A series of uniform single-phase spherical BaWO 4:Dy^(3+),Tm^(3+),Eu^(3+)phosphors were prepared via a microwave hydrothermal method by using trisodium citrate dehydrate as surfactant.The phase structure,morphology an...A series of uniform single-phase spherical BaWO 4:Dy^(3+),Tm^(3+),Eu^(3+)phosphors were prepared via a microwave hydrothermal method by using trisodium citrate dehydrate as surfactant.The phase structure,morphology and photoluminescence properties were measured by powder X-ray diffraction,scanning electron microscope and fluorescence spectrometer,respectively.The results show that uniform spherical microcrystals with diameters in the range of 2–4μm are obtained.And the phase and morphology of samples are not significantly changed by doping rare earth(RE^(3+))ions.Under the excitation wavelength of 356 and 365 nm,the samples BaWO 4:0.03Dy^(3+),yTm^(3+)can emit cold white light.In order to lower the correlated color temperature(CCT)to get a warm white light,the Eu^(3+)ions were doped into BaWO 4:0.03Dy^(3+),0.01Tm^(3+).Especially,under the excitation of 365 nm,BaWO 4:0.03Dy^(3+),0.01Tm^(3+),0.03Eu^(3+)phosphor shew a bright warm white light with color coordi-nate of(0.4013,0.3629)and CCT of 3288 K.Moreover,in the BaWO 4:Dy^(3+),Tm^(3+),Eu^(3+)phosphors,the energy transfer mechanism among Dy^(3+),Tm^(3+)and Eu^(3+)ions have been discussed and the change of electron structures have been calculated by first-principles calculations.The results shew that the uniform single-phase spherical BaWO 4:Dy^(3+),Tm^(3+),Eu^(3+)phosphors could be favorable candidates in warm white LEDs.展开更多
Revealing the epitaxial growth mechanism and the interfacial coupling effect between oxide films will help to build a“structure-property”bridge for the design of microelectronic devices.Here,the epitaxial growth mec...Revealing the epitaxial growth mechanism and the interfacial coupling effect between oxide films will help to build a“structure-property”bridge for the design of microelectronic devices.Here,the epitaxial growth mechanism and the interfacial coupling in Bi_(0.5)Na_(0.5)TiO_(3)/SrTiO_(3)(BNT/STO)heterointerfaces are investigated by the aberration-corrected scanning transmission electron microscopy,which is synthesized by a hydrothermal method.The results illustrate that 4 mol/L NaOH leads to not only the epitaxial growth of the BNT film but also the mutual diffusion of elements.The uneven distribution of local elements in BNT films is observed and confirmed to impact the cation displacements of B-site and lattice distortion.However,the overall trend of B-site cation displacement at the BNT/STO heterointerfaces is dominated by the interfacial strain.Additionally,the oxygen octahedral tilt exhibits continuous tilt patterns of a^(0)a^(0)a^(0)-a−b^(0)c−-a^(0)a^(0)c−-a^(0)b−c−-a−b−c−from the substrate to BNT film due to the constraint of the substrate and presents a strong correlation with cation displacement.These results are helpful to understand the underlying atomic structures and physical properties of BNT epitaxial thin films.展开更多
Fluorinated porous organic networks(F-PONs)have demonstrated unique properties and applications,but approaches capable of affording F-PONs with high fluorine content and robust nanoporous architecture under metal-free...Fluorinated porous organic networks(F-PONs)have demonstrated unique properties and applications,but approaches capable of affording F-PONs with high fluorine content and robust nanoporous architecture under metal-free and easy handling conditions are still rarely reported.Herein,using polydivinylbenzene(PDVB)as an easily available precursor,a novel and straightforward approach was developed to afford F-PONs via a dehydrative Friedel-Crafts reaction using perfluorinated benzylic alcohols as the cross-linking agent promoted by Bronsted acid(trifluoromethanesulfonic acid).The afforded material(F-PDVB)featured high fluorine content(22 at.%),large surface area(771 m^(2)·g^(-1)),and good chemical/thermal stability,rendering them as promising candidates for the adsorption of CO_(2),hydrocarbons,fluorocarbons,and chlorofluorocarbons,with weight capacities up to 520 wt.%being achieved.This simple methodology can be extended to fabricate fluorinated hyper-crosslinked polymers(F-HCPs)from rigid aromatic monomers.The progress made in this work will open new opportunities to further expand the involvement of fluorinated materials in large scale applications.展开更多
基金This work was supported by Priority Academic Program Development(PAPD)of Jiangsu Higher Education Institutions.
