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Abstract: SrAl2O4:Eu phosphors with various doping concentrations were synthesized via a urea assisted solution-combustion method in a reducing atmosphere without any post-annealing process. The phosphors were characterized by X-ray powder diffraction (XRD), field emission scanning electron microscopy (SEM), photoluminescence (PL), X-ray excited luminescence (XEL), and X-ray photoelectron spectroscopy (XPS). The XRD results show that the samples exhibit a monoclinic phase in crystal structure. The PL measurements show that the intensity of luminescence emission from divalent Eu2+ ions is increased with increasing europium concentration up to a maximum of 2.5mol%, then decreases at higher concentration due to the concentration quenching effect. The emission from trivalent Eu3+ ions occurs when the doping concentration is higher than 12.5mol%. The XPS measurements also confirm the trends of Eu2+ and Eu3+ with changes in concentration. The results indicate that the luminescence color components of the phosphors can be adjusted by the doping concentration; this is a very important result for practical applications. [Copyright &y& Elsevier]

For the first time, X-ray excited luminescence of Sr 2 MgSi 2 O 7 :Eu 2+ , Dy 3+ , an efficient persistent phosphor with good potential for lighting, biological imaging and photodynamic activation, is reported in this paper. A modified Sol-Gel method is used to synthesize Sr 2 MgSi 2 O 7 :Eu 2+ , Dy 3+ phosphors and their luminescence properties are highly associated with the synthesis conditions. The dependences of the X-ray excited optical luminescence and persistent luminescence of Sr 2 MgSi 2 O 7 :Eu 2+ , Dy 3+ on the reaction pH, temperature, ratio of Eu/Dy, and the calcination duration time are investigated and the association of the luminescence behaviors with the synthesis conditions is explored as a good strategy to optimize the phosphors for practical applications. [ABSTRACT FROM AUTHOR]

Abstract Zn 1-x WO 4 :xLi+ (x = 0, 0.02, 0.05, 0.1) phosphors were synthesized by high-temperature solid-state method. The structural and luminescence properties of the samples were investigated through X-ray diffraction (XRD), scanning electron microscopy (SEM), Microconfocal Raman spectrometer(MR), Diffuse reflectance spectra (DRS) and Photoluminescence spectra. The Li-doped ZnWO 4 phosphors show photoluminescence with a broad band. Compared with the pure ZnWO 4 , the band gap of lithium doped samples shows a red shift measured by Diffuse reflectance spectra (DRS), which could be attributed to the doping effects. Moreover, photocatalytic activity test shows that the Li-doped ZnWO 4 phosphors exhibit higher catalytic activities than the pure ZnWO 4 for the degradation of Rhodamine B by the UV irradiation. The result shows that the Li-doped phosphors can enhance light harvest capability to generate more electron-hole pairs, and act as a trap center by decreasing the recombination of photogenerated electrons and holes. [ABSTRACT FROM AUTHOR]

Abstract Ti4+-doped ZnWO 4 phosphors were synthesized by a facile solid state reaction route. The structural and morphological features of the as-synthesized Ti4+-doped ZnWO 4 photocatalysts were intensively characterized by XRD(X-ray diffraction), XPS(X-ray photoelectron spectroscopy), UV–vis DRS(Ultraviolet-visible diffuse reflectance spectrum), PL(photoluminescence spectroscopy). The photocatalytic reaction tests have been decomposed by the solution of rhodamine B(RhB). The results showed that the Ti4+ -doped ZnWO 4 phosphors had a high photocatalytic activity, and RhB degradation rate of 97% within 120 min was achieved for the 0.01Ti4+-doped sample. The enhancement of photocatalytic performance for Ti4+-doped ZnWO 4 samples can be ascribed to reduce the recombination rate of photogenerated electron-hole pairs with the formation of new defects by Ti4+ doping. This study suggests that Ti4+-doped ZnWO 4 photocatalysts are promising for photocatalytic decomposition of organic contaminants. [ABSTRACT FROM AUTHOR]