Wenxin Wang

Northeast Institute of Geography and Agroecology, Beijing, Beijing Shi, China

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Publications (29)97.7 Total impact

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    ABSTRACT: Porous silica microspheres were fabricated by a facile surface-protected etching strategy. Polyvinylpyrrolidone (PVP) was used as a protecting polymer absorbed on the surface of silica microspheres and NaOH was employed as an etching agent. Owing to the protective action of PVP and inhomogeneous etching, mesopores were created in the silica microspheres. Then, based on the Pechini-type sol-gel and impregnating process, YVO(4):Eu(3+) nanocrystals were integrated into the channels to form highly luminescent YVO(4):Eu(3+)@SiO(2) composite microspheres. The biocompatibility tests on L929 fibroblast cells using MTT assay reveal low cytotoxicity of the system. Owing to the large interior space and electrostatic interaction, the porous microspheres show a relatively high loading capacity (438 mg DOX/YVO(4):Eu(3+)@SiO(2) g) and encapsulation efficiency (87.6%) for the anti-cancer drug doxorubicin hydrochloride (DOX). The drug release behavior and cytotoxic effect against human cervical carcinoma cells (HeLa cells) of the DOX-loaded YVO(4):Eu(3+)@SiO(2) carriers were investigated in vitro. It was found that the carriers present a highly pH-dependent drug release behavior due to electrostatic interaction between the silica surface and DOX molecules. The drug release rate became greater at low pH owing to the increased electrostatic repulsion. The DOX-loaded carriers demonstrate a similar or even greater anti-cancer activity with respect to the free DOX against HeLa cells. Furthermore, the PL intensity of the microspheres shows correlation with the cumulative release of DOX. These results suggest that the composite can potentially act as a multifunctional drug carrier system with luminescent tagging and pH-controlled release properties.
    Dalton Transactions 11/2011; 41(5):1481-9. · 3.81 Impact Factor
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    ABSTRACT: The multicolor patterned luminescent films of CaWO(4):Eu(3+) (red), CaWO(4):Tb(3+) (green), and pure CaWO(4) (blue) on quartz substrates were fabricated by the facile and low-cost microcontact printing (μCP) method combining with the Pechini sol-gel route. On the basis of the μCP process, a hydrophobic self-assembled monolayer (SAM) was first created on the hydrophilic surface of quartz substrates by poly(dimethylsiloxane) (PDMS) mold printing, and then, the multicolor patterned luminescent films were selectively deposited on the hydrophilic regions via a spin coating process and heating treatment. The X-ray diffraction, optical microscopy, scanning electron microscopy, and photoluminescence (PL) spectra were used to characterize the structure and fluorescence properties of the corresponding samples. The results demonstrate that the μCP process can be used for patterning the inorganic phosphor materials and have potential for fabricating rare-earth luminescent pixels for the applications of display devices.
    ACS Applied Materials & Interfaces 09/2011; 3(10):3921-8. · 5.90 Impact Factor
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    ABSTRACT: Gd(2)(WO(4))(3) doped with Eu(3+) or Tb(3+) thin phosphor films with dot patterns have been prepared by a combinational method of sol-gel process and microcontact printing. This process utilizes a PDMS elastomeric mold as the stamp to create heterogeneous pattern on quartz substrates firstly and then combined with a Pechini-type sol-gel process to selectively deposit the luminescent phosphors on hydrophilic regions, in which a Gd(2)(WO(4))(3):Ln(3+) (Ln=Eu, Tb) precursor solutions were employed as ink. X-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence (PL) spectra, as well as low voltage cathodoluminescence (CL) spectra were carried out to characterize the obtained samples. Under ultraviolet excitation and low-voltage electron beams excitation, the Gd(2)(WO(4))(3):Eu(3+) samples exhibit a strong red emission arising from Eu(3+)(5)D(0,1,2)-(7)F(1,2) transitions, while the Gd(2)(WO(4))(3):Tb(3+) samples show the green emission coming from the characteristic emission of Tb(3+) corresponding to (5)D(4)-(7)F(6,5,4,3) transitions. The results show that the patterning of rare earth-doped phosphors through combining microcontact printing with a Pechini-type sol-gel route has potential for field emission displays (FEDs) applications.
