Scattering noises in four kinds of lithium niobate crystals with the same double doping system, which are LiNbO3:Fe:Mn, LiNbO3:Ce:Mn, LiNbO3:Ce:Cu, and LiNbO3:Fe:Cu, are observed and compared experimentally. The resul...Scattering noises in four kinds of lithium niobate crystals with the same double doping system, which are LiNbO3:Fe:Mn, LiNbO3:Ce:Mn, LiNbO3:Ce:Cu, and LiNbO3:Fe:Cu, are observed and compared experimentally. The results show that nonvolatile holographic recording can effectively suppress scattering noise, which mainly depends on recombination coefficients of both the shallower centers and the deeper centers. The small recombination coefficients of the shallower centers and the large recombination coefficients of the deeper centers benefit the amplification of the signal gratings and the suppression of the noise gratings. In addition, the initial seed scattering also impacts the recorded scattering noise, and the little seed scattering results in low scattering noise. The theoretical simulations are performed for confirmation. Among the four kinds of doubly doped crystals, in LiNbO3:Ce:Cu the performances of nonvolatile recording are the best with low scattering noise and high diffraction efficiency.展开更多
By using spin-polarized density functional theory calculations, the electron density differences, band structures and density of states of p-type N-doped PbTiO3 have been studied. In addition, the oxygen vacancy in N-...By using spin-polarized density functional theory calculations, the electron density differences, band structures and density of states of p-type N-doped PbTiO3 have been studied. In addition, the oxygen vacancy in N-doped PbTiO3 is also discussed. After the nitrogen dopant is introduced into the crystal, the N-doped PbTiO3 system is spin-polarized, the spin-down valance bands move to a high energy level and the Fermi energy level moves to the top of the valance bands, finally the band gap is narrowed. In this process, the N-doped PbTiO3 shows typical p-type semiconductor characteristics. When an oxygen vacancy and N impurity coexist in PbTiO3, there is no spin-polarized phenomenon. The conduction bands move downward and the acceptors are found to be fully compensated. The calculation results are mostly consistent with the experimental data.展开更多
Defect formation energies, electronic structures and optical properties of Sn-doped β-GazO3, F-doped β-Ga2O3, and Sn/F co-doped β-Ga2O3 were calculated using the first-principles. The calculated results of the pure...Defect formation energies, electronic structures and optical properties of Sn-doped β-GazO3, F-doped β-Ga2O3, and Sn/F co-doped β-Ga2O3 were calculated using the first-principles. The calculated results of the pure and Sn-doped β-Ga2O3 using the local-density approximation （LDA） method show that the lattice parameters and electronic structures are in agreement with previous data. The defect formation energies demonstrate that the doped systems are relatively easy to form under O-rich conditions. Sn-doping, F-doping and Sn/F co-doping make β-Ga2O3 become an n-type semiconductor. Sn/F co-doping β-Ga2O3 has the smallest effective electron mass and the biggest relative electron number, which is expected to possess good conductivity. Sn/F co-doping β-Ga2O3 displays an intense absorption in visible light.展开更多
In this Letter, new concepts of fluorescence phase-change materials and fluorescence phase-change multilevel recording are proposed. High-contrast fluorescence between the amorphous and crystalline states is achieved ...In this Letter, new concepts of fluorescence phase-change materials and fluorescence phase-change multilevel recording are proposed. High-contrast fluorescence between the amorphous and crystalline states is achieved in nickel- or bismuth-doped Ge;Sb;Te;phase-change memory thin films. Opposite phase-selective fluorescence effects are observed when different doping ions are used. The fluorescence intensity is sensitive to the crystallization degree of the films. This characteristic can be applied in reconfigurable multi-state memory and other logic devices. It also has likely applications in display and data visualization.展开更多
Layers of transparent and conductive Sn-doped zinc oxide (ZnO) have been prepared using chemical reactive liquid phase (spray) method on glass substrates. X-ray diffraction analysis shows that the obtained layers show...Layers of transparent and conductive Sn-doped zinc oxide (ZnO) have been prepared using chemical reactive liquid phase (spray) method on glass substrates. X-ray diffraction analysis shows that the obtained layers show preferential grains orientation along the direction (002). Microstructural analysis indicates that the thickness of the deposited films is independent of Sn content, i.e. 408 nm, and that the average grain size increases with increasing Sn content, ranging from 31 nm to 42 nm. The value of the optical gap obtained using UV-visible transmission spectroscopy method increases slightly from 3.1 eV to 3.3 eV. Moreover, transmission curves reveal that the prepared thin films are transparent in the visible domain.展开更多
