Syntheses and optical properties of α- and β-Zn2SiO4: Mn nanoparticles by solvothermal method in ethylene glycol-water system

Mn doped Zn2SiO4 phosphors (Zn2SiO4:Mn) with different morphologies and crystal structures, exhibiting different luminescence, were synthesized via a low-temperature solvothermal method in ethylene glycol-water system. Powder X-ray (XRD) and scanning electron microscopy (SEM) were used to characterize the phase purity, particle size and morphology. Photoluminescence (PL) spectra were collected and analyzed. The usual a-phase Zn2SiO4:Mn exhibited green emission centered at about 525 nm while the yellow emission centered at 563 nm resulted from P-phase Zn2SiO4:Mn. In situ XRD measurement results showed that the phase transfers from yellow to green phosphor at high temperature. The dependence of the emission intensity on the Mn2+ doping concentration was also investigated, showing that the optimum doping concentrations were relatively low. XPS analysis revealed the red shifts for both Mn 2p(3/2) and Zn 2p(3/2) binding energies in yellow phosphor. The shifts might indicate Zn2+ and doped Mn2+ ions in beta-Zn2SiO4:Mn adopt different coordination environments from tetrahedral case that is adopted in alpha-Zn2SiO4:Mn. (c) 2009 Elsevier B.V. All rights reserved.