    Journal of Colloid and Interface Science 09/2011; 365(1):320-5. · 3.55 Impact Factor
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    ABSTRACT: Uniform hollow Lu(2)O(3):Ln (Ln = Eu(3+), Tb(3+)) phosphors have been successfully prepared via a urea-assisted homogeneous precipitation method using carbon spheres as templates, followed by a subsequent calcination process. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transformed infrared (FT-IR), thermogravimetric and differential thermal analysis (TG-DTA), photoluminescence (PL) spectra, cathodoluminescence (CL) spectra, kinetic decays, quantum yields (QY), and UV-visible diffuse reflectance spectra were employed to characterize the samples. The results show that hollow Lu(2)O(3):Ln spheres can be indexed to cubic Gd(2)O(3) phase with high purity. The as-prepared hollow Lu(2)O(3):Ln phosphors are confirmed to be uniform in shape and size with diameter of about 300 nm and shell thickness of approximate 20 nm. The possible formation mechanism of evolution from the carbon spheres to the amorphous precursor and to the final hollow Lu(2)O(3):Ln microspheres has been proposed. Upon ultraviolet (UV) and low-voltage electron beams excitation, the hollow Lu(2)O(3):Ln (Ln = Eu(3+), Tb(3+)) spheres exhibit bright red (Eu(3+), (5)D(0)-(7)F(2)) and green (Tb(3+), (5)D(4)-(7)F(5)) luminescence, which may find potential applications in the fields of color display and biomedicine.
    Inorganic Chemistry 02/2011; 50(6):2182-90. · 4.59 Impact Factor
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    ABSTRACT: One-dimensional Tb(2)(WO(4))(3) and Tb(2)(WO(4))(3):Eu(3+) nanowires have been prepared by a combination method of sol-gel process and electrospinning. X-Ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), photoluminescence (PL), low voltage cathodoluminescence (CL) and time-resolved emission spectra as well as kinetic decays were used to characterize the resulting samples. The as-obtained precursor samples present fiber-like morphology with uniform size, and Tb(2)(WO(4))(3) and Tb(2)(WO(4))(3):Eu(3+) nanowires were formed after annealing. Under ultraviolet excitation and low-voltage electron beams excitation into WO(4)(2-) and the f-f transition of Tb(3+), the Tb(2)(WO(4))(3) samples show the characteristic emission of Tb(3+) corresponding to (5)D(4)-(7)F(6, 5, 4, 3) transitions due to an efficient energy transfer from WO(4)(2-) to Tb(3+), while Tb(2)(WO(4))(3):Eu(3+) samples mainly exhibit the characteristic emission of Eu(3+) corresponding to (5)D(0)-(7)F(0, 1, 2) transitions due to an energy transfer occurs from WO(4)(2-) and Tb(3+) to Eu(3+). The increase of Eu(3+) concentration leads to the increase of the energy transfer efficiency from Tb(3+) to Eu(3+). The PL color of Tb(2)(WO(4))(3):x mol% Eu(3+) phosphors can be tuned from green to red easily by changing the doping concentration (x) of Eu(3+), making the materials have potential applications in fluorescent lamps and color display fields.
    Nanoscale 02/2011; 3(4):1568-74. · 6.73 Impact Factor
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    ABSTRACT: One-dimensional GdVO4:Ln3+ (Ln=Eu, Dy, Sm) nanofibers have been prepared by a combination method of sol–gel process and electrospinning technology. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric and differential thermal analysis (TG-DTA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), photoluminescence (PL), quantum efficiency (QE), and cathodoluminescence (CL) spectra as well as kinetic decays were used to characterize the samples. The XRD, FT-IR, and TG-DTA results show that GdVO4:Ln3+ nanofibers samples crystallize at 700 °C. SEM images indicate that the as prepared precursor fibers are smooth. After being calcined at 700 °C for 4 h, the fibers still maintain their fiberlike morphology with rough surface. TEM image further manifests that the GdVO4:Ln3+ nanofibers consist of nanoparticles. Under ultraviolet excitation and low-voltage electron beam excitation, GdVO4:Ln3+ phosphors showed their strong characteristic emission due to an efficient energy transfer from vanadate groups to dopants. The optimum doping concentration of Ln3+ in the GdVO4 nanofibers also has been investigated.Graphical abstractResearch Highlights►1D and Q-1D GdVO4 fiber-like nanostructures were prepared electrospinning technique. ►Under ultraviolet excitation and electron beam excitation, the Ln3+ ions show their characteristic emissions, respectively. ►The quantum efficiencies are 14 (Eu3+), 6 (Dy3+), and 5 % (Sm3+) in GdVO4, respectively.
