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Up-conversion phosphors BaLa 2 ZnO 5 co-doped with Ho 3+ /Yb 3+ were synthesized by high temperature solid-state reaction method. The phase composition of the phosphors was characterized by X-ray diffraction (XRD). The structure of BaLa 2 ZnO 5 : 0.75% Ho/15% Yb phosphor was refined by the Rietveld method and results showed the decreased unit cell parameters and cell volume after doping Ho 3+ and Yb 3+ , indicating Ho 3+ and Yb 3+ have successfully replaced La 3+ . Under the excitation of 980 nm diode laser, the strong green and weak red up-conversion emissions centered at 548 nm, 664 nm and 758 nm were observed, which originating from 5 S 2 , 5 F 2 → 5 I 8 , 5 F 4 → 5 I 8 and 5 S 2 , 5 F 2 → 5 I 7 transitions of Ho 3+ ions, respectively. The optimum doping concentrations of Ho 3+ and Yb 3+ were determined to be 0.75% and 15%, and the corresponding Commission International de L'Eclairage (CIE) coordinates are calculated to be x =0.298 and y =0.692. The related UC mechanism of Ho 3+ /Yb 3+ co-doped BaLa 2 ZnO 5 depending on pump power was studied in detail. The results indicate that BaLa 2 ZnO 5 : Ho 3+ /Yb 3+ can be an effective candidate for up-conversion yellowish-green light emitter. [ABSTRACT FROM AUTHOR]

A series of Eu 2+ and Eu 2+ /Tb 3+ co-doped Ba 3 GdNa(PO 4 ) 3 F phosphors have been synthesized via a high temperature solid-state reaction. The relative intensity of PL spectra of Ba 3 GdNa(PO 4 ) 3 F: x Eu 2+ increases with increasing x value, and reaches a maximum at x =0.04. Ba 3 GdNa(PO 4 ) 3 F:Eu 2+ , Tb 3+ phosphors exhibit a broad excitation band ranging from 220 to 450 nm, which matches perfectly with the characteristic emission of n -UV light-emitting diode (LED) chips. Upon 365 nm excitation, the Ba 3 GdNa(PO 4 ) 3 F:Eu 2+ , Tb 3+ phosphors show two dominating bands peaked at 466 and 543 nm, which are assigned to the 4f 7 →4f 6 5d 1 transition of the Eu 2+ ions and the 5 D 4 → 7 F 5 transition of the Tb 3+ ions, respectively. In view of the energy transfer mechanism between Eu 2+ and Tb 3+ , the Ba 3 GdNa(PO 4 ) 3 F:Eu 2+ , Tb 3+ emission color can adjust from blue to green, and their chromatic coordinates ( x , y ) vary from (0.16, 0.135) to (0.254, 0.398). The critical distance was also calculated to be 16.90 Å. The above results indicate that the Ba 3 GdNa(PO 4 ) 3 F: Eu 2+ , Tb 3+ phosphors are a candidate for blue–green components in the application of n -UV w -LEDs. [ABSTRACT FROM AUTHOR]