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Rare earth-doped phosphor materials have always remained in focus for excellent luminescence properties. Herein we have synthesized Yb3+ and Er3+-doped BaWO4 nanophosphor via facile hydrothermal method with red and green region emissions by 980 nm excitation. Red and green region emissions were observed due to 4F9/2 → 4I15/2 and 2H11/2/4S3/2 → 4I15/2 transitions, respectively, of Er3+, where Yb3+ acts as a sensitizer. The sample characterization was done using X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Transmission Electron Microscopy (TEM), and X-ray Photoelectron Spectroscopy (XPS) techniques. The consequences of different concentrations of activator ion (Er3+) in BaWO4: Yb3+, Er3+ were studied from luminescence perspective in detail. The intensity of overall emission varied with altering the power of excitation that influences the photon transfer pathways. It was found that two-photon processes control both red and green emissions in the upconversion process. Decay behavior for both the emission was investigated. Thus, the tunable photoluminescence property suggests its potential in optoelectronic applications. [ABSTRACT FROM AUTHOR]

In the recent days, rare-earth doped phosphors have attracted an immense attraction in luminescence field for various solid-state lighting and electronic display device applications. However, need of efficient red phosphor is a prevalent challenge in this field. Herein, we report a bright red light emitting Na+ co-doped SrAl2O4:Eu3+ phosphor which is synthesized by modified sol–gel technique. These nanophosphors show excellent red emission due to characteristic 5D0 → 7Fj (j = 1, 2, 3, 4) transitions of the doped Eu3+ ions excited by 394 nm. Photoluminescence studies of both Eu3+ doped SrAl2O4 and Na+ co-doped SrAl2O4:Eu3+ has shown more than fourfold increase in the intensity for optimum Na+ addition. The improved decay time obtained from decay measurement has revealed that the co-doped Na+ has successfully reduced the nonradiative transitions. Thus, addition of monovalent Na+ to Eu3+ doped SrAl2O4 was found to be effective to address the charge imbalance problem along with significant enhancement in luminescence intensity and decay time. The results suggest that this nanophosphor could be a major candidate in the rapidly increasing field of solid-state lighting applications. [ABSTRACT FROM AUTHOR]

Upconverting nanophosphors are a special class of luminescent nanomaterials where lanthanide dopant assisted anti-stokes emission is exploited to achieve a wide range of applications. Herein we report Yb3+/Ho3+ co-doped BaWO 4 nanophosphor with a significant thermal and chemical stability synthesized by a low-temperature hydrothermal process with red (655 nm) and green (538 nm) double color upconversion (UC) under 980 nm near-infrared (NIR) excitation, resulting in yellow emission. The synthesized samples were characterized by X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Vis–NIR Spectroscopy and Transmission Electron Microscopy (TEM) techniques. The dependence of emission behavior on various concentrations of activator ion (Ho3+) in BaWO 4 : Yb3+:Ho3+ phosphors were studied in detail. Temperature dependent emission spectra revealed that the phosphor possesses stable emission up to 200 °C and luminescence intensity drop of only 11.5% of the initial luminescence intensity was observed at 150 °C. Therefore, the luminescence behavior and the thermal stability of the phosphor suggest an effective pathway in the optoelectronic applications. Image 1 [ABSTRACT FROM AUTHOR]

Generation of white light requires a proficient strategy for appropriate mixing of red, green and blue emissions in appropriate proportion through optimization of material composition. However, it is quite challenging to develop a single host material showing emission in full visible region, which can be excited by a single excitation source. Herein, a series of Yb3+-sensitized Ho3+/Tm3+ co-doped BaWO4 nanophosphors synthesized by hydrothermal method is reported. The effect of different concentration of sensitizer ion (Yb3+) on the luminescence properties of BaWO4:Yb3+/Ho3+/Tm3+ crystal is investigated in detail to obtain white light. The phosphors exhibited red, green and blue luminescence centered at 651 nm, 539 nm and 482 nm respectively under a 980 nm excitation. The obtained novel nanophosphor could be a major potential candidate for nanobiotechnology and optoelectronics device applications. [ABSTRACT FROM AUTHOR]