    Journal of Solid State Chemistry 01/2011; 184(1):141-148. · 2.04 Impact Factor
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    ABSTRACT: LaPO4:Ln3+ (Ln=Eu, Ce, Tb) nanocrystals were successfully synthesized via a facile solvothermal process in the presence of oleic acid. The as-prepared crystals were well characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectra (XPS), Fourier transform infrared spectroscopy (FT-IR), optical spectra as well as the kinetic decay times, respectively. In the synthesis process, oleic acid as a surfactant has played a crucial role in confining the growth and size of the LaPO4:Ln3+ phosphors. All the samples are well crystallized and assigned to the monoclinic monazite-type structure of the LaPO4 phase. The prepared LaPO4:Ln3+ phosphors present a narrow distribution with an average particle size of about 15nm. Upon excitation by ultraviolet radiation, the LaPO4:Eu3+ phosphors show the characteristic 5D0–7F1–3 emission lines of Eu3+, while the LaPO4:Ce3+,Tb3+ exhibits the characteristic 5D0–7F3–6 emission lines of Tb3+. It is believed that these rare earth ion doped (Eu3+ ion or Ce3+ and Tb3+ ions co-doped) monoclinic monazite-type LaPO4 nanocrystals could find potential application as future advanced optical materials.
    Solid State Ionics 01/2011; 509(6):3096-3102. · 2.05 Impact Factor
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    ABSTRACT: The core-shell structured LaInO3:Ln3+@SiO2 (Ln3+ = Sm3+, Tb3+) phosphors were realized by coating LaInO3:Ln3+ phosphors on the surface of silica microspheres via a modified Pechini sol–gel process. The phase, structure, morphology, and fluorescent properties of the materials were well characterized by means of X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier transform IR spectroscopy (FT-IR), photoluminescence (PL) spectra, cathodoluminescence (CL) spectra, and the kinetic decays, respectively. The results reveal that the obtained core-shell structured phosphors consist of amorphous silica core and crystalline LaInO3:Ln3+ shell, which keep the uniform spherical morphology of pure silica spheres with narrow size distribution. Upon excitation by ultraviolet (UV) irradiation or electron beam, the phosphors show the characteristic emission lines of Sm3+ (4G5/2–6H5/2,7/2,9/2, orange) in LaInO3:Sm3+@SiO2 and characteristic emissions of Tb3+ (5D4–7F6,5,4,3, green) in LaInO3:Tb3+@SiO2, respectively. This kind of phosphors may have potential applications in field emission displays (FEDs) based on their uniform shape, low-cost synthetic route, and diverse luminescent properties.Graphical abstractThe core-shell structured LaInO3:Ln3+@SiO2 phosphors were realized by coating LaInO3:Ln3+ phosphors on the surface of silica microspheres via a modified Pechini sol–gel process.Research highlights▶ A facile and low-cost sol-gel process was used to fabricate fluorescent microspheres. ▶ Uniform core-shell structured phosphors with bright PL emissions were obtained. ▶ The possible formation scheme for the core-shell structured spheres is presented.
