Crystal structure of EU2+-doped M3MgSi2O2 (M: Ba, Sr, Ca) compounds and their emission properties

Emission properties of Eu2+-doped M3MgSi2O8 (M: Ba, Sr, Ca) are discussed in terms of the crystal structure. When Ba2+ ions account for over one third of M2+ ions, M3MgSi2O8 crystallize in glaserite-type trigonal structure, while Ba-free compounds crytallize in merwinite-type monoclinic Structure. Under UV excitation, the Eu2+-doped glaserite-type Compounds exhibit an intense blue emission assigned to 5d-4f electron transition at about 435 nm, regardless of the molar ratio of Ba2+, Sr2+ and Ca2+ ions. By contrast, the Eu2+-doped merwinite-type compounds show an emission color sensitive to the ratio. A detailed analysis of the emission spectra reveals that the emission chromaticity for the Eu2+-doped M3MgSi2O8 is composed of two emission peaks reflecting two different sites accommodating M2+ ion. (C) 2008 Elsevier Inc. All rights reserved.