Preparation, structure and photoluminescence properties of EU2+ and Ce3+-doped SrYSi4N7

Undoped and Eu2+ or Ce3+-doped SrYSi4N7 were synthesized by solid-state reaction method at 1400-1660 degreesC under nitrogen/hydrogen atmosphere. The crystal structure was refined from the X-ray powder diffraction data by the Rietveld method. SrYSi4N7 and EuYSi4N7, being isotypic with the family of compounds MYbSi4N7 (M=Sr, Eu, Ba) and BaySi(4)N(7), crystallize with the hexagonal symmetry: space group P6(3)mc (No. 186), Z = 2, a = 6.0160 (1) Angstrom, c = 9.7894 (1) Angstrom, V = 306.83(3) Angstrom(3); and a = 6.0123 (1) Angstrom, c = 9.7869 (1) Angstrom, V= 306.37(1) Angstrom(3), respectively. Photoluminescence properties have been studied for Sr1-xEuxYSi4N7 (x=0-1) and SrY1-xCexSi4N7 (x = 0-0.03) at room temperature. Eu2+-doped SrYSi4N7 shows a broad yellow emission band peaking around 548-570 nm, while Ce3+-doped SrYSi4N7 exhibits a blue emission band with a maximum at about 450 nm. SrYSi4N7:Eu2+ can be very well excited by 390 nm radiation, which makes this material attractive as conversion phosphor for LED lighting applications. (C) 2004 Elsevier Inc. All rights reserved.