Synthesis and photoluminescence enhancement of the LiLa(MoO4 )2 :Sm3+ red phosphors by co-doping with Bi3.

The LiLa(MoO4 )2 :Sm3+ and LiLa(MoO4 )2 :Sm3+ ,Bi3+ phosphors were prepared using the citric-acid-fueled combustion method and the influence of concentrations of Bi3+ dopant on LiLa(MoO4 )2 :Sm3+ red luminescence was investigated. The LiLa(MoO4 )2 :Sm3+ and LiLa(MoO4 )2 :Sm3+ ,Bi3+ samples matched well with the scheelite structure and I41 /a space group and did not detect structural changes. Under an excitation of 403 nm, the prepared LiLa(MoO4 )2 :Sm3+ ,Bi3+ phosphor was excited and produced orange-red emission. When compared with the LiLa(MoO4 )2 :Sm3+ phosphor, the LiLa(MoO4 )2 :Sm3+ ,Bi3+ phosphor exhibited enhanced fluorescence intensity because the Bi3+ dopant ions are doped as a sensitizer. The optimal doping concentrations of Sm3+ and Bi3+ were 5 and 1 mol%, respectively. Furthermore, the energy transfer from Bi3+ to Sm3+ is effective (3 P1 → 4 K11/2 ). Subsequently, the electrons in an unstable excited state were transferred to a stable ground state (4 G5/2 → 6 H5/2 , 6 H7/2 , 6 H9/2 ). The Commission Internationale de L'Eclairage (CIE) chromaticity coordinates of the optimized LiLa(MoO4 )2 :Sm3+ ,Bi3+ phosphor were situated in the orange-red region. The luminescence of the LiLa(MoO4 )2 :Sm3+ ,Bi3+ phosphor generated under near-ultraviolet (UV) irradiation could be used to produce a warm white light, indicating its possible applications in white light-emitting diodes.

Enhancement of the luminescence properties of Sr3 (PO4 )2 :Dy3+ ,Li+ white-light-emitting phosphors by charge compensator Li+ co-doping.

Sr3 (PO4 )2 :Dy3+ ,Li+ phosphors were prepared using a simple high temperature solid method for luminescence enhancement. The structures of the as-prepared samples agreed well with the standard phase of Sr3 (PO4 )2 , even when Dy3+ and Li+ were introduced. Under ultraviolet excitation at 350 nm, the Sr3 (PO4 )2 :Dy3+ sample exhibited two emission peaks at 483 nm and 580 nm, which were due to the 4 F9/2  â†’ 6 H15/2 and 4 F9/2  â†’ 6 H13/2 transitions of Dy3+ ions, respectively. A white light was fabricated using these two emissions from the Sr3 (PO4 )2 :Dy3+ phosphors. The luminescence properties of Sr3 (PO4 )2 :Dy3+ ,Li+ phosphors, including emission intensity and decay time, were improved remarkably with the addition of Li+ as the charge compensator, which would promote their application in near-ultraviolet excited white-light-emitting diodes.

Synthesis and photoluminescence characteristics of Sm3+ -doped Bi4 Si3 O12 red-emitting phosphor.

A series of novel red-emitting Sm3+ -doped bismuth silicate phosphors, Bi4 Si3 O12 :xSm3+ (0.01 ≤ x ≤ 0.06), were prepared via the sol-gel route. The phase of the synthesized samples calcinated at 800 °C is isostructural with Bi4 Si3 O12 according to X-ray diffraction results. Under excitation with 405 nm light, some typical peaks of Sm3+ ions centered at 566, 609, 655 and 715 nm are found in the emission spectra of the Sm3+ -doped Bi4 Si3 O12 phosphors. The strongest peak located at 609 nm is due to 4 G5/2 -6 H7/2 transition of Sm3+ . The luminescence intensity reaches its maximum value when the Sm3+ ion content is 4 mol%. The results suggest that Bi4 Si3 O12 :Sm3+ may be a potential red phosphor for white light-emitting diodes. Copyright © 2016 John Wiley & Sons, Ltd.