In the presence of an applied uniform magnetic field Bo, the properties of 2-dimensional （2D） magnetosonic solitary waves of relativistic amplitude in the plasma containing electron, light ions He^＋, and heavy ion...In the presence of an applied uniform magnetic field Bo, the properties of 2-dimensional （2D） magnetosonic solitary waves of relativistic amplitude in the plasma containing electron, light ions He^＋, and heavy ions O＋ are presented. In the weakly relativistic limit, a Kadomtsev Petviashvili （KP） equation is derived by reductive perturbation method. We give the N-soliton solution of the KP equation and find dromion solutions of a potential of the physical field. The interaction law of the dromions is obtained, which shows there is no exchange of energy, momentum, and angular momentum before and after interaction of the dromions except for phase shifts.展开更多
The geometrical structure optimization,band structure,density of states,and charge density contour of potassium niobate(KNbO_(3))in the bulk[100]direction and(100)surface are calculated and analyzed using density func...The geometrical structure optimization,band structure,density of states,and charge density contour of potassium niobate(KNbO_(3))in the bulk[100]direction and(100)surface are calculated and analyzed using density functional theory.The elastic constants,which can describe the bonding characteristics and structural stability,are also computed,and the dielectric function,which can be used to calculate all the other optical properties of the material,is evaluated.Local density approximation functional analysis using CASTEP software is also employed.Several similarities and differences are observed in the properties of the KNbO_(3) bulk and surface.Almost all of the calculated results for the bulk sample are twice those of the surface sample.The results are consistent with the experiment.展开更多
We investigate the luminescence properties of erbium-doped and erbium-ytterbium-codoped potassium lithium tantalate niobate ceramics prepared by the solid phasesyntheses method.The crystalline structure and surface mo...We investigate the luminescence properties of erbium-doped and erbium-ytterbium-codoped potassium lithium tantalate niobate ceramics prepared by the solid phasesyntheses method.The crystalline structure and surface morphology of these ceramics are tested by x-ray diffraction and scanning electron microscopy.The green,red,and near-infrared upconversion photoluminescence properties are analyzed by the steady-state spectra under 975 nm and 800 nm excitations.These ceramics arewell sintered and tetragonal tungsten type crystalline structure with the 4 mm point group and the P4bm space group.The Er3+upconversion emission integrated intensities increase with theincrease in Er3+ion concentration,while the green emissiondecreases with the increase in Yb^(3+)ion concentration under the 800 nm excitation.An effective energy back transfer process from the Er^(3+)^(4)S_(3/2)state to Yb^(3+)ground state plays an important role in enhancing the red emission and weakening the green emission.展开更多
The crystal surface properties of potassium tantalite niobate,KTa_(0.5)Nb_(0.5)O_(3) (KTN),are studied with firstprinciples calculation based on the density functional theory (DFT).Generalized gradient approximation (...The crystal surface properties of potassium tantalite niobate,KTa_(0.5)Nb_(0.5)O_(3) (KTN),are studied with firstprinciples calculation based on the density functional theory (DFT).Generalized gradient approximation (GGA) functional analysis is also employed by using CASTEP software.The explanations for the differences of the ferroelectric and piezoelectric properties between the bulk and surface of the material are provided.The DFT with GGA is used to determine the structure and to calculate the electronic and optical properties of the chemically ordered KTa_(0.5)Nb_(0.5)O_(3) crystal (100),(110) and (111) surfaces.The results show that the surface properties are different from the bulk properties.The data obtained agree with the expected values and can serve as guidance for future experimental studies in the fields of photorefraction and nonlinear optics.展开更多
A slant grating was recorded with two laser beams incident on photorefractive crystal in an external dc electric field.Two-dimensional perturbative analytical solution for the first two-order space-charge field for st...A slant grating was recorded with two laser beams incident on photorefractive crystal in an external dc electric field.Two-dimensional perturbative analytical solution for the first two-order space-charge field for steady-state photorefractive slant grating recording has been obtained.It is shown that the inclusion of the longitudinal component of the space-charge field during photorefractive two-wave coupling can predict reduction of the fundamental harmonic and enhancement or reduction of the second-order harmonic for various applied field strength and various grating slant angles.The dependence of the first two-order harmonics on the slant angle and on the applied field strength is examined.展开更多
基金Supported by National Natural Science Foundation of China under Grant No. 10747109the Research Fund for the Doctoral Program of Higher Education of China under Grant No. 20070008001
文摘In the presence of an applied uniform magnetic field Bo, the properties of 2-dimensional （2D） magnetosonic solitary waves of relativistic amplitude in the plasma containing electron, light ions He^＋, and heavy ions O＋ are presented. In the weakly relativistic limit, a Kadomtsev Petviashvili （KP） equation is derived by reductive perturbation method. We give the N-soliton solution of the KP equation and find dromion solutions of a potential of the physical field. The interaction law of the dromions is obtained, which shows there is no exchange of energy, momentum, and angular momentum before and after interaction of the dromions except for phase shifts.
