Emission tuning studies in BaMgSiO4:RE (REÂ = Eu2+, Sr2+) for white LEDs

Color tuning is a challenge for improving white light LEDs. In this paper, the color tuning in Ba1-xMgSiO4:xEu2+ (0 ≤ x ≤ 0.07) and Ba0.993-yMgSiO4:0.007Eu2+, ySr2+ (0 ≤ y ≤ 0.07) are investigated. The emission can be tuned by increasing Eu2+ concentration and substitution of the host lattice cation Ba2+ by Sr2+. The emission shows a red shift in Ba1-xMgSiO4:xEu2+ with the increase of Eu2+ concentration. The red shift results from the preferential occupation of Eu2+. On the contrary, the emission of Ba0.993-yMgSiO4:0.007Eu2+, ySr2+ shows a blue shift when partial substitution of Ba2+ by Sr2+. The blue shift is explained by the preferential occupation of Sr2+, crystal field splitting of Eu2+ and the electron binding energy of Eu-O.