The n-type Nb-doped SrTiO3 with different doping concentrations were studied by first principles cal- culations. The effects of Nb concentration on the formation enthalpy, electronic structure and optical property wer...The n-type Nb-doped SrTiO3 with different doping concentrations were studied by first principles cal- culations. The effects of Nb concentration on the formation enthalpy, electronic structure and optical property were investigated. Results show that Nb preferentially enters the Ti site in SrTiO3, which is in good agreement with the experimental observation. The Fermi level of Nb-doped SrTiO3 moves into the bottom of the conduction band, and the system becomes an n-type semiconductor. The effect of Nb-doping concentration on the conductivity was discussed from the microscopic point of view. Furthermore, the 1.11 at% Nb-doped SrTiO3 shows strong absorp- tion in the visible light and becomes a very useful material for photo-catalytic activity. The 1.67 at% and 2.5 at% Nb-doped models will be potential transparent conductive materials.展开更多
The p-type N-doped PbTiO3 with different doping concentrations have been studied by first-principles calculations. The charge density differences, band structures, density of states and optical properties have been in...The p-type N-doped PbTiO3 with different doping concentrations have been studied by first-principles calculations. The charge density differences, band structures, density of states and optical properties have been investigated. After an oxygen atom is substituted by a nitrogen atom in the crystals, the valance bands move to high energy levels and the Fermi energy level gets into the top of the valance bands. Results show that the values of the band gaps are decreased and the stability is weakened when the N concentration increases. The 2.5 at% N-doped PbTiO3 shows the best p-type conductivity and the visible-light absorption can be enhanced most at this doping concentration, which is necessary in semiconductors or photocatalysts.展开更多
AlPO4-SiO2 films doped with Rhodamine 6G （Rh6G） are prepared using the sol-gel dip-coating method. The surface morphology is characterized by atomic force microscopy. The results indicate that the surface morphology...AlPO4-SiO2 films doped with Rhodamine 6G （Rh6G） are prepared using the sol-gel dip-coating method. The surface morphology is characterized by atomic force microscopy. The results indicate that the surface morphology of the films is not significantly affected by the amount of dyes loaded. The absorption and excitation spectra indicate low aggregation even at a Rh6G doping concentration of 1.0×10-3 mol/L. Efficient fluorescence with a band centered at 553 nm is observed.展开更多
文摘Scattering noises in four kinds of lithium niobate crystals with the same double doping system, which are LiNbO3:Fe:Mn, LiNbO3:Ce:Mn, LiNbO3:Ce:Cu, and LiNbO3:Fe:Cu, are observed and compared experimentally. The results show that nonvolatile holographic recording can effectively suppress scattering noise, which mainly depends on recombination coefficients of both the shallower centers and the deeper centers. The small recombination coefficients of the shallower centers and the large recombination coefficients of the deeper centers benefit the amplification of the signal gratings and the suppression of the noise gratings. In addition, the initial seed scattering also impacts the recorded scattering noise, and the little seed scattering results in low scattering noise. The theoretical simulations are performed for confirmation. Among the four kinds of doubly doped crystals, in LiNbO3:Ce:Cu the performances of nonvolatile recording are the best with low scattering noise and high diffraction efficiency.
基金supported by the National Natural Science Foundation of China(No.10974077)the Innovation Project of Shandong Graduate Education,China(No.SDYY13093)
文摘By using spin-polarized density functional theory calculations, the electron density differences, band structures and density of states of p-type N-doped PbTiO3 have been studied. In addition, the oxygen vacancy in N-doped PbTiO3 is also discussed. After the nitrogen dopant is introduced into the crystal, the N-doped PbTiO3 system is spin-polarized, the spin-down valance bands move to a high energy level and the Fermi energy level moves to the top of the valance bands, finally the band gap is narrowed. In this process, the N-doped PbTiO3 shows typical p-type semiconductor characteristics. When an oxygen vacancy and N impurity coexist in PbTiO3, there is no spin-polarized phenomenon. The conduction bands move downward and the acceptors are found to be fully compensated. The calculation results are mostly consistent with the experimental data.
