Journal of the American Ceramic Society, Vol.93, No.12, 4081-4086, 2010
Crystal Structure and Photoluminescence Properties of Red-Emitting Ca9La1-x(VO4)(7):xEu3+Phosphors for White Light-Emitting Diodes
This paper reports the crystal structure and photoluminescence properties of Ca9La1-x(VO4)(7):xEu3+ (x=0-1) phosphors synthesized at various temperatures (850 degrees-1350 degrees C) in air for 12 h using traditional solid-state reaction method. Rietveld refinement of powder X-ray diffraction pattern of Ca9Eu(VO4)(7) indicated that the structure of Ca9Eu(VO4)(7) consisted of [VO4] tetrahedra and Ca/Eu atoms were filled in the space between the tetrahedral groups, with a random distribution for Eu3+ ions on four individual Ca crystallographic sites. A major intense sharp emission line, locating at 613 nm under 465 nm excitation, was observed due to the 5D(0)-7F(2) transition of Eu3+ within 4f configurations, which originates from the lower site symmetry in Ca9La1-x(VO4)(7):xEu3+. Interestingly, no concentration quenching was found in this phosphor, and thermal quenching was nearly not affected by Eu3+ concentration. The experimental results suggested that this novel red-emitting phosphor could be applied in white light-emitting diodes.