    Journal of Alloys and Compounds 01/2011; 509(3):837-844. · 2.73 Impact Factor
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    ABSTRACT: Rare-earth ions (Eu3+, Tb3+, Dy3+) doped SrMoO4 nanoparticles were prepared by solvothermal route using oleic acid as surfactant to control the particle shape and size. X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectra (XPS), photoluminescence spectra (PL) and the kinetic decay times were applied to characterize the obtained samples. The XRD patterns reveal that all the doped samples are assigned to the scheelite-type tetragonal structure of SrMoO4 phase. In addition, the as-synthesized SrMoO4:Ln (Ln=Eu3+, Tb3+, Dy3+) particles are high purity well crystallized and with the average size of 30–50nm. The possible formation process of SrMoO4:Ln (Ln=Eu3+, Tb3+, Dy3+) nanoparticles have been discussed as well. Upon excitation by ultraviolet radiation, the as-synthesized SrMoO4:Ln (Ln=Eu3+, Tb3+, Dy3+) nanoparticles exhibit the characteristic emission lines of corresponding Eu3+, Tb3+, Dy3+, respectively.
    Materials Research Bulletin - MATER RES BULL. 01/2011; 46(3):333-339.
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    ABSTRACT: Eu3+, Dy3+ and Sm3+ doped nano-sized YP0.8V0.2O4 phosphors were synthesized by a simple and facile microwave assisted hydrothermal process. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), photoluminescence (PL) spectra as well as kinetic decay were used to characterize the samples. Under ultraviolet excitation, the YP0.8V0.2O4:Ln3+ showed the VO43− self-emission band at approximately 452nm and the characteristic emission of doped lanthanide ions (Ln3+). The VO43− self-emission band decreases when the concentration of lanthanide ion increases, because lanthanide ions acts as activator and receives an efficient energy transfer from VO43−. Through changing the kinds and concentrations of doped Ln3+, the emission colors of the nanophosphor can be tuned in a wide region on CIE color coordinates, making the material have potential application in biolabels.
    Surface Science - SURFACE SCI. 01/2011; 129(1):418-423.
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    ABSTRACT: LaPO4, LaPO4:Ce3+ and LaPO4:Ce3+, Tb3+ particles with different morphologies and sizes have been successfully synthesized via a simple EDTA assisted hydrothermal method. The effects of the doping components, pH value, and the chelating reagent on the phases, structures and morphologies were well investigated by means of X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Photoluminescent (PL) spectra and kinetic decays were used to characterize the fluorescent properties of the samples. The results reveal that all the samples are of high purity and assigned to the single-crystalline monoclinic structure of LaPO4 phase. The aspects ratio of the nanostructures synthesized in acid synthetic condition is larger than those obtained in alkaline solution. Additionally, the Ce3+ or/and Tb3+ doped LaPO4 particles show less smoother surface compared with pure LaPO4. Furthermore, the tendency for anisotropic growth under hydrothermal conditions can be simply enhanced by selecting the chelating ligands (EDTA). The possible growth mechanism of the LaPO4:Ln3+ (Ln = Ce3+, Tb3+) nanostructures has been proposed as well. Upon ultraviolet excitation, LaPO4:Ce3+ and LaPO4:Ce3+, Tb3+ phosphors show the characteristic 5d–4f emissions of Ce3+ and 5D4–7Fj (j = 6–3) emission lines of Tb3+, respectively.Graphical abstractLaPO4, LaPO4:Ce3+ and LaPO4:Ce3+, Tb3+ particles with various morphologies and sizes have been successfully prepared via a facile EDTA assisted hydrothermal method.
    ChemInform 11/2010; 12(9):1652-1660.
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    ABSTRACT: Ordered arrays of luminescent YVO4:Eu3+ films with square (side length 19.17 ± 2.05 μm) and dot (diameter 11.20 ± 1.82 μm) patterns were fabricated by two kinds of soft lithography processes, namely, microtransfer molding (μTM) and microcontact printing (μCP), respectively. Both soft-lithography processes utilize a PDMS elastomeric mold as the stamp combined with a Pechini-type sol-gel process to produce luminescent patterns on quartz plates, in which a YVO4:Eu3+ precursor solution was employed as ink. The ordered luminescent YVO4:Eu3+ patterns are revealed by optical micro­scopy and their microstructure, consisting of nanometer-scale particles, is unveiled by scanning electronic microscopy (SEM) observations. Additionally, photoluminescence (PL) and cathodoluminescence (CL) were carried out to characterize the patterned YVO4:Eu3+ samples. A strong red emission as a result of 5D0–7F2 transition of Eu3+ was observed under UV-light or electron-beam excitation, which implies that combining soft lithography with a Pechini-type sol-gel route has potential for fabricating rare-earth luminescent pixels for next-generation field-emission display devices.