基金supported by the National Natural Science Foundation of China(No.10974077)the Innovation Project of Shandong Graduate Education,China(No.SDYY13093)
文摘Defect formation energies, electronic structures and optical properties of Sn-doped β-GazO3, F-doped β-Ga2O3, and Sn/F co-doped β-Ga2O3 were calculated using the first-principles. The calculated results of the pure and Sn-doped β-Ga2O3 using the local-density approximation （LDA） method show that the lattice parameters and electronic structures are in agreement with previous data. The defect formation energies demonstrate that the doped systems are relatively easy to form under O-rich conditions. Sn-doping, F-doping and Sn/F co-doping make β-Ga2O3 become an n-type semiconductor. Sn/F co-doping β-Ga2O3 has the smallest effective electron mass and the biggest relative electron number, which is expected to possess good conductivity. Sn/F co-doping β-Ga2O3 displays an intense absorption in visible light.
基金partially supported by the National Natural Science Foundation of China(Nos.61178059,51472258,and 61137002)the National Basic Research Program of China(No.2013CBA01900)
文摘In this Letter, new concepts of fluorescence phase-change materials and fluorescence phase-change multilevel recording are proposed. High-contrast fluorescence between the amorphous and crystalline states is achieved in nickel- or bismuth-doped Ge;Sb;Te;phase-change memory thin films. Opposite phase-selective fluorescence effects are observed when different doping ions are used. The fluorescence intensity is sensitive to the crystallization degree of the films. This characteristic can be applied in reconfigurable multi-state memory and other logic devices. It also has likely applications in display and data visualization.
文摘Layers of transparent and conductive Sn-doped zinc oxide (ZnO) have been prepared using chemical reactive liquid phase (spray) method on glass substrates. X-ray diffraction analysis shows that the obtained layers show preferential grains orientation along the direction (002). Microstructural analysis indicates that the thickness of the deposited films is independent of Sn content, i.e. 408 nm, and that the average grain size increases with increasing Sn content, ranging from 31 nm to 42 nm. The value of the optical gap obtained using UV-visible transmission spectroscopy method increases slightly from 3.1 eV to 3.3 eV. Moreover, transmission curves reveal that the prepared thin films are transparent in the visible domain.
基金Project supported by the National Natural Science Foundation of China(No.10974077)the Innovation Project of Shandong Graduate Education,China(No.SDYY13093)
文摘The n-type Nb-doped SrTiO3 with different doping concentrations were studied by first principles cal- culations. The effects of Nb concentration on the formation enthalpy, electronic structure and optical property were investigated. Results show that Nb preferentially enters the Ti site in SrTiO3, which is in good agreement with the experimental observation. The Fermi level of Nb-doped SrTiO3 moves into the bottom of the conduction band, and the system becomes an n-type semiconductor. The effect of Nb-doping concentration on the conductivity was discussed from the microscopic point of view. Furthermore, the 1.11 at% Nb-doped SrTiO3 shows strong absorp- tion in the visible light and becomes a very useful material for photo-catalytic activity. The 1.67 at% and 2.5 at% Nb-doped models will be potential transparent conductive materials.
基金Project supported by the National Natural Science Foundation of China(No.10974077)the Innovation Project of Shandong Graduate Education,China(No.SDYY13093)
文摘The p-type N-doped PbTiO3 with different doping concentrations have been studied by first-principles calculations. The charge density differences, band structures, density of states and optical properties have been investigated. After an oxygen atom is substituted by a nitrogen atom in the crystals, the valance bands move to high energy levels and the Fermi energy level gets into the top of the valance bands. Results show that the values of the band gaps are decreased and the stability is weakened when the N concentration increases. The 2.5 at% N-doped PbTiO3 shows the best p-type conductivity and the visible-light absorption can be enhanced most at this doping concentration, which is necessary in semiconductors or photocatalysts.
基金supported by the National Natural Science Foundation of China(Nos.50802103 and 51072207)the Natural Science Foundation of Shanghai(No.11ZR1441500)
文摘AlPO4-SiO2 films doped with Rhodamine 6G （Rh6G） are prepared using the sol-gel dip-coating method. The surface morphology is characterized by atomic force microscopy. The results indicate that the surface morphology of the films is not significantly affected by the amount of dyes loaded. The absorption and excitation spectra indicate low aggregation even at a Rh6G doping concentration of 1.0×10-3 mol/L. Efficient fluorescence with a band centered at 553 nm is observed.
