Synthesis and luminescence properties of glass ceramics containing MSiO3:Eu2+ (M=Ca, Sr, Ba) phosphors for white LED

Eu2+ doped silicate glasses were prepared of the system 52SiO(2)-48MO: xEu(2+) (in molar ratio, M=Ca, Sr, Ba; x=1, 3, 5, 7, 9) by a high temperature melt-quenching method in a reducing atmosphere. Glass ceramics containing MSiO3:Eu2+ (M=Ca, Sr, Ba) nano-phosphors were obtained after the heat treatment of the glass samples. The excitation, emission spectra and lifetime decay curves of 4f(6)5d(1)-> 4f(7) of Eu2+ were measured and interpreted with respect to their crystal structures and multi-site occupations of divalent europium in the hosts. Their excitation bands mainly extend from 450 to 250 nm, which is adaptable to the main emission region of the UV LED chip. With UV light excitation, the Eu2+ emission in CaSiO3, SrSiO3 and BaSiO3 shows blue, green and yellow colors centered at 440, 505 and 555 nm, respectively. The critical Eu2+ concentration was studied and determined to be x=5 for both CaSiO3 and SrSiO3 and x=7 for BaSiO3 phosphors. The results show that the Eu2+ doped glass ceramic phosphors containing MSiO3 (M=Ca, Sr, Ba) nano-crystals can be used as potential matrix materials for a high power white LED pumped by the UV LED chip. (C) 2011 Elsevier B.V. All rights reserved.