Enhanced photoluminescence properties of orange emitting Sr2.96−xBaxSiO5: Eu2+ phosphors synthesized with Sr2SiO4 as precursor

Orange emitting Sr2.96−xBaxSiO5: Eu2+ phosphors have been synthesized by a method using Sr2SiO4 instead of simple oxides and carbonate as precursor. The photoluminescence properties, radiative lifetime and formation process were investigated by PL spectra, lifetime decay and XRD analysis, respectively. X-ray diffraction analysis indicates that the phosphor has a single phase of Sr3SiO5 without residual Sr2SiO4 and BaSi4O9 phases. Under 460 nm excitation, the emission band of Sr2.96−xBaxSiO5: Eu2+ has a red-shift from 580-598 nm due to varied Ba2+ concentration. Particularly, the emission intensity of Sr2.56Ba0.4SiO5: 0.02Eu2+ sample increased significantly in comparison with the commercial SSE phosphor. The radiative lifetime τ0 are estimated to be 1.999, 2.316, 2.716 and 2.932 μs for samples of x=0, 0.2, 0.4 and 0.6, respectively. It indicates that Eu2+ ions are in different surroundings and the Sr2+ sites were substituted by Ba2+ completely. Compare with the conventional solid-state reaction method, the Sr2.96−xBaxSiO5: Eu2+ phosphors synthesized by this method show higher crystallinity and more efficient orange emission.