Temperature dependence of the luminescence of calcium-magnesium phosphate Ca3Mg3(PO4)4:Eu2+, a blue-emitting material for white light-emitting diodes

• Emission spectrum at 20 K confirms that Eu2+ ions occupy three sites.
• Decay curves of three types of Eu2+ reflect the characteristics of energy transfer.
• The Eu(I) emission is thermally quenched at 323 K.
• Ca3Mg3(PO4)4:Eu2+ has good thermal stability.
• Ca3Mg3(PO4)4:Eu2+ is a promising phosphor for near UV excited white LEDs.

A blue-emitting phosphor Ca3Mg3(PO4)4:Eu2+ peaking at 450 nm was synthesized by a solid state reaction. The XRD patterns, luminescence properties, decay curves of samples as well as their thermal quenching and comparing the luminescence properties with that of commercial material were investigated. At 20 K, the emission spectrum exhibiting two distinct bands peaking at 437 and 473 nm with a shoulder peak at 510 nm can be attributed to the overlap of Eu(I), Eu(II) and Eu(III) emission bands. At 423 K the PL intensity decreases to 80% of the value at room temperature, and the emission wavelength shifts toward high energy. The derived activation energy indicates that the lowest energy level of the Eu2+ 4f65d1 state is well isolated from the host lattice conduction band. The PL spectra and chromaticity coordinates are close to those of BAM. Ca3Mg3(PO4)4:Eu2+ could be a potential candidate for near-UV excited white LEDs.

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