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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]

White light phosphors have many potential applications such as solid-state lighting, full color displays, light source for plant growth, and crop improvement. However, most of these phosphors are rare-earth-based materials which are costly and would be facing the challenge of resource issue due to the extremely low abundance of these elements on earth. A new white color composite consisted of a graphitic-phase nitrogen carbon (g-C3N4) treated with nitric acid and copper-cysteamine Cu3Cl(SR)2 is reported herein. Under a single wavelength excitation at 365 nm, these two materials show a strong blue and red luminescence, respectively. It is interesting to find that the white light emission with a quantum yield of 20% can be obtained by mixing these two self-activated luminescent materials at the weight ratio of 1:1.67. Using a 365 nm near-ultraviolet chip for excitation, the composite produces a white light-emitting diode that exhibits an excellent color rendering index of 94.3. These white-emitting materials are environment friendly, easy to synthesize, and cost-effective. More importantly, this will potentially eliminate the challenge of rare earth resources. Furthermore, a single chip is used for excitation instead of a multichip, which can greatly reduce the cost of the devices. [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]

Dy-Bi co-doped yttrium tungstate crystal materials were synthesized by high temperature solid-state method. To reveal the photoluminescence features and properties of the samples, some measurements have been taken. It turned out that different Bi concentrations play obvious influence in emission performance, and show visible light emission under ultraviolet light excitation. Besides, the effect of temperature on phase structure of samples has also been studied here. Superhigh X-ray luminescence of the phosphors exhibited the promising application in the field of high energy detection. The X-ray irradiation crystal resistance stability of the phosphors has also been investigated through the subsequent testing of XRD and spectra. [ABSTRACT FROM AUTHOR]

J. Zhang, W. Chen, and co‐workers report non‐rare‐earth‐based white light phosphors composed of graphitic nitrogen carbon and copper‐cysteamine on page 6833. These composites exhibit a strong luminescence in the blue and red under ultraviolet single excitation, and are environmentally friendly, easy to synthesize, cost‐effective, and free of rare‐earth elements. These new white light phosphors have a good potential in solid lighting, displays, and crop improvement. [ABSTRACT FROM AUTHOR]

Dual-functional ZnWO4:Dy3+, Bi3+ were synthesized via high-temperature solid-state reaction method. The as-prepared samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), photoluminescence spectra and photocatalytic properties. The ZnWO4:Dy3+, Bi3+ phosphor shows photoluminescence with a broad band and the feature Dy3+ emission, and a high photocatalytic activity in degradation of Rhodamine B (RhB) under simulated UV irradiation. The result shows that doping Bi3+ in ZnWO4:Dy3+ can enhance light harvest capability to generate more electron-hole pairs, and acted as a trap center by decreasing the recombination of photogenerated electrons and holes. All of the results obtained by the work suggest that ZnWO4:Dy3+, Bi3+ phosphors are promising materials for the photocatalytic decomposition of pollutants. [ABSTRACT FROM AUTHOR]