K 2 TiF 6 :Mn 4+ is an attractive narrow-band red-emitting phosphor for warm white light-emitting diodes (LEDs). Nevertheless, the hexafluoride phosphor is liable to deliquesce in moist environments, which leads to a sharp deterioration performance of luminescence. Surface modification of K 2 TiF 6 :Mn 4+ phosphor with SrF 2 coating has been introduced, with the aid of KHF 2 transition layer to moderate the lattice mismatch. The reaction mechanism is discussed in detail, as so as the influence of SrF 2 coating on the luminescence intensity. The SrF 2 coating is able to prevent the hydrolysis of internal [MnF 6 ] 2− group; thereby, the luminescence intensity retains over 90% of initial value after being immersed in distilled water for 2 h. The LED devices fabricated with commercial Y 3 Al 5 O 12 :Ce 3+ and as-modified K 2 TiF 6 :Mn 4+ phosphors exhibit bright white light with tunable chromaticity coordinate, correlated color temperature, and color rendering index. It enlightens a convenient method to enhance the moisture resistance of Mn 4+ doped fluoride phosphors for commercial application in the field of white LEDs.

Bi3+-activated luminescence materials have gained growing attentions for optoelectronic applications. In this work, a novel BaLu2MgGa2Si2O12: Bi3+ garnet phosphor was synthesized through a traditional high-temperature solid phase reaction method. The crystal structure was ascertained through X-ray diffraction analysis and Rietveld structural refinement. The particle morphology and constituent elements distributions were investigated through scanning electron microscope and element mapping. Excited at 330 or 370 nm, the phosphors exhibit two emission peaks located at 413 and 495 nm, which is ascribed to the allowed transitions of Bi3+: 3P1 → 1S0. The luminescence intensity reaches the maximum at the 4 mol% Bi3+ doping content, and the emission color is easily manipulated by tuning the excitation wavelength. Besides, the luminescence intensity at 150 ℃ remains 80% of that at room temperature. These results suggest that the novel phosphors have promising application in the near-UV excited white LEDs.

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