    Advanced Functional Materials 11/2010; 21(3):456 - 463. · 10.44 Impact Factor
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    ABSTRACT: Luminescent and porous silica fibers have been successfully prepared by using the electrospinning process. The obtained multifunctional silica fibers, which possess a porous structure and display blue luminescence, can serve as a drug delivery host carrier, using ibuprofen (IBU) as a model drug, allowing the investigation of storage/release properties. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FT-IR), N(2) adsorption/desorption, photoluminescence (PL) spectra, and kinetic decay were used to characterize the structural, morphological, and optical properties of the as-obtained samples. The results reveal that the multifunctional silica materials exhibit an irregular porous structure, and display a fiberlike morphology with dimensions of several hundred nanometers in width and several millimeters in length. The obtained silica fibers exhibit an intense broad bluish emission, which might be attributed to impurities and/or defects in the silica fibers. The IBU-loaded silica fiber system shows blue luminescence under UV irradiation and controlled release behavior for IBU. In addition, the emission intensities of silica fibers in the drug carrier system vary with the released amount of IBU, thus allowing the drug release to be easily tracked and monitored by the change of the luminescence intensity.
    Chemistry 11/2010; 16(48):14513-9. · 5.93 Impact Factor
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    ABSTRACT: Hollow Gd2O3:Ln (Ln = Eu3+, Sm3+) microspheres were successfully fabricated by using carbon spheres as a template and urea as a precipitating agent, which involved the deposition of an inorganic coating on the surface of carbon spheres and subsequent calcination in the air. Various approaches including X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR), thermogravimetric and differential thermal analysis (TG-DTA), photoluminescence spectroscopy as well as kinetic decays were used to characterize the samples. The results indicate that the as-prepared products can be indexed to pure cubic Gd2O3 phase. The samples are composed of uniform hollow Gd2O3:Ln spheres with a mean particle size of about 300 nm. The possible mechanism of evolution from glucose to carbon microspheres and the chemical reaction of each step to form the final hollow spheres are proposed. In particular, the urea-assisted precipitation process was carried out in aqueous solution without any organic solvent, and the hollow spheres formation process was achieved by simple calcination without using any etching agents. The hollow Gd2O3:Ln phosphors exhibit light emission under ultraviolet excitation, which may find promising applications in the fields of field emission displays (FED) and MRI contrast agents.
    CrystEngComm 10/2010; 12(11):3717-3723. · 3.88 Impact Factor
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    ABSTRACT: LaCO(3)OH nano/microcrystals with a variety of morphologies/sizes including nanoflakes, microflowers, nano/microrhombuses, two-double microhexagrams sandwichlike microspindles, and peach-nucleus-shaped microcrystals have been synthesized via a facile homogeneous precipitation route under mild conditions. A series of controlled experiments indicate that the pH values in the initial reaction systems, carbon sources, and simple ions (NH(4)(+) and Na(+)) were responsible for the shape determination of the LaCO(3)OH products. A possible formation mechanism for these products with diverse architectures has been presented. After annealing at suitable temperatures, LaCO(3)OH was easily converted to La(2)O(2)CO(3) and La(2)O(3) with the initial morphologies. A systematic study on the photoluminescence and cathodoluminescence properties of Eu(3+)- or Tb(3+)-doped La(2)O(2)CO(3)/La(2)O(3) samples has been performed in detail. The excitation and site-selective emission spectra were recorded to investigate the microstructure, site symmetry, and difference in the (5)D(0) → (7)F(2) transition of Eu(3+) ions in La(2)O(2)CO(3) and La(2)O(3) host lattices. In addition, the dependence of the luminescent intensity on the morphology for the as-prepared La(2)O(2)CO(3)/La(2)O(3):Ln(3+) (Ln = Eu, Tb) samples has been investigated. The ability of generating diverse morphologies and multiemitting colors for different rare-earth activator ion (Ln = Eu, Tb) doped La(2)O(2)CO(3)/La(2)O(3) nano/microstructures provides a great opportunity for the systematic evaluation of morphology-dependent luminescence properties, as well as the full exploration of their application in many types of color display fields.