文摘The geometrical structure optimization,band structure,density of states,and charge density contour of potassium niobate(KNbO_(3))in the bulk[100]direction and(100)surface are calculated and analyzed using density functional theory.The elastic constants,which can describe the bonding characteristics and structural stability,are also computed,and the dielectric function,which can be used to calculate all the other optical properties of the material,is evaluated.Local density approximation functional analysis using CASTEP software is also employed.Several similarities and differences are observed in the properties of the KNbO_(3) bulk and surface.Almost all of the calculated results for the bulk sample are twice those of the surface sample.The results are consistent with the experiment.
基金Supported by the National Natural Science Foundation of China under Grant No 11074059the Fundamental Research Funds for the Central Universities of China under Grant No Bzx/13b101-06.
文摘We investigate the luminescence properties of erbium-doped and erbium-ytterbium-codoped potassium lithium tantalate niobate ceramics prepared by the solid phasesyntheses method.The crystalline structure and surface morphology of these ceramics are tested by x-ray diffraction and scanning electron microscopy.The green,red,and near-infrared upconversion photoluminescence properties are analyzed by the steady-state spectra under 975 nm and 800 nm excitations.These ceramics arewell sintered and tetragonal tungsten type crystalline structure with the 4 mm point group and the P4bm space group.The Er3+upconversion emission integrated intensities increase with theincrease in Er3+ion concentration,while the green emissiondecreases with the increase in Yb^(3+)ion concentration under the 800 nm excitation.An effective energy back transfer process from the Er^(3+)^(4)S_(3/2)state to Yb^(3+)ground state plays an important role in enhancing the red emission and weakening the green emission.
基金Supported by the Science Fund for Distinguished Young Scholars of Heilongjiang Province under Grant No JC200710.
文摘The crystal surface properties of potassium tantalite niobate,KTa_(0.5)Nb_(0.5)O_(3) (KTN),are studied with firstprinciples calculation based on the density functional theory (DFT).Generalized gradient approximation (GGA) functional analysis is also employed by using CASTEP software.The explanations for the differences of the ferroelectric and piezoelectric properties between the bulk and surface of the material are provided.The DFT with GGA is used to determine the structure and to calculate the electronic and optical properties of the chemically ordered KTa_(0.5)Nb_(0.5)O_(3) crystal (100),(110) and (111) surfaces.The results show that the surface properties are different from the bulk properties.The data obtained agree with the expected values and can serve as guidance for future experimental studies in the fields of photorefraction and nonlinear optics.
基金Supported by the Natural Science Foundation of Heilongjiang Province。
文摘A slant grating was recorded with two laser beams incident on photorefractive crystal in an external dc electric field.Two-dimensional perturbative analytical solution for the first two-order space-charge field for steady-state photorefractive slant grating recording has been obtained.It is shown that the inclusion of the longitudinal component of the space-charge field during photorefractive two-wave coupling can predict reduction of the fundamental harmonic and enhancement or reduction of the second-order harmonic for various applied field strength and various grating slant angles.The dependence of the first two-order harmonics on the slant angle and on the applied field strength is examined.
