Novel method for the synthesis of Dy-doped yttrium disilicate phosphoros

Abstract

The complex high temperature polymorphism (Y, α, β, γ and δ structures) of yttrium disilicate (Y2Si2O7) naturally lead to relatively broad emission, originating from ions placed in different symmetry sites, for example, the replacing of Y3+ by rare earth ions. Y2Si2O7 as the host lattice shows a high thermal and chemical stability compared with other well-studied phosphors such as ZnS and CdS. When doped with different metallic ions, yttrium silicates exhibit attractive luminescent properties for potential applications, such as plasma displays, laser materials and high-energy phosphors. The sol-gel technique provides an available method to prepare ceramic powders, with higher purity and homogeneity compared to the conventional solid-state reaction of mixed oxides. In the present work, a novel sol-gel and co-precipitation combined method has been proposed for synthesis of RE3+ doped Y2Si2O7 (RE=Dy). Silica nanoparticles were obtained by surfactant-assisted sol-gel process, using sodium silicate (Na2SiO3) as precursor, and then Y3+ and Dy3+ ions were precipitated over these particles. The RE3+:Y2Si2O7 obtained product was analyzed by SEM, XRD and luminescence spectroscopy. Crystalline Y2Si2O7 was obtained at lower temperatures compared with traditional methods. The α-phase was obtained at 1100 and 1200°C, and β-phase at 1300°C. Comparing photoluminescence spectra of α and β-phases, the later showed higher intensity luminescence peaks.