Preparation and spectroscopic investigation of novel NaAlP2O7:Eu2+ phosphors for white LEDs

• Phosphors NaAlP2O7:Eu2+ were synthesized for the first time.
• Structural and luminescent properties of as-synthesized phosphors were investigated.
• The temperature dependence of photoluminescence properties was investigated.
• The concentration-quenching mechanism can be explained by the electric dipole-dipole interaction of the Eu2+ ions.

NaAlP2O7:Eu2+ phosphors were prepared by a solid state reaction. The structure, Fourier transform infrared spectra, photoluminescence spectra and fluorescence decay curves of NaAlP2O7:Eu2+ were investigated. These phosphors can be excited over a broad range and generate a greenish-blue emission band peaking at 459 nm. The critical quenching concentration of Eu2+ in NaAlP2O7:Eu2+ phosphors is about 3 mol% and the corresponding concentration quenching mechanism is demonstrated to be dipole-dipole interactions. Meanwhile the critical distance for concentration quenching is determined to be 19.7 Å. As the temperature increases from 25 to 150 °C, the emission intensity of NaAlP2O7:0.03Eu2+ still possesses 86.7% of its initial PL intensity, indicating its high thermal stability. All the results suggest that the NaAlP2O7:Eu2+ phosphors are promising greenish-blue-emitting phosphors for application in white light emitting diodes.