Qinghong Fang

Uniform Lu2O3 hollow microspheres: template-directed synthesis and bright white up-conversion luminescence properties

Well-dispersed, uniform Lu2O3 hollow microspheres have been successfully fabricated via a urea-based precipitation method in the presence of colloidal PS microspheres as templates, followed by subsequent heat treatment. The structure, morphology, formation process, and fluorescent properties are well investigated using various techniques. The results indicate that the hollow microspheres can be well indexed to the cubic Lu2O3 phase. The hollow Lu2O3 microspheres with a uniform diameter of about 2.2 μm maintain the spherical morphology and good dispersion of the PS spheres template. The shell of the hollow microspheres consists of numerous nanocrystals with the thickness of approximately 20 nm. Moreover, the possible formation mechanism of evolution from the PS spheres to the amorphous precursor and to the final hollow Lu2O3 microspheres has also been proposed. Under 980 nm laser diode excitation, Lu2O3:Yb3+/Tm3+, Lu2O3:Er3+ and Lu2O3:Yb3+/Er3+ products are mainly dominated by blue, green and red light emissions, respectively. The ratio of the intensity of green luminescence to that of red luminescence decreases with an increase of the concentration of Yb3+ in Lu2O3:Er3+ samples. Furthermore, the UC white light was successfully obtained in the Lu2O3:Yb3+/Er3+/Tm3+ system by adjusting the relative doping concentration of Yb3+, Er3+ and Tm3+. The obtained UC white light has CIE-x = 0.3478 and CIE-y = 0.3143, which are very close to the standard equal energy white light illuminate (x = 0.33, y = 0.33). Because of abundant luminescent colors from RGB to white in Lu2O3:Yb3+/Er3+/Tm3+ samples under 980 nm laser diode (LD) excitation, they can potentially be used as fluorophores in the fields of color displays, backlights, UC lasers, photonics, and biomedicine.

Preparation and characterizations of eucommia ulmoides gum/polypropylene blend

AbstractPolypropylene (PP) blended with eucommia ulnmoides gum (EUG) has been investigated in this work. The mechanical properties, processing properties, crystallinity and microstructure of different blends were researched to find the best mixed ratio of EUG in the blend. The results showed that the impact strength of PP blended with 25xa0% mass fraction of EUG was improved as much as twice and the properties of material were transferred from brittleness to ductility. The survey of DSC indicated that degree of crystallinity (XC) of the blend was first promoted and later inhibited with the mass fraction of EUG increasing, when the weight percent ratio of EUG was 10xa0%, the value of XC got to the maximum of 30.35xa0%. Polarizing microscopes exhibited that the addition of EUG could promote the spherulite refinement and increase significantly amorphous areas of PP. Morphology of fracture surfaces observed by SEM demonstrated that the brittle fracture of pure PP material transformed to the ductile fracture with increasing EUG and then the toughening mechanisms were discussed.

Facile Synthesis and Down-Conversion Emission of RE3+-Doped Lutetium Oxide Nanoparticles

Lu2O3:RE3+ (RE3+ = Eu3+, Tb3+, Ho3+) nanoparticles have been successfully synthesized by a facile homogeneous precipitation method with subsequent sintering process. The crystal structure, morphology and luminescence properties of the as-prepared samples have been characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA), photoluminescence (PL) and cathodoluminescence (CL) spectra. Upon ultraviolet (UV) and low-voltage electron beam excitation, Lu2O3:RE3+ (RE3+ = Eu3+, Tb3+, Ho3+) nanoparticles show strong red (Eu3+,5D0 → 7F2), green (Tb3+,5D4 → 7F5), and green (Ho3+,5S2 → 5I8) emissions. They exhibit a good advantage of multicolor emissions in the visible region, and endow these kinds of materials with potential application in many fields, such as light display systems, optoelectronic devices and biological imaging.

The effect of zeolite particle modified by PEG on rubber composite properties

Abstract The purpose of this paper was to investigate the surface modification of zeolite with polyethylene glycol (PEG) and the modified zeolite as a reinforcing filler partly replacing carbon black (CB) into rubber to prepare the rubber composites. The surface characteristics of zeolite modified by PEG and the unmodified zeolite were characterized by infrared (IR) spectroscopy and scanning electron microscopy (SEM). Moreover, the evaluations of the zeolite/rubber composite were carried out on characteristics such as tensile property, abrasion loss, and hysteresis heat generation with different amounts of zeolite and PEG. The results showed that the tensile strength and elongation at break of the composites were improved, and the abrasion and lag heat generation were reduced when 5–8 phr zeolite modified by 3 wt% PEG was filled into rubber. These results indicated that the modified zeolite has a good compatibility and dispersion in rubber.

