Characterization and photoluminescence properties of some CaO, SrO and CaSrO2 phosphors co-doped with Eu3+ and alkali metal ions

CaO:Eu3+, M+ (Li+ or Na+ or K+), SrO:Eu3+and CaSrO2:Eu3+ powders were prepared by combustion synthesis method and the samples were further heated to ∼1000 °C to improve the crystallinity of the materials. The structure and morphology of materials were examined by X-ray diffraction and scanning electron microscopy. The morphology of CaO:Eu3+ and co-doped with alkali metal ions powders was very similar. Small and coagulated particles of nearly cubical shapes with small size distribution having smooth and regular surface were formed. The surface morphology of SrO and CaSrO2 materials was not smooth and coagulated particles of irregular shapes with different sizes were observed. The characteristic emissions of Eu3+ had strong emission at 614 and 620 nm for 5D0 → 7F2 with other weak transitions observed at 580, 592, 654, 705 nm for 5D0 → 7Fn transitions where n = 0, 1, 3, 4 respectively in all host lattices. Photoluminescence intensity followed the order as in CaO > CaSrO2 > SrO lattices. A remarkable increase of photoluminescence intensity was observed by the co-doping of alkali metal ions particularly K+ ions in CaO:Eu3+.

► CaO:Eu3+, M+ (Li+, Na+ or K+) powders prepared by combustion synthesis method.
► SrO:Eu3+ and CaSrO2:Eu3+ phosphors obtained by combustion synthesis method.
► Photoluminescence intensity varies as: CaO:Eu3+ > CaSrO2:Eu3+ > SrO:Eu3+ lattices.
► Co-doping with alkali metal, particularly K+ ions, increases photoluminescence.