Eu-doped CaAl2Si2O8 nanocrystalline phosphors crystallized from the CaO-Al2O3-SiO2 glass system

A new process to synthesis Eu-doped CaAl2Si2O8 (CaAl2Si2O8:Eu) nanocrystals coated with SiO2 is proposed. In this process, CaAl2Si2O8:Eu nanocrystals were precipitated in a SiO2-rich matrix through phase separation and crystallization. Eu-doped CaO-Al2O3-SiO2 system glasses, with a composition of (x-1)SiO2-(100-x)CaAl2O4-1Si mol % in the immiscibility region, were prepared by a conventional melt-quenching process. They were heat-treated for phase separation and crystallization to precipitate the CaAl2Si2O8:Eu crystals into the phase separated glass. We succeeded in obtaining CaAl2Si2O8:Eu crystals in a SiO2-rich matrix, composed of glass and alpha-cristobalite phase. These glasses and glass ceramics show blue luminous properties due to the 4f(7)-4f(6)5d(1) transition of the Eu2+ ions. The blue-emission intensity of the glass ceramics containing CaAl2Si2O8:Eu significantly depended on the heat-treatment time for phase separation and crystallization. (c) 2007 The Electrochemical Society.