Luminescent properties of HTP AgGd_(1-x)W_2O_8:Eu_x ~(3 +) and AgGd_(1-x)(W_(1-y)Moy)_2O_8:Eu_x ~(3 +) phosphor for white LE

摘要

ntense red phosphors, AgGd_(1-x)Eux(W_(1-y)Moy)_2O_8 (x=0.0-1.0, y=0.0-1.0), have been synthesizedthrough traditional solid-state reaction and characterized by X-ray diffraction (XRD) and photolumines?cence (PL). XRD results reveal that AgGd_(1-x)EuxW_2O_8 synthesized at 1000 1C has a tetragonal crystal structure, which is named as high temperature phase (HTP) AgGdW_2O_8. All phosphors compositions with Eu~(3 +) show red and green emission on excitation either in the charge-transfer or Eu~(3 +) levels. Analysis of the emission spectra with different Eu~(3 +) concentrations reveal that the optimum dopant concentration for Eu~(3 +) is x=0.6 in the HTP AgGd_(1-x)EuxW_2O_8 (x?0.0-1.0). Studies on the AgGd_(0.4)Eu_(0.6)(W_(1-y)Moy)_2O_8 (y?0.0-1.0) and AgGd_(1-x)Eux(W0.7Mo0.3)_2O_8 (x?0.0-1.0) show that the emission intensity is maximum for compositions with y=0.3 and x=0.5, respectively, and a decrease in emission intensity is observed for higher y or x values. The Mo6 + and Eu~(3 +) co-doped AgGd(WO_4)_2 phosphors show higher emission intensity in comparison with the singly Eu~(3 +)-doped AgGd(WO_4)_2 in UV region. The intense emission of the tungstate/molybdate phosphors under 394 and 465 nm excitations, respectively, suggests that these materials are promising candidates as red-emitting phosphors for near-UV/blue GaN-based white LED for white light generation.