Intense Red-Emitting Phosphors for White Light Emitting Diodes

Abstract

Intense red phosphors, AgGd0.95Eu0.05(WO4)2−x(MoO4)x(x=0−2)AgGd0.95Eu0.05(WO4)2−x(MoO4)x(x=0−2) have been synthesized and characterized by powder X-ray diffraction (XRD) and photoluminescence. Powder XRD results reveal a phase transition from monoclinic to tetragonal structure at x⩾0.5x⩾0.5 . All compositions with Eu3+Eu3+ show red emission on excitation either in the charge-transfer band or Eu3+Eu3+ levels. Intense red emission is obtained in the molybdates, AgGd0.95Eu0.05(MoO4)2AgGd0.95Eu0.05(MoO4)2 under 465-nm excitation. Studies on AgGd1−yEuy(WO4)2AgGd1−yEuy(WO4)2 and AgGd1−yEuy(MoO4)2AgGd1−yEuy(MoO4)2 ( y=0.1−1y=0.1−1 in steps of 0.1) show that the emission intensity is maximum for compositions with y=0.2y=0.2 and 0.3, respectively, and a decrease in emission intensity is observed for higher yy values. The intense red emission of the tungstate and molybdate phosphors under 394 and 465 nm excitation, respectively, suggests that these materials are promising candidates as red-emitting phosphors for near-UV/blue GaN-based light-emitting diodes for white light generation.