Investigation of the luminescent properties of Ce3+ doped and Ce3+/Mn2+ co-doped CaAl2Si2O8 phosphors

A series of Ce3+ doped and Ce3+/Mn2+ co-doped CaAl2Si2O8 phosphors have been synthesized in a reducing atmosphere (Ar/H-2) via a solid-state route and their photoluminescent properties have been investigated at room temperature. For the CaAl2Si2O8: Ce3+ phosphor, a broad emission band at 430 nm is observed in addition to characteristic bands of Ce3+ peaking at 334 nm and 356 nm. The extra band is assigned to the presence of cationic vacancies naturally created to counterbalance the substitution of Ce3+ ions for Ca2+ alkaline-earth species. Its intensity can be significantly reduced when Ca2+ cations are replaced by the reaction 2Ca(2+) -> Ce-Ca + K-Ca'; i.e. when the amount of alkaline earth vacancies induced by the presence of Ce3+ cations is minimized. Moreover, the co-doping Ce3+/Mn2+ goes along with the appearance of energy transfers that make possible fine tuning of the CIE(x, y) parameters from blue to warm white and even yellow.