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Red-emitting Li(2)Sr(1-3x/2)Eux SiO4 0 ≤ x ≤ 0.5) phosphors were synthesized at 900 °C in air by a solid-state reaction. The synthesized phosphors were characterized by X-ray powder diffraction, photoluminescence (PL) excitation (PLE) and PL spectra. The results from the PLE spectra suggest that the strong 394 nm excitation peak associated with the (5) L6 state of Eu(3+) ions is of significance for near ultraviolet pumped white light-emitting diodes and solid-state lighting. It is also noted that the position of the charge transfer state of Eu(3+) ions shifts towards the higher energy side (blue shift) by increasing the content of Eu(3+) ions. The predominant emissions of Eu(3+) ions under 394 nm excitation are observed at 580, 593, 614, 656 and 708 nm, which are attributed to the (5) D0 → (7)FJ (J = 0, 1, 2, 3 and 4), respectively. The PL results reveal that the optimal content of the red-emitting Li2 Sr(1-3x/2)Eux SiO4 phosphors is x = 0.475. Simulation of the white light excited by 394 nm near ultraviolet light has also been carried out for its potential white light-emitting diode applications.

The Ca3−xB2O6:xDy3+ (0.0 ≤ x ≤ 0.105) and Ca2.95−yDy0.05B2O6:yLi+ (0 ≤ y ≤ 0.34) phosphors were synthesized at 1100 °C in air by solid-state reaction route. The as-synthesized phosphors were characterized by X-ray powder diffraction (XRD), scanning electron microscope (SEM), photoluminescence excitation (PLE) and photoluminescence (PL) spectra. The PLE spectra show the excitation peaks from 300 to 400 nm is due to the 4f–4f transitions of Dy3+. This mercury-free excitation is useful for solid state lighting and light-emitting diodes (LEDs). The emission of Dy3+ ions upon 350 nm excitation is observed at 480 nm (blue) due to the 4F9/2 → 6H15/2 transitions, 575 nm (yellow) due to 4F9/2 → 6H13/2 transitions and a weak 660 nm (red) due to 4F9/2 → 6H11/2 emissions, respectively. The optimal PL intensity of the Ca3−xB2O6:xDy3+ phosphors is found to be x = 0.05. Moreover, the PL results from Ca2.95−yDy0.05B2O6:yLi+ phosphors show that Dy3+ emissions can be enhanced with the increasing codopant Li+ content till y = 0.22. By simulation of white light, the CIE of the investigated phosphors can be tuned by varying the content of Li+ ions, and the optimal CIE value (0.300, 0.298) is realized when the content of Li+ ions is y = 0.22. All the results imply that the Ca2.95−yDy0.05B2O6:yLi+ phosphors could be potentially used as white LEDs.

The Ca2.95−yDy0.05B2O6:yNa+ (0≤y≤0.20) phosphors were synthesized at 1100 °C in air by the solid-state reaction route. The as-synthesized phosphors were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), photoluminescence excitation (PLE), photoluminescence (PL) spectra and thermoluminescence (TL) spectra. The PLE spectra show the excitation peaks from 300 to 400 nm due to the 4f–4f transitions of Dy3+. This mercury-free excitation is useful for solid-state lighting and light-emitting diodes (LEDs). The emission of Dy3+ ions on 350 nm excitation was observed at 480 nm (blue) due to the 4F9/2→6H15/2 transitions, 575 nm (yellow) due to 4F9/2→6H13/2 transitions and 660 nm (red) due to weak 4F9/2→6H11/2 emissions. The PL results from the investigated Ca2.95−yDy0.05B2O6:yNa+ phosphors show that Dy3+ emissions increase with the increase of the Na+ codoping ions. The integral intensity of yellow to blue (Y/B) can be tuned by controlling Na+ content. By the simulation of white light, the optimal CIE value (0.328, 0.334) can be achieved when the content of Na+-codoping ions is y=0.2. The results imply that the Ca2.95−yDy0.05B2O6:yNa+ phosphors could be potentially used as white LEDs.

Red-emitting Li(2)Sr(1-3x/2)Eux SiO4 0 ≤ x ≤ 0.5) phosphors were synthesized at 900 °C in air by a solid-state reaction. The synthesized phosphors were characterized by X-ray powder diffraction, photoluminescence (PL) excitation (PLE) and PL spectra. The results from the PLE spectra suggest that the strong 394 nm excitation peak associated with the (5) L6 state of Eu(3+) ions is of significance for near ultraviolet pumped white light-emitting diodes and solid-state lighting. It is also noted that the position of the charge transfer state of Eu(3+) ions shifts towards the higher energy side (blue shift) by increasing the content of Eu(3+) ions. The predominant emissions of Eu(3+) ions under 394 nm excitation are observed at 580, 593, 614, 656 and 708 nm, which are attributed to the (5) D0 → (7)FJ (J = 0, 1, 2, 3 and 4), respectively. The PL results reveal that the optimal content of the red-emitting Li2 Sr(1-3x/2)Eux SiO4 phosphors is x = 0.475. Simulation of the white light excited by 394 nm near ultraviolet light has also been carried out for its potential white light-emitting diode applications.