Effect of Eu ³⁺ concentration on microstructure and photoluminescence of Sr ₂SiO ₄:Eu ³⁺ phosphors prepared by microwave assisted sintering

In this paper, effect of Eu ³⁺ doping concentrations on microstructure and photoluminescence of Sr ₂SiO ₄ phosphors was investigated. The Sr _2-xSiO ₄:xEu ³⁺ phosphors with x=0.05, 0.1, 0.2, 0.3 were synthesized by microwave assisted sintering at 1200°C for 60 min in air. X-ray powder diffraction analysis confirmed the formation of pure Sr ₂SiO ₄ phase without second phase or phases of starting materials irrespective of the adding amount of Eu ³⁺. From scanning electron microscopy image, it is found that with more Eu ³⁺ ions introduced to Sr ₂SiO ₄, the shape of the particles is not much different from each other, but the particle size decreases significantly from 1 to 2 μm (when x=0.05) to less than 500 nm (when x=0.3). The emission spectrum was located obviously at 617 nm as the excitation spectrum at λ _ex=395 nm, and it had best emission intensity when x=0.1.