Structure and photoluminescence properties of SrSi₂O₂N₂: Eu²⁺ phosphors prepared by two-step solid state reaction using Sr₂SiO₄: Eu²⁺ as a precursor

Abstract

A series of yellow green emitting phosphors nitrogen oxides Sr₁_{-<italic>x</italic>}Si₂O₂N₂:Eu<italic>_x</italic>²⁺(0.02≤<italic>x</italic>≤0.10) were synthesized by a method using Sr₂SiO₄:Eu²⁺ as a precursor and their photoluminescence properties and reaction mechanism were investigated in detail. The photoluminescence results show that all samples can be excited efficiently by UV (400 nm) light and blue (450 nm) light and emit yellow green (535 nm) light with line spectra, which are coupled well with the characteristic emission from UV-LED and blue LED, respectively. The experimental results and their analysis suggest that the optimum concentration of Eu²⁺ is 0.05 mol and the energy transfer occurs due to dipole-dipole interactions among Eu²⁺ ions in Sr₁_{-<italic>x</italic>} Si₂O₂N₂:Eu<italic>_x</italic>²⁺, the critical distance (<italic>R</italic>_c) of energy transfer was calculated to be about 1.507 nm. Furthermore, the thermal stability and the emission intensity of synthesized SrSi₂O₂N₂:Eu²⁺ phosphor was examined and compared with that of commercial YAG yellow phosphors. All the results indicate that the phosphor is a suitable candidate of yellow green emitting phosphor for the fabrication of white LEDs.

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