Studies On Syntheses And Fluorescence Properties Of Sm³⁺, Eu³⁺, Tb³⁺, Dy³⁺/-Li⁺ Doped Nano-ce O₂

Rare earth ion doped-nano oxides have unique luminescence property, which have extensive applications in fluorescence tags, tracking biological drugs, displaying, etc, so it is the top priority to search the synthetic method of simply operate and low cost. Based on glycine as fuel, there is a oxidation-reduction reaction between glycine and highly pure rare earth nitrate(M(NO3)3·6H2O, M = Ce, Eu, Tb, Dy, Sm), distilled water as solvent, adjusting p H value of mixed solution to 4.0, rare earth ion doped/codoped-nanometer oxide powders have been synthesized by the low temperature combustion method in the muffle furnace in the thesis, including different concentration of rare earth ions single doped-nanometer oxide powders Ce O2 : Eu3+, Ce O2 : Tb3+, Ce O2 : Dy3+, Ce O2 : Sm3+ and Li+ and rare earth ions codoped-nanometer oxide powders Ce O2 : Eu3+-Li+, Ce O2 : Tb3+-Li+, Ce O2 : Dy3+-Li+, Ce O2 : Sm3+-Li+. All of samples are foamy. The reunion phenomenon was reduced by ultrasonic processing in isopropyl alcohol. Finally, samples with good dispersion were prepared.Crystal structure, grain size of samples were characterized by X-ray diffraction(X-ray Diffractometer D/Max-2400, Rigaku). XRD shows that peak position and peak strength of samples are consistent with NO.34-0394 in PDF2-2004 standard cards by phase retrieval and comparing with PDF standard cards in the MDI Jade 5.0. Powder samples are all the face-centered cubic, the space group is Fm-3m, [225]. It is no effect on the crystal type of ceria doped with a small amount of rare earth ions. The average diameter of sample is about 12-17 nm. Particles have narrow grain size distribution and uniform distribution. Sharp diffraction peak of samples illustrated that has good crystallinity. The surface morphology of samples were characterized by scanning electron microscopy(thermal field emission scanning electron microscopy ULTRA plus, German Zeiss), SEM shows that samples have three-dimensional structure, presenting porous sponge, and holes have different size, because it has gas overflow in the oxidation-reduction reaction in the muffle furnace. Structure and grain size of samples were characterized by high-resolution transmission electron microscopy(thermal field emission transmission electron microscopy, Tecnai G2 F20, American FEI), HRTEM shows that the lattice fringe is clear, and the crystallinity is good, grain size is consistent with the XRD. The relationships between fluorescence properties of samples with doping ion type and concentration were characterized by fluorescence spectrophotometer(Luminescence Spectrometer LS55, Perkin Elmer). Every sample has the obvious characteristic peak of launch location, has fluorescence. Ce O2 : Eu3+, Ce O2 : Tb3+, Ce O2 : Dy3+, Ce O2 : Sm3+ have luminescence of orange light(599 nm, 5D0→7F1), green light(570 nm, 5D4→7F4), blue light(483 nm, 4F9/2→6H15/2), orange-red light(590 nm, 4G5/2→6H5/2 and 737 nm, 4G5/2→6H11/2), respectively. It is expected to be in the fluorescent screen and display lamp, fluorescent lamps, luminous glass, field emission display has applicative value.Even though the synthesis method is simple, and has advantages of low energy consumption and low cost, nitric oxide and carbon dioxide of the reaction process have pollution to the environment, so it needs to be improved.