Manganese doped zinc silicate phosphors (Zn2SiO4:Mn) were synthesized by a co-precipitation method combined with a furnace firing. This paper includes the synthesis and investigation of how the annealing temperature and concentration affect the photoluminescence properties of the Mn2+ ions in Zn2SiO4 crystals. At various firing temperatures, two different crystallographic modifications of Zn2SiO4 can be realized. The XRD pattern shows that beta-Zn2SiO4 is metastable, since it completely converts to alpha-Zn2SiO4 at 900oC. The synthesized phosphor that consists of alpha-Zn2SiO4:Mn emits a green luminescence band at 525 nm, the synthesized phosphor that consists of beta-Zn2SiO4:Mn emits a yellow luminescence band at 576 nm when excited by 325nm wavelength. The luminescence intensity is strongly dependent on the manganese doping concentrations
the optimal doping concentration is 1 mol percent. The result further confirms that Zn2+ ions can be replaced by Mn2+ ions within zinc silicate lattice. The micro-structure examined by TEM shows that the particles were spherical and highly dispersed with particle size of 40 nm.