Luminescence Properties of CaAl2O4:Eu3+, Gd3+ Phosphors Synthesized by Combustion Synthesis Method

Abstract

[EN] CaAl2O4:Eu3+ (1 mol.%) co-doped with varying concentration of Gd3+ (1, 2, 5, and 10 mol.%) were prepared by combustion synthesis method at 600 C and further annealed at 1000 ºC. All the compositions were investigated for their structural and photoluminescence properties. It was observed that both states of europium i.e. Eu3+ and Eu2+ were present and ratio of these states changes on heating at 1000 ºC. The materials synthesized at 600 ºC showed high intense peak around 440 nm due to presence of Eu2+ and less intense peaks in the red region which were due to presence of Eu3+. On annealing the compounds at 1000 ºC, intensity of peak around 440 nm decreases and intensity of peaks in the red region increases significantly. The 5D0 !7 F3 transition due to Eu3+ at 657 nm appears as the highest intensity peak. All co-doped samples annealed at 1000 ºC showed the higher intensity than the mono doped sample which is due to energy transfer from the Gd3+ to Eu3+. The second rare-earth ion (Gd3+) acts as sensitizer and enhances the photoluminescence intensity. The X-ray diffraction spectra reveal the monoclinic phase of CaAl2O4 in all the samples which showed that Eu3+ and Gd3+ do not change the crystalline structure of calcium aluminate.