    Inorganic Chemistry 10/2010; 49(22):10522-35. · 4.59 Impact Factor
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    ABSTRACT: One-dimensional Lu(2)O(3):Eu(3+) nanofibers have been prepared by a combination method of sol-gel process and electrospinning technology. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric and differential thermal analysis (TG-DTA), scanning electron microscopy (SEM), energy-dispersive X-ray spectrum (EDS), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), photoluminescence (PL), and cathodoluminescence (CL) spectra were used to characterize the samples. The XRD, FT-IR and TG-DTA results show that Lu(2)O(3):Eu(3+) samples crystallize at 900 degrees C. SEM images indicate that as prepared precursor samples and those annealed at 900 degrees C present uniform fiberlike morphology. After being heated at 900 degrees C, the diameters of fibers decrease greatly, ranging from 90 to 180nm. TEM image further manifests that the as-formed Lu(2)O(3):Eu(3+) nanofibers consist of nanoparticles (the crystallite size is about 16.5nm). Under the short wavelength ultraviolet irradiation and the low-voltage electron beam excitation, Lu(2)O(3):Eu(3+) nanofibers all exhibit typical red ((5)D(0)-(7)F(J)) emission. The optimum doping concentration of Eu(3+) in the Lu(2)O(3) nanofibers also has been investigated.
    Journal of Colloid and Interface Science 09/2010; 349(1):166-72. · 3.55 Impact Factor
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    ABSTRACT: One-dimensional Lu2O3:Eu3+ nanofibers have been prepared by a combination method of sol–gel process and electrospinning technology. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric and differential thermal analysis (TG–DTA), scanning electron microscopy (SEM), energy-dispersive X-ray spectrum (EDS), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), photoluminescence (PL), and cathodoluminescence (CL) spectra were used to characterize the samples. The XRD, FT-IR and TG–DTA results show that Lu2O3:Eu3+ samples crystallize at 900 °C. SEM images indicate that as prepared precursor samples and those annealed at 900 °C present uniform fiberlike morphology. After being heated at 900 °C, the diameters of fibers decrease greatly, ranging from 90 to 180 nm. TEM image further manifests that the as-formed Lu2O3:Eu3+ nanofibers consist of nanoparticles (the crystallite size is about 16.5 nm). Under the short wavelength ultraviolet irradiation and the low-voltage electron beam excitation, Lu2O3:Eu3+ nanofibers all exhibit typical red (5D0–7FJ) emission. The optimum doping concentration of Eu3+ in the Lu2O3 nanofibers also has been investigated.
    Journal of Colloid and Interface Science 09/2010; 349(1):166–172. · 3.55 Impact Factor
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    ABSTRACT: One-dimensional LaOCl: Ln3+ (Ln3+ = Eu3+/Sm3+, Tb3+, Tm3+) nanofibers, nanotubes, and quasi-1D microbelts are successfully prepared by a sol–gel/electrospinning process. XRD, FT-IR, SEM, TEM, as well as photoluminescence (PL) and cathodoluminescecne (CL) spectra are used to characterize the resulting samples. Through a heat treatment process at high temperature, the as-prepared samples are well-crystallized with the tetragonal structure of LaOCl. Under ultraviolet radiation and low-voltage electron beam excitation, the LaOCl: Eu3+, LaOCl:Sm3+, LaOCl: Tb3+, and LaOCl: Tm3+ samples give the characteristic transitions of Eu3+ (5D0, 1, 2 → 7F0, 1, 2, 3, 4), Sm3+ (4G5/2 → 6H5/2, 7/2, 9/2), Tb3+ (5D3, 4 → 7F2, 3, 4, 5, 6), and Tm3+ (1D2, 1G4 → 3F4, 3H6), respectively. Moreover, there exists simultaneous luminescence of Tb3+, Tm3+, Eu3+, or Sm3+ individually when codoping them in the single-phase LaOCl host (for example, LaOCl: Tb3+, Eu3+/Sm3+; LaOCl: Tm3+, Eu3+/Sm3+; LaOCl: Tb3+, Tm3+, Eu3+/Sm3+ systems), which is beneficial to tune the emission colors. Under low-voltage electron beam excitation (1–5 kV), a variety of colors can be efficiently adjusted in a wide triangle region enveloped by three CIE chromaticity coordinate points [LaOCl:Eu3+, (x = 0.6039, y = 0.3796); LaOCl: Tb3+, (x = 0.2452, y = 0.5236); LaOCl: Tm3+, (x = 0.1456, y = 0.0702)] for mono- and co-doped LaOCl: Ln3+ (Eu3+, Sm3+, Tb3+, Tm3+) samples, making these materials have potential applications in field-emission display devices.
