Energy Transfer And Luminescent Properties Of Tervalence Rare-earth Ions-activated Ca_0.5Sr_0.5MoO₄ And BaLa₂ZnO₅ Phosphors

In this paper, a series of Ca0.5Sr0.5MoO4:Sm3+, Ca0.5Sr0.5MoO4:Dy3+, BaLa2ZnO5:Eu3+/Bi3+ phosphors were synthesized by solid state reaction, in which Ca0.5Sr0.5MoO4 and BaLa2ZnO5 played the roles as hosts. The microstructure or macrostructure, X-ray diffraction,energy transfer, fluorescent properties, chromaticity coordinates were analyzed and studied.(1) Ca0.5Sr0.5MoO4:Sm3+phosphor was synthesized, and its microstructure, energy transfer and fluorescent properties were characterized. Besides the lattice constant,Ca0.5Sr0.5MoO4, CaMoO4 and SrMoO4 have similar crystal structure. When excited the charge transfer band, the host will absorb energy and transfer the energy to the doped ions, and then the characteristic emission of Sm3+ions will be realized. Through doping the charge compensator and increasing the concentration of Sm3+ ions, the emission intensity of Ca0.5Sr0.5MoO4:Sm3+phosphors could be enhanced. The concentration quenching happens when the concentration of Sm3+ is 6%. Analysis shows that the concentration quenching mechanism is the energy transition among the nearest neighbor ions.(2) Ca0.5Sr0.5MoO4:Dy3+phosphor was synthesized, and its macrostructure, energy transfer and fluorescent properties were characterized. The SEM images of different Dy3+concentration doped Ca0.5Sr0.5MoO4:Dy3+phosphors indicate that the doping of Dy3+will lead to an inhibition of grain growth. When excited the charge transfer band, the host will absorb energy and transfer the energy to the doped ions, and then the characteristic emission of Dy3+ ions will be realized. The chromaticity coordinates changed from blue-green to yellow area depending on the Dy3+concentration, because of the energy transfer from host to Dy3+. In addition, the main mechanism of the concentration quenching was the electric multiple interaction between Dy3+ions.(3) Bi3+/Eu3+ doped Ba La2ZnO5 phosphor was synthesized, and its macrostructure, energy transfer and fluorescent properties were characterized. BaLa2ZnO5 crystallized in a tetragonal structure, and their basic structure consists of LaO8, BaO10 and ZnO4 polyhedra. Bi3+in Ba La2ZnO5 emits blue light and Eu3+emits red light. In BaLa1.99-yZnO5:0.01Bi3+, yEu3+samples, the decay time of Bi3+emission decreases with the increasing of Eu3+ concentration, indicating the energy transfer from Bi3+ to Eu3+exists. The energy transfer has been demonstrated to be a resonant type through adipole-dipole interaction mechanism. In BaLa1.99-yZnO5:0.01Bi3+, yEu3+ samples, the color hue change from blue to red by adjusting the amount of Eu3+ ions. The co-doping of small amount of Bi3+into Eu3+doped Ba La2ZnO5 can realize brighter red light attributed to energy transfer from Bi3+ to Eu3+, but this co-doping of Bi3+ does not induce obvious changes in CIE chromaticity coordinates.