Y2CaAlGe(AlO4)3:Ce and Y2MgAlGe(AlO4)3:Ce garnet phosphors for white LEDs

New phosphors with the compositions Y2CaAlGe(AlO4)3:Ce and Y2MgAlGe(AlO4)3:Ce were obtained by co-precipitation technique. Their structural, morphological and luminescence properties were investigated. The 2Θ shift observed in XRD patterns was attributed to the substitution of Y3+ and Al3+ ions by Ca2+ (Mg2+) and Ge4+ ions, respectively. It was shown that the composition of the new polycrystalline compounds is uniform. Both new phosphors exhibit a broad luminescence band, as usual for the Ce3+ ion emission in garnets. A shift of the band was observed and attributed to the different crystal field experienced by the Ce3+ ions in inequivalent sites in the complex garnets.