Single-phase white-emitting and tunable color phosphor Na_(3)Sc_(2)(PO_(4))_(3):Eu^(2+),Dy^(3+): Synthesis, luminescence and energy transfer

A series of Eu^(2+)/Dy^(3+) single doped and co-doped Na_(3)Sc_(2)(PO_(4))_(3) phosphors were synthesized by the high-temperature solid-state method,and their phase,morphology,and luminescence properties were characterized.Under the excitation of 370 nm,the Na_(3)Sc_(2)(PO_(4))_(3):Eu^(2+),Dy^(3+) phosphor can emit white light whose spectrum is composed of a broad emission band centered at 460 nm and the other three peaks at 483,577,and 672 nm,respectively.There is energy transfer from Eu^(2+)to Dy^(3+)ion in Na_(3)Sc_(2)(PO_(4))_(3):Eu^(2+),Dy^(3+) phosphor due to the good overlap between the emission spectrum of Na_(3)Sc_(2)(PO_(4))_(3):Eu^(2+) and the excitation spectrum of Na_(3)Sc_(2)(PO_(4))_(3):Dy^(3+),which is further confirmed by the fluorescence lifetime decrease of Eu^(2+)ion with the increase of Dy^(3+) concentration.The process of energy transfer is via dipole–quadruple interaction which is confirmed by applying Dexter's theory.By increasing the Dy^(3+)concentration,the color coordinates of the Na_(3)Sc_(2)(PO_(4))_(3):0.01Eu^(2+),xDy^(3+)phosphors can be adjusted from blue to white,and then to yellow.The optimized concentration of Dy^(3+)ions is 4.0 mol%,beyond which the concentration quenching will take place.The Na_(3)Sc_(2)(PO_(4))_(3):Eu^(2+),Dy^(3+)phosphor shows fairly good resistance to thermal quenching behavior,of which the emission intensity at 423 K can maintain 90.3%of the initial value(298 K).These results suggest that the Na_(3)Sc_(2)(PO_(4))_(3):0.01Eu^(2+),xDy^(3+)phosphors have potential applications as the color-tunable or a single-phase white emitting phosphor in white LEDs.

Eu^(3+)-doped BaLiZn_(3)(BO_(3))_(3):A novel red-emitting phosphor for blue chips excited white LEDs

A series of novel red-emitting BaLiZn_(3)(BO_(3))_(3):Eu^(3+)phosphors were synthesized through the high temperature solid state reaction method.The phase composition,crystal structure,morphology and photo luminescence property of the BaLiZn_(3)(BO_(3))_(3):Eu^(3+)samples were systematically investigated.The phosphor can be efficiently excited by the near ultraviolet light(NUV)of 396 nm and blue light of 466 nm,and give out red light emission at 618 nm corresponding to the electric dipole transition(^(5)D_(0)→^(7)E_(2)).The optimal doping concentration of Eu^(3+)ions in BaLiZn_(3)(BO_(3))_(3)is determined to be about 3 mol%,and the concentration-quenching phenomenon arise from the electric dipole-dipole interaction.The temperature dependent luminescence behavior of BaLiZn_(3)(BO_(3))_(3):0.03 Eu^(3+)phosphor exhibits its good thermal stability,and the activation energy for thermal quenching characteristics is calculated to be 0.1844 eV.The decay lifetime of the BaLiZn_(3)(BO_(3))_(3):0.03 Eu^(3+)is measured to be 1.88 ms.These results suggest that the BaLiZn_(3)(BO_(3))_(3):Eu^(3+)phosphors have the potential application as a red component in white light emitting diodes(WLEDs)with NUV or blue chips.