Luminescence properties of green emission of SiO2/Zn2SiO4:Mn nanocomposite prepared by sol–gel method

Abstract

Green light emitting Mn2+ doped Zn2SiO4 particles embedded in SiO2 host matrix were synthesized by a sol–gel method. After the incorporation of ZnO:Mn nanoparticles in a silica monolith using sol–gel method with supercritical drying of ethyl alcohol in two steps, it was heat treated in air at 1200°C for 2h in order to obtain the SiO2/α-Zn2SiO4:Mn nanocomposites. The microstructure of phosphor crystals was characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). XRD results indicate that the pure phase α-Zn2SiO4 with rhombohedral structure was obtained after thermal treatment at 1200°C. The SiO2/α-Zn2SiO4:Mn nanocomposites with a Mn doping concentration of 1.5at% exhibit two broadband emissions in the visible range: a strong green emission at around 525nm and a second one in the range between 560 and 608nm. This nanocomposite with a Mn doping concentration of 0.05 shows the highest relative emission intensity. Upon 255nm excitation, the luminescence decay time of the green emission of Zn2SiO4:Mn around 525nm is 11ms. The luminescence spectra at 525nm (4T1–6A1) and lifetime of the excited state of Mn2+ ions-doped Zn2SiO4 nanocrystals are investigated.