Investigation of the influence of active dopant and co-dopant on the luminescent properties of the phosphor based on calcium aluminate

In the present study the luminescent properties of calcium aluminate activated by Eu3+ and Dy3+ions are investigated. The phosphor on the basis of calcium aluminate was obtained via citric-nitrate sol gel method using a microwave radiation. It was determined by X-ray diffraction method and by electron microprobe analysis that rare earth elements (REE) ions incorporate into lattice of calcium aluminate and don’t form own phases. Luminescent properties of calcium aluminate activated by REE ions were studied by spectrofluorimeter. Luminescent spectrum of Ca0,95Eu0,05Al2O4 contains five bands groups of emission between 580–710 nm which correspond to 5D0 – 7Fj transitions of Eu3+(λ=254 nm). Present maxima lie in the red area of the spectrum and determine the obtainment of red glow phosphor. Excitation spectrum of Ca0,95Dy0,05Al2O4 contains two bands with maxima at 240 and 380 nm. Exciting the sample by the far ultraviolet (240 nm), two bands with maxima at 420 and 490 nm conditioning a blue glow of phosphor under overlapping of violet (4G11/2 – 6H15/2 transition of Dy3+) and blue-green (4F9/2 – 6H15/2 transition of Dy3+) radiations, respectively, were observed. Exciting the sample by the near ultraviolet (380 nm), one intense band at 420 nm and bright violet glowing were observed. Emission spectrum of the phosphor obtaining by co-activation of calcium aluminate by two test REE ions is identical to the emission spectrum of calcium aluminate activated by Dy3+ ions. Transitions of Eu3+ in this case are not observed. Nevertheless, the increase of band intensity conditioning more bright violet glowing was observed