Single-crystalline orthorhombic antimony trioxide(Sb_(2)O_(3))nanobelts with unique elliptical cross sections and purple-blue photoluminescence have been synthesized.The uniform Sb2O3 nanobelts are 400600 nm in width,...Single-crystalline orthorhombic antimony trioxide(Sb_(2)O_(3))nanobelts with unique elliptical cross sections and purple-blue photoluminescence have been synthesized.The uniform Sb2O3 nanobelts are 400600 nm in width,2040 nm in thickness at the center and gradually become thinner to form sharp edges sub-5 nm in size,tens of micrometers in length,and with[001]as the preferential growth direction.Self-assembly of tens of nanobelts into three-dimensional(3-D)flower-like nanostructures has been observed.Analysis was performed by X-ray diffraction,energy-dispersive X-ray spectroscopy,X-ray photoelectron spectroscopy,scanning electron microscopy,high-resolution transmission electron microscopy,selected area electron diffraction,Raman spectroscopy,Fourier transform infrared spectroscopy,and photoluminescence spectroscopy.The Sb_(2)O_(3) nanobelts display intense purple-blue photoluminescence centred at 425 nm(~2.92 eV).The successful synthesis of nanobelts with elliptical cross sections may cast new light on the investigation of the property differences between nanobelts with rectangular cross sections and those with other cross section geometries.The Sb2O3 nanobelts can be used as effective purple-blue light emitters and may also be valuable for future nanodevice design.展开更多
Abstract The aerodynamic characteristics of elliptic airfoil are quite different from the case of con ventional airfoil for Reynolds number varying from about 104 to 106. In order to reveal the funda mental mechanism,...Abstract The aerodynamic characteristics of elliptic airfoil are quite different from the case of con ventional airfoil for Reynolds number varying from about 104 to 106. In order to reveal the funda mental mechanism, the unsteady flow around a stationary two-dimensional elliptic airfoil with 16% relative thickness has been simulated using unsteady Reynolds-averaged NavieStokes equations and the 7 Reot transition turbulence model at different angles of attack for flow Reynolds number of 5 x 10^5. The aerodynamic coefficients and the pressure distribution obtained by computation are in good agreement with experimental data, which indicates that the numerical method works well. Through this study, the mechanism of the unconventional aerodynamic characteristics of airfoil is analyzed and discussed based on the computational predictions coupled with the wind tunnel results. It is considered that the boundary layer transition at the leading edge and the unsteady flow separation vortices at the trailing edge are the causes of the case. Furthermore, a valuable insight into the physics of how the flow behavior affects the elliptic airfoil＇s aerodynamics is provided.展开更多
基金We are grateful to Fee Li Lie at the University of Arizona for help with the XPS characterization and for financial support from the National Natural Science Foundation of China(Nos.60736001,60572031,and 20571080)Science Foundation Arizona(Strategic Research Group Program).
文摘Single-crystalline orthorhombic antimony trioxide(Sb_(2)O_(3))nanobelts with unique elliptical cross sections and purple-blue photoluminescence have been synthesized.The uniform Sb2O3 nanobelts are 400600 nm in width,2040 nm in thickness at the center and gradually become thinner to form sharp edges sub-5 nm in size,tens of micrometers in length,and with[001]as the preferential growth direction.Self-assembly of tens of nanobelts into three-dimensional(3-D)flower-like nanostructures has been observed.Analysis was performed by X-ray diffraction,energy-dispersive X-ray spectroscopy,X-ray photoelectron spectroscopy,scanning electron microscopy,high-resolution transmission electron microscopy,selected area electron diffraction,Raman spectroscopy,Fourier transform infrared spectroscopy,and photoluminescence spectroscopy.The Sb_(2)O_(3) nanobelts display intense purple-blue photoluminescence centred at 425 nm(~2.92 eV).The successful synthesis of nanobelts with elliptical cross sections may cast new light on the investigation of the property differences between nanobelts with rectangular cross sections and those with other cross section geometries.The Sb2O3 nanobelts can be used as effective purple-blue light emitters and may also be valuable for future nanodevice design.
基金financially supported by National Natural Science Foundation of China(No.11372254)
文摘Abstract The aerodynamic characteristics of elliptic airfoil are quite different from the case of con ventional airfoil for Reynolds number varying from about 104 to 106. In order to reveal the funda mental mechanism, the unsteady flow around a stationary two-dimensional elliptic airfoil with 16% relative thickness has been simulated using unsteady Reynolds-averaged NavieStokes equations and the 7 Reot transition turbulence model at different angles of attack for flow Reynolds number of 5 x 10^5. The aerodynamic coefficients and the pressure distribution obtained by computation are in good agreement with experimental data, which indicates that the numerical method works well. Through this study, the mechanism of the unconventional aerodynamic characteristics of airfoil is analyzed and discussed based on the computational predictions coupled with the wind tunnel results. It is considered that the boundary layer transition at the leading edge and the unsteady flow separation vortices at the trailing edge are the causes of the case. Furthermore, a valuable insight into the physics of how the flow behavior affects the elliptic airfoil＇s aerodynamics is provided.