文摘A series of uniform single-phase spherical BaWO 4:Dy^(3+),Tm^(3+),Eu^(3+)phosphors were prepared via a microwave hydrothermal method by using trisodium citrate dehydrate as surfactant.The phase structure,morphology and photoluminescence properties were measured by powder X-ray diffraction,scanning electron microscope and fluorescence spectrometer,respectively.The results show that uniform spherical microcrystals with diameters in the range of 2–4μm are obtained.And the phase and morphology of samples are not significantly changed by doping rare earth(RE^(3+))ions.Under the excitation wavelength of 356 and 365 nm,the samples BaWO 4:0.03Dy^(3+),yTm^(3+)can emit cold white light.In order to lower the correlated color temperature(CCT)to get a warm white light,the Eu^(3+)ions were doped into BaWO 4:0.03Dy^(3+),0.01Tm^(3+).Especially,under the excitation of 365 nm,BaWO 4:0.03Dy^(3+),0.01Tm^(3+),0.03Eu^(3+)phosphor shew a bright warm white light with color coordi-nate of(0.4013,0.3629)and CCT of 3288 K.Moreover,in the BaWO 4:Dy^(3+),Tm^(3+),Eu^(3+)phosphors,the energy transfer mechanism among Dy^(3+),Tm^(3+)and Eu^(3+)ions have been discussed and the change of electron structures have been calculated by first-principles calculations.The results shew that the uniform single-phase spherical BaWO 4:Dy^(3+),Tm^(3+),Eu^(3+)phosphors could be favorable candidates in warm white LEDs.
基金supported by the National Natural Science Foundation of China(NSFC)under grant No.51902155the Priority Academic Program Development(PAPD)of Jiangsu Higher Education Institutions.
文摘Revealing the epitaxial growth mechanism and the interfacial coupling effect between oxide films will help to build a“structure-property”bridge for the design of microelectronic devices.Here,the epitaxial growth mechanism and the interfacial coupling in Bi_(0.5)Na_(0.5)TiO_(3)/SrTiO_(3)(BNT/STO)heterointerfaces are investigated by the aberration-corrected scanning transmission electron microscopy,which is synthesized by a hydrothermal method.The results illustrate that 4 mol/L NaOH leads to not only the epitaxial growth of the BNT film but also the mutual diffusion of elements.The uneven distribution of local elements in BNT films is observed and confirmed to impact the cation displacements of B-site and lattice distortion.However,the overall trend of B-site cation displacement at the BNT/STO heterointerfaces is dominated by the interfacial strain.Additionally,the oxygen octahedral tilt exhibits continuous tilt patterns of a^(0)a^(0)a^(0)-a−b^(0)c−-a^(0)a^(0)c−-a^(0)b−c−-a−b−c−from the substrate to BNT film due to the constraint of the substrate and presents a strong correlation with cation displacement.These results are helpful to understand the underlying atomic structures and physical properties of BNT epitaxial thin films.
基金supported financially by the Division of Chemical Sciences,Geosciences,and Biosciences,Office of Basic Energy Sciences,US Department of Energy.
文摘Fluorinated porous organic networks(F-PONs)have demonstrated unique properties and applications,but approaches capable of affording F-PONs with high fluorine content and robust nanoporous architecture under metal-free and easy handling conditions are still rarely reported.Herein,using polydivinylbenzene(PDVB)as an easily available precursor,a novel and straightforward approach was developed to afford F-PONs via a dehydrative Friedel-Crafts reaction using perfluorinated benzylic alcohols as the cross-linking agent promoted by Bronsted acid(trifluoromethanesulfonic acid).The afforded material(F-PDVB)featured high fluorine content(22 at.%),large surface area(771 m^(2)·g^(-1)),and good chemical/thermal stability,rendering them as promising candidates for the adsorption of CO_(2),hydrocarbons,fluorocarbons,and chlorofluorocarbons,with weight capacities up to 520 wt.%being achieved.This simple methodology can be extended to fabricate fluorinated hyper-crosslinked polymers(F-HCPs)from rigid aromatic monomers.The progress made in this work will open new opportunities to further expand the involvement of fluorinated materials in large scale applications.
