The Voronoi structural evolution of silicon upon melting is investigated using a molecular dynamics simulation.At temperatures below the melting point,the solid state system is identified to have a four-fold coordination structure(4,0,0,0).As the temperature increases,the five−fold coordination(2,3,0,0)and six−fold coordination structures(2,2,2,0)and(0,6,0,0)are observed.This is explained in terms of increasing atomic displacement due to thermal motion and the trapping of the moving atoms by others.At temperatures above the melting point,nearly all of the four-fold coordination structures grows into multiple-fold coordination ones.展开更多
A remarkable enhancement in room-temperature compressive deformability is realized by the minor-addition of 1.5 at.%Al in ZrTi-based bulk metallic glass.Two amorphous phases are observed by transmission electron micro...A remarkable enhancement in room-temperature compressive deformability is realized by the minor-addition of 1.5 at.%Al in ZrTi-based bulk metallic glass.Two amorphous phases are observed by transmission electron microscopy in the Al-containing alloys and this explains the improvement of compression deformability.The studies suggest that phase separation might occur in glass forming alloys with a negative enthalpy of mixing.展开更多
Molecular dynamics simulation is used to investigate the relationship between Voronoi entropy and viscosity for rapid solidification processing of Zr36Cu64 binary alloy melt. The simulation results at different temper...Molecular dynamics simulation is used to investigate the relationship between Voronoi entropy and viscosity for rapid solidification processing of Zr36Cu64 binary alloy melt. The simulation results at different temperatures, cooling rates, and pressures, show that Voronoi entropy is able to accurately describe the relationship of the transition between the cluster structure and the viscosity of Zr36Cu64 binary alloy melt through Voronoi polyhedron analysis. That is, the higher the degree of order of the microstructure, the lower the Voronoi entropy is and the higher the viscosity is. The simulation provides an important reference for studying metallic glass with high glass-forming ability.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No 50325103, and the National Basic Research Programme of China under Grant No 2005Ct3724404.
文摘By employing the first-principles pseudopotential plane-wave method, the physical properties of zincblende ZnO are investigated in comparison with those of the common wurtzite structure. Zincblende ZnO is predicted to be a direct gap semiconductor. Compared to the wurtzite structure, the zincblende ZnO is characterized by smaller bandgap and pressure coefficient, larger electron effective mass, increasing static dielectric constants and more covalent bonding. Furthermore, the optical properties including dielectric function and energy loss function of zincblende ZnO were obtained and analysed with some features. These aspects reveal promising applications of zincblende ZnO in optoelectronic devices.
基金Supported by the National Natural Science Foundation of China under Grant No 50731005, the National Key Basic Research Programme of China under Grant Nos 2006CB605201 and 2007CB616915, and PCSIRT under Grant No IRT0650.
基金by the National Natural Science Foundation of China under Grant Nos 50771090,50821001 and 51002130.
文摘The Voronoi structural evolution of silicon upon melting is investigated using a molecular dynamics simulation.At temperatures below the melting point,the solid state system is identified to have a four-fold coordination structure(4,0,0,0).As the temperature increases,the five−fold coordination(2,3,0,0)and six−fold coordination structures(2,2,2,0)and(0,6,0,0)are observed.This is explained in terms of increasing atomic displacement due to thermal motion and the trapping of the moving atoms by others.At temperatures above the melting point,nearly all of the four-fold coordination structures grows into multiple-fold coordination ones.
基金Supported by the National Natural Science Foundation of China under Grant Nos 50731005,50821001 and 50944029the Natural Science Foundation of Hebei Province under Grant No E2010001176.
文摘A remarkable enhancement in room-temperature compressive deformability is realized by the minor-addition of 1.5 at.%Al in ZrTi-based bulk metallic glass.Two amorphous phases are observed by transmission electron microscopy in the Al-containing alloys and this explains the improvement of compression deformability.The studies suggest that phase separation might occur in glass forming alloys with a negative enthalpy of mixing.
基金Project supported by the National Basic Research Program of China(Grant No.2013CB733000)the National Natural Science Foundation of China(Grant Nos.51271161 and 51271162)
文摘Molecular dynamics simulation is used to investigate the relationship between Voronoi entropy and viscosity for rapid solidification processing of Zr36Cu64 binary alloy melt. The simulation results at different temperatures, cooling rates, and pressures, show that Voronoi entropy is able to accurately describe the relationship of the transition between the cluster structure and the viscosity of Zr36Cu64 binary alloy melt through Voronoi polyhedron analysis. That is, the higher the degree of order of the microstructure, the lower the Voronoi entropy is and the higher the viscosity is. The simulation provides an important reference for studying metallic glass with high glass-forming ability.
