Thermal quenching mechanisms of the Eu3+ luminescence in Ca9Al(PO4)7 obtained by citric route

The citric route was employed for synthesis of the pure phase Ca9Al(PO4)7:Eu3+ (CAlP:Eu3+) powders as an attractive alternative to the solid state reaction (no need of multistep and long thermal treatment). Structural properties of the final product were studied by means of X-ray diffraction as well as Rietveld refinement was conducted in order to calculate the cell parameters. The thermal behavior of the emission was studied using excitation line well matched with the 7F0 → 5D4 absorption band covering broad range of temperature. Activation energy was estimated to be equal to 10,550 cm−1. The thermal behavior of the Eu3+ luminescence in CAlP crystal lattice shown that the almost 80% of intensity is kept up to 430 K.

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► Convenient citric route was used for preparation of the Ca9Al(PO4)7:Eu3+ powders.
► We found that the thermal dependency of the Eu3+ emission shows two different temperature ranges.
► 80% of Eu3+ luminescence intensity is kept at 430 K.
► The possible quenching pathways were constructed using simplified one coordinate energy diagram.