Large-scale synthesis of Lu{sub 2}O{sub 3}:Ln{sup 3+} (Ln{sup 3+} = Eu{sup 3+}, Tb{sup 3+}, Yb{sup 3+}/Er{sup 3+}, Yb{sup 3+}/Tm{sup 3+}, and Yb{sup 3+}/Ho{sup 3+}) microspheres and their photoluminescence properties

Graphical abstract: In this work, multicolor and monodisperse Lu{sub 2}O{sub 3}:Ln{sup 3+} (Ln{sup 3+} = Eu{sup 3+}, Tb{sup 3+}, Yb{sup 3+}/Er{sup 3+}, Yb{sup 3+}/Tm{sup 3+}, and Yb{sup 3+}/Ho{sup 3+}) microspheres were prepared by a homogeneous precipitation method followed by a subsequent calcination process. Display Omitted Highlights: ► Lu{sub 2}O{sub 3}:Ln{sup 3+} microspheres were prepared by a precipitation followed by a calcination process. ► Lu{sub 2}O{sub 3}:Eu{sup 3+}/Tb{sup 3+} samples exhibit respective red or green emissions. ► Lu{sub 2}O{sub 3}:Yb{sup 3+}/Er{sup 3+}/Tm{sup 3+}/Ho{sup 3+} exhibit emissions of green, blue, yellow-green, respectively. ► These finding may find potential applications in bioanalysis and field emission displays. -- Abstract: In this work, multicolor and monodisperse Lu{sub 2}O{sub 3}:Ln{sup 3+} (Ln{sup 3+} = Eu{sup 3+}, Tb{sup 3+}, Yb{sup 3+}/Er{sup 3+}, Yb{sup 3+}/Tm{sup 3+}, and Yb{sup 3+}/Ho{sup 3+}) microspheres were prepared by a homogeneous precipitation method followed by a subsequent calcination process. X-ray diffraction (XRD), Fourier transformed infrared (FT-IR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), photoluminescence (PL) spectra, and cathodoluminescence (CL) spectra were employed to characterize the samples. Upon ultraviolet and low-voltage electron beams excitation, Lu{sub 2}O{sub 3}:Ln{sup 3+} (Ln{sup 3+} = Eu{sup 3+} and Tb{sup 3+}) samples exhibit respective brightmorexa0» red (Eu{sup 3+}, {sup 5}D{sub 0} → {sup 7}F{sub 2}) and green (Tb{sup 3+}, {sup 5}D{sub 4} → {sup 7}F{sub 5}) down-conversion (DC) emissions. Under 980 nm NIR irradiation, Lu{sub 2}O{sub 3}:Ln{sup 3+} (Ln{sup 3+} = Yb{sup 3+}/Er{sup 3+}, Yb{sup 3+}/Tm{sup 3+}, and Yb{sup 3+}/Ho{sup 3+}) exhibit characteristic up-conversion (UC) emissions of green (Er{sup 3+}, {sup 4}S{sub 3/2}, {sup 2}H{sub 11/2} → {sup 4}I{sub 15/2}), blue (Tm{sup 3+}, {sup 1}G{sub 4} → {sup 3}H{sub 6}) and yellow-green (Ho{sup 3+}, {sup 5}F{sub 4}, {sup 5}S{sub 2} → {sup 5}I{sub 8}), respectively. These finding may find potential applications in bioanalysis, optoelectronic and nanoscale devices, field emission displays, and so on.«xa0lessAbstract In this work, multicolor and monodisperse Lu2O3:Ln3+ (Ln3+xa0=xa0Eu3+, Tb3+, Yb3+/Er3+, Yb3+/Tm3+, and Yb3+/Ho3+) microspheres were prepared by a homogeneous precipitation method followed by a subsequent calcination process. X-ray diffraction (XRD), Fourier transformed infrared (FT-IR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), photoluminescence (PL) spectra, and cathodoluminescence (CL) spectra were employed to characterize the samples. Upon ultraviolet and low-voltage electron beams excitation, Lu2O3:Ln3+ (Ln3+xa0=xa0Eu3+ and Tb3+) samples exhibit respective bright red (Eu3+, 5D0xa0→xa07F2) and green (Tb3+, 5D4xa0→xa07F5) down-conversion (DC) emissions. Under 980xa0nm NIR irradiation, Lu2O3:Ln3+ (Ln3+xa0=xa0Yb3+/Er3+, Yb3+/Tm3+, and Yb3+/Ho3+) exhibit characteristic up-conversion (UC) emissions of green (Er3+, 4S3/2, 2H11/2xa0→xa04I15/2), blue (Tm3+, 1G4xa0→xa03H6) and yellow-green (Ho3+, 5F4, 5S2xa0→xa05I8), respectively. These finding may find potential applications in bioanalysis, optoelectronic and nanoscale devices, field emission displays, and so on.