    Advanced Functional Materials 08/2010; 20(20):3446 - 3456. · 10.44 Impact Factor
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    ABSTRACT: The synthesis (by a facile two-step sol–gel process), characterization, and application in controlled drug release is reported for monodisperse core–shell-structured Fe3O4@nSiO2@mSiO2@NaYF4: Yb3+, Er3+/Tm3+ nanocomposites with mesoporous, up-conversion luminescent, and magnetic properties. The nanocomposites show typical ordered mesoporous characteristics and a monodisperse spherical morphology with narrow size distribution (around 80 nm). In addition, they exhibit high magnetization (38.0 emu g−1, thus it is possible for drug targeting under a foreign magnetic field) and unique up-conversion emission (green for Yb3+/Er3+ and blue for Yb3+/Tm3+) under 980 nm laser excitation even after loading with drug molecules. Drug release tests suggest that the multifunctional nanocomposites have a controlled drug release property. Interestingly, the up-conversion emission intensity of the multifunctional carrier increases with the released amount of model drug, thus allowing the release process to be monitored and tracked by the change of photoluminescence intensity. This composite can act as a multifunctional drug carrier system, which can realize the targeting and monitoring of drugs simultaneously.
    Advanced Functional Materials 03/2010; 20(7):1166 - 1172. · 10.44 Impact Factor
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    ABSTRACT: Rare-earth ions (Eu3+, Dy3+, Sm3+) doped YVO4 microspheres with uniform morphologies were successfully prepared via a simple hydrothermal route using N,N-dimethylformamide (DMF) as the solvent and polyvinylpyrrolidone (PVP) as protective agent. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), photoluminescence (PL) spectra, and the kinetic decays were employed to examine the resulting phase formation, particle morphology and luminescent properties. The XRD results reveal that all the doped samples are of high crystallization which are assigned to the pure tetragonal phase of YVO4. Additionally, the DMF/H2O volume ratio and the concentration of PVP both have obvious effects on the morphologies and sizes of the as-synthesized products. The sample prepared at 180 °C for 24 h with the DMF/H2O volume ratio of 3/1 and 0.4 g/L PVP concentration exhibits uniformly spherical shape with the diameter of 1–2 μm. Upon excitation by ultraviolet radiation or low-voltage electron beams excitation, the YVO4:Ln3+ (Ln = Eu, Dy, and Sm) samples show strong light emissions with different colors from the doped Ln3+ ions. These phosphors exhibit potential applications in the fields of fluorescent lamps and light emitting diodes (LEDs).
    Journal of Colloid and Interface Science 03/2010; 343(1):71–78. · 3.55 Impact Factor

Publication Stats

86 Citations
97.70 Total Impact Points

Institutions

  • 2010–2011
    • Northeast Institute of Geography and Agroecology
      • Key Laboratory of Rare Earth Chemistry and Physics
      Beijing, Beijing Shi, China
    • Chinese Academy of Sciences
      • Key Laboratory of Rare Earth Chemistry and Physics
      Peping, Beijing, China
  • 2008–2011
    • Harbin Engineering University
      • College of Material Science and Chemical Engineering
      Harbin, Heilongjiang Sheng, China