Pyrolysis synthesis of Zn2SiO4:Mn2+ phosphors - effect of fuel, flux and co-dopants

Green emitting α-Zn2SiO4:Mn2+ phosphors were made by pyrolysis route at 600 °C followed by sintering at a moderate temperature of 1000 °C for 1 h duration. The effects of different fuels (urea, citric acid, polyethylene glycol and glycine), flux materials (H3BO3, NH4Cl, NH4F, NH4Br, BaCl2, BaBr2, CaF2 and BaF2), divalant co-dopants (Ca2+, Ba2+, Mg2+ and Sr2+), trivalent co-dopants (Al3+, Y3+ and Gd3+) and sintering temperature (800-1000 °C) on the photoluminescence (PL) efficiency of Zn2SiO4:Mn2+ were studied. Among the fuels, urea and among the flux, H3BO3 gave a maximum broad band green PL emission peak at 525 nm on excitation at 254 nm. Divalent co-dopants improved the PL intensity much more than the trivalent co-dopants used. Highest PL efficiency was observed with Sr2+ co-doped Zn2SiO4:Mn2+ sintered at 1000 °C in reducing atmosphere which was 20% higher than that of the commercial Zn2SiO4:Mn2+. The formation of a single crystalline phase of willemite structure in the α-Zn2SiO4:Mn2+ samples synthesized was confirmed by powder XRD measurements.