Synthesis of La2(1-x)(MoO4)3:RE2x (RE = Eu, Tb) Phosphor Powders via a Sol-Gel Combustion Process and Their Photoluminescent Properties

Powder phosphors of La2(1-x)(MoO4)(3):RE2x , RE = Eu3+ or Tb3+, were prepared by sol-gel combustion reactions with calcination temperatures of 600-900A degrees C. Their reaction process, crystal structures, morphologies, and optical properties were characterized by differential scanning calorimetry, powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and photoluminescence spectroscopy, respectively. Our results reveal that all of these phosphors adopted the tetragonal crystal structure. The obtained La2(1-x) (MoO4)(3):Eu-2x phosphors exhibit a notable emission in the red light range which can be assigned to the D-5(0) -> F-7(2) transition of Eu3+ upon excitation at 459 nm. When the phosphors were irradiated by 277 nm light, they showed predominant green emission (D-5(4) -> F-7(5)) at 540 nm. The highest emission of the phosphors can be achieved by adjusting the doping concentration of Eu3+ at x =0.25 or Tb3+ at x =0.09.