Jian-Xin Meng

Ba1−xSrxMgSiO4:Eu2+,Mn2+: A novel tunable single-matrix tricolor phosphor for W-LED

Abstract The Ba1−xSrxMgSiO4:Eu2+,Mn2+ phosphors were prepared by solid-state reaction. Their photoluminescence properties were investigated with fluorescence spectrum and CIE chromaticity. The emission color of Eu2+ in Ba0.98−xSrxMgSiO4:0.02Eu2+ could be tuned from green to blue by adjusting the content of Sr2+. The blue emission of Eu2+ overlapped well with the excitation spectra of Mn2+, leading to an efficient energy transfer from Eu2+ to Mn2+ in Ba0.98−xSrxMg1−ySiO4:0.02Eu2+,yMn2+. Ba0.93Sr0.03Mg1−ySiO4:0.02Eu2+,yMn2+ could emit three efficient broad bands at 440, 530 and 640 nm. The emission color of Ba0.93Sr0.03Mg1−ySiO4:0.02Eu2+,yMn2+ could be tuned from greenish blue to yellowish white by increasing the content of Mn2+ from 0 to 0.1. By changing the content of Sr2+/Mn2+, white-light with different hues could be conveniently obtained in the Ba1−xSrxMgSiO4:Eu2+,Mn2+ phosphors. The results showed that Ba1−xSrxMgSiO4:Eu2+,Mn2+ is a promising single-phased tricolor phosphor in the fabrication of W-LED.

Fluorimetry determination of trace Ce3+ with EDTP

The use of ethylenediaminetetrakis(methylphosphonic) acid (EDTP) in the fluorimetry determination of trace amounts of Ce3+ ions is described. The fluorescence intensity of Ce3+ was greatly enhanced when an 1:1 complex with EDTP in solution of pH 7-8 formed. The apparent excitation and emission wavelength used were 313 and 397 nm, respectively. The fluorescence intensity varied linearly with the concentration of Ce3+ in the range of 1 x 10(-8) -1 x 10(-4) mol l(-1). The quenching effects of coexist ions (other rare earth ions, Fe3+ and some inorganic anions) were studied. This technique has unique advantage in eliminating disturb of coexist.

一步低温法制备可见光响应的棕色纳米TiO 2 及其光催化性能

ABSTRACT We report a facile and modified sol-gel approach to synthesize brown TiO 2 nanoparticles at low temperature (100–600 °C). The TiO 2 nanoparticles dried at 180 °C (TiO 2 -180°C) possessed a small particle size (5.0 nm), large specific surface area (213.45 m 2 /g), and efficient response to broadband light over the entire ultraviolet-visible spectrum with a narrow band gap of 1.84 eV. In addition, TiO 2 -180°C exhibited the optimal reaction rate constant for the degradation of methylene blue (0.08287 mg/(L·min)), which is six times higher than that of the mixed rutile/anatase phase TiO 2 photocatalytic standard P25 (0.01342 mg/(L·min)). Furthermore, cycling photodegradation experiments confirmed the stability and reusability of this catalyst. The unique physicochemical properties resulting from the low-temperature preparation of TiO 2 -180°C, including its broadband visible absorption associated with a high concentration of oxygen vacancies, large surface area, and enriched surface –OH/H 2 O may be responsible for this excellent photocatalytic performance. The use of as-prepared TiO 2 -180°C for practical applications is expected after further optimization.

Synthesis and luminescence of novel near‐infrared emitting BaZrSi3O9:Cr3+ phosphors

The BaZrSi3 O9 :Cr3+ phosphors were prepared by a high temperature solid state method. Their structures were confirmed with XRD and their luminescence properties were investigated. Under excitation at 455 nm, BaZrSi3 O9 :Cr3+ phosphors exhibited a broad near infrared emission band peaked at 800 nm, which was assigned to the 4 T2 →4 A2 transition of Cr3+ . The near infrared emission intensity reached a maximum at Cr3+ concentration of 0.7%. There was a concentration quenching phenomenon of Cr3+ in BaZrSi3 O9 matrix and the corresponding concentration quenching mechanism was investigated. With efficient near infrared emission in the range of 700-1000 nm, BaZrSi3 O9 :Cr3+ phosphors may find applications in solar energy conversion.