Preparation And Luminescence Properties Of Rare-earth-doped Silicon-based Oxynitride Phosphors

This paper aims at looking for cost-effective, high quality and wide applicable red rare-earth-doped silicon-based oxynitride fluorescent materials. These studies will carry out from the following two aspects:1. A series of disordered a'-Sr2SiNzO4-1.5z:Eu2+(0? z? 1.333) and a'-Si3x/4O2Nx: Eu2+(1.333? x? 2.4) (a'-SSON:Eu2+) phosphors were synthesized by the conventional solid state reaction method. We investigated the N3- ions effects on the crystal structural and luminescent properties of a'-SSON:Eu2+ by varying N content, and also interpreted the emssion intensity change and red-shift phenomenon of the disordered a'-SSON:Eu2+. With the increase of N concentration, both the luminescence intensity and the dominant peak wavelengths (DPWs, which is about 490 nm) of Eu(I) site were extraordinarily unchanged. In comparison with the yellow emissions (-580 nm) of Eu(II) site of the disordered a'-Sr2Si04:Eu2+, the DPWs of Eu(II) emissions were at red spectral regions (609-618 nm), which depends on the amount of N3-. The existence of N3" ions are verified by the analyses of XRD refinement data, FT-IR spectra, N/O element content, photoluminescence (PL) and absorption spectra of disordered a'-SSON:Eu2+.2. The crystal of Sr1.98-xBaxSi(O,N)4:0.02Eu2+(0? x? 0.5, SBSON:0.02Eu2+) could be effectively controlled by Ba2+doping and could achieve high and tuned PL intensity of SSON:Eu2+based on modification of the crystal structure. We investigated the effects of Ba2+substitution on the crystal structural and luminescence properties of SSON:Eu2+by varying Ba2+content. It indicate that Ba2+doping can lead to the results that Sr1.98Si(O,N)4:0.02Eu2+transform from ? to a'phase successfully. The analysis of crystal structure of a'-Sr1.98Ba0.1Si(O,N)4:0.02Eu2+ suggest that it is mixture of ordered and disordered a'phase. After phase transformation, with the increase of Ba2+content, the PL intensity gradually increased under 375 nm and gradually declined under 460 nm excitation. Whereas Ba2+doping led to an obvious blue-shift both under 375 nm and 460 nm excitation. This paper interpretate the specific reasons of phase transformation, the change of PL intensity and blue-shift. The site of N3- substituting for O2- and thermal quenching mechanism of SBSON:0.02Eu2+are determined effectively.3. The p-Sr1.98SiO4-1.5xNx:0.02Eu2+(?-SSON:0.02Eu2+, x=0,0.3,0.6,0.9,1.2 and 4/3) have been synthesized by a traditional high temperature solid state reaction method. We investigated the effects of N3- ions substitution on the crystal structural and luminescence properties of ?-SSON:Eu2+by varying N3- content. The distributive sites in crystal structure of different emission bands, the specific explanation of red emission, the concentration quenching mechanism have been studied effectively. This work suggests that the incorporation of N3" in P-Sr2SiO4: Eu2+phosphor is an effective method for the regulation of various emission bands in order to obtain a richer luminescence.