Synthesis and luminescent properties of Mn2+-doped zinc silicate phosphors by sol–gel methods

Green light emitting Mn2+-doped Zn2SiO4 phosphor nano-particles were synthesized by a sol–gel method combined with a furnace firing. All samples were prepared at various temperatures and times both with and without a polymeric surfactant to determine if the particle size can be tailor-made over a significant range. The particle size of all the powder samples was measured through dynamic light scattering, which showed a mean particle diameter between 30 nm and 1 μm depending on the conditions. Final manganese amounts were determined by inductively coupled plasma spectroscopy. The microstructure of phosphor crystals was characterized by X-ray diffractometry (XRD) and scanning electron microscopy. XRD results indicate that seeds play an important role in enhancing the nucleation and crystallization of Zn2SiO4:Mn2+. Green photoluminescence (PL) and cathodoluminescence (CL), whose emission peak is located at 522 nm, were observed from the synthesized phosphor particles under UV excitation and electron bombardment. Results show that the non-seeded samples with a mean diameter of 30 nm displayed a significant increase in PL brightness over the seeded samples whose mean diameter was 215 nm. In contrast, XRD results show that the seeded samples were more crystalline than the non-seeded samples. PL and CL intensity lagged behind the bulk reference sample due to a high manganese loss in processing.