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A series of NaLaMgWO 6 :Dy 3+ phosphors were prepared by a conventional solid-state reaction method at high temperature. The phase structure, morphology, particle size distribution and concentration dependent luminescence properties of the phosphors were investigated for the first time. Upon excitation with UV (290 nm) and n-UV (388 nm), NaLaMgWO 6 :Dy 3+ phosphor exhibited typical Dy 3+ emission corresponding to the 4 F 9/2 → 6 H J ( J = 15/2, 13/2, 11/2) transitions of Dy 3+ , in which the hypersensitive electronic dipole transition 4 F 9/2 → 6 H 13/2 (575 nm) was with strongest emission intensity leading to the yellow emission with the CIE chromaticity coordinates (0.441, 0.475). The optimal concentration of Dy 3+ was found to be 8%. The luminescence decay lifetime for 4 G 5/2 → 6 H 13/2 transition of Dy 3+ was of millisecond level and decreased with the increase in Dy 3+ ion concentration. The obtained results indicated that NaLaMgWO 6 :Dy 3+ phosphor could be a potential yellow emitting phosphor for possible application in w-LEDs. [ABSTRACT FROM AUTHOR]

In this paper, we reported a type of highly luminescent YVO 4 :Eu 3+ @YVO 4 core–shell nanoparticles (NPs) obtained by a surface-confined thermal diffusion method. YVO 4 :Eu 3+ particle cores with a doping ratio of 50% were firstly synthesized, followed by the regrowth of pure YVO 4 shells. Thereafter, the raw YVO 4 :Eu 3+ @YVO 4 core–shell NPs were embedded into a silica xerogel, which underwent annealing at 800 °C for different times. Thanks to the protection of silica matrix and thermal diffusion of Eu 3+ , the as-obtained optimal NPs maintained the initial small size (19 nm), but exhibited considerably improved luminescent properties: the intensity was enhanced by 13 times and absolute quantum yield raised up to 14.4%. Such a good performance was interpreted by the corporation of three factors, i.e. improved crystallization, decreased concentration quenching and absent surface quenching. [ABSTRACT FROM AUTHOR]

Abstract: A series of green-emitting phosphors with the formula Ba1−x Eu x Si3O4N2 (x=0.02, 0.04, 0.06, 0.08, 0.10, 0.15, 0.25) were synthesized successfully by solid state reactions. The phosphors exhibited strong green emission upon the excitation in the range of 250–480nm, matching with the emission bands of the near ultraviolet and the blue LED chips. Combined Ba0.94Eu0.06Si3O4N2 with Sr2Si5N8:Eu2+ and YAG:Ce3+ phosphors for the blue LED, the obtained emission spectrum was analogous to the solar emission spectrum. Because evolution has produced human eyes being optimized to match the solar emission spectrum, Ba1−x Si3O4N2:xEu2+ is a promising candidate of green-emitting phosphor for eye health white LEDs. [Copyright &y& Elsevier]

Abstract: Ba3Si6O12N2 green-emitting phosphors were synthesized using oxide precursor by liquid phase precursor (LPP) method under a flowing NH3 gas. X-ray diffraction patterns showed that the prepared phosphor indicated a Ba3Si6O12N2 pure single phase. The emission spectra of synthesized phosphors under excited from UV to blue light showed a typically broad green emission wavelength which is assigned to 4f65d→4f7 electronic transition of Eu2+ ion. Compared with emission intensity of prepared sample, the emission intensity of Ba3Si6O12N2 green-emitting phosphors using LPP method is more than 2.5 times than that of Ba3Si6O12N2 green-emitting one by a solid state reaction method. The synthesis of phosphor using the LPP method is expected as alternative synthesis method. [Copyright &y& Elsevier]

Abstract: AlN-substituted in Y3Al5O12: Ce3+ phosphor was synthesized to improve the phosphor efficiency of phosphor-converted white light emitting diodes. The photoluminescence properties of AlN-substitued for Al2O3 in Y3Al5O12: Ce3+ phosphor showed excellent green to yellow emission intensity under 460nm. The highest emission intensity was observed at an AlN concentration of 0.3mol and a Ce3+ concentration in the optimized flux of 0.20mol. The green to yellow emitting AlN-substituted in Y3Al5O12: Ce3+ phosphor can be applied to white LEDs. [Copyright &y& Elsevier]

Abstract: Eu2+-activated Ba3Si6O12N2 green-emitting phosphors were synthesized by a solid-state reaction method. X-ray diffraction patterns showed that the synthesized phosphor sintered at 1200°C for 12h was a Ba3Si6O12N2 pure phase. The synthesized phosphors were excited in UV to blue light. The emission spectra showed a broad green emission band when excited with a light at 465nm. The highest emission intensity was observed at a Eu2+ concentration of 0.25mol and the NH4Cl concentration of the optimized flux was found to be 9wt.%. The obtained green-emitting Ba3Si6O12N2:Eu2+ phosphors could be applied to white LED applications. [Copyright &y& Elsevier]

Abstract: Aluminum oxynitride(AlON) phosphors co-doped by Tb3+ and Ce3+ were synthesized by nitridation of the precursor which was co-precipitated from Al(NO3)3 solution and nanosized carbon black at 1750°C for 2"hrs" in flowing nitrogen atmosphere. The obtained AlON based powders were composed of polycrystalline spinel typed particles with sizes in the range of 1–3μm. Under an excitation of 275nm, it was found that co-doping of Ce3+ could drastically enhance the luminescence of AlON:Tb3+ powder by energy transfer. The product with 0.5mol% Ce3+ and 0.67mol% Tb3+ exhibited a strong broad green emission at 540nm. The critical quenching concentration of Tb3+ in AlON:0.5mol% Ce3+/xmol% Tb3+ phosphor was determined to be 0.67mol%. It was supposed that the mechanism of concentration quenching of Tb3+ in AlON:0.5mol% Ce3+ xmol% Tb3+ phosphor was dipole–dipole interaction. [Copyright &y& Elsevier]

Abstract: Eu2+–Mg2+ co-doped AlON phosphors were prepared by a solid-state reaction route. Their structure and photoluminescence properties were studied. The substitution of Al by Mg favored the formation of pure spinel-type AlON phase and the incorporation of Eu into AlON crystal lattice. Second phase appeared in Eu containing powders. Under ultraviolet excitation at 310 nm, 3% Eu2+–10% Mg2+ co-doped phosphors exhibited a strong broad emission band in the wavelength range of 430–620 nm with a maximum at about 490 nm assigned to the typical 4f65d1–4f7 transition of the Eu2+ ion. Red shift of the emission peak is observed as the increase of Eu2+ concentration due to interaction between Eu2+ ions. [Copyright &y& Elsevier]