Synthesis And Properties Of Rare Earth Molybdates Luminescent Materials With Diverse Morphologies Structures

In recent years,micro-nano rare earth luminescent materials have attracted more attention.Compared with other matrix materials,the micro/nano rare earth luminescent materials not only have a particle size of micro-nanoscale dimension,but also exhibit stable chemical and physical properties,narrow spectral lines,bright colors,and high color purity.The rare earth ions have strong absorption capacity and small spontaneous transition probability.Moreover,they can emit light from ultraviolet to near-infrared and has a wide range of applications in aerospace,medical,display,lighting,and detection.Furthermore,among different synthetic methods,hydrothermal/solvothermal synthesis has significant advantages,such as low raw material cost,high product yield,relatively uniform phase,good crystallinity,relatively low energy consumption,wide application range,less pollution to the environment,etc.Therefore,the research work of this paper adopted hydrothermal/solvent thermal synthesis method to prepare a series of rod-shaped rare earth molybdate luminescent nano/micromaterials with uniform size and good crystallinity.In addition,the hollow spherical rare earth luminescent molybdate nanomaterials were synthesized by hydrothermal method through sacrificial template approach,and the morphology,structure,and phase of the materials were studied in detail.The 3-aminophenol-formaldehyde resin（APF）microspheres with uniform particle size and good dispersion were successfully prepared by hydrothermal method.Next,with APF as a template and urea as a precipitant,a layer of Gd（OH）CO₃ is uniformly coated on the APF spheres to form a precursor.Then,the obtained precursor is converted into APF@NaGd（MoO₄）₂ with uniform size and good crystallinity by a hydrothermal process.Finally,the template was removed by calcination to obtain NaGd（MoO₄）₂ hollow spheres.The morphology,phase,and composition of NaGd（MoO₄）₂ hollow spheres were studied in detail.Moreover,the rare earth ions doped NaGd（MoO₄）₂:Tb³⁺,NaGd（MoO₄）₂:Eu³⁺,NaGd（MoO₄）₂:Yb³⁺/Er³⁺,and NaGd（MoO₄）₂:Yb³⁺/Ho³⁺samples were prepared by the same experimental method,and the luminescence properties of the sample were explored.The rod-shaped NaLa（MoO₄）₂ with uniform size and good dispersion was synthesized by hydrothermal reaction with Na₂MoO₄ and La（NO₃）₃ and sodium citrate as raw materials（pH 4）.The effect of pH value,hydrothermal temperature and time,the amount of sodium citrate additive on the morphologies of the samples were investigated in detail.The emission spectra,fluorescence lifetime,and optimum doping concentration of Tb³⁺ions in NaLa（MoO₄）₂ host were also studied.The NaBi（MoO₄）₂ material with rod-like structure was synthesized by a solvothermal method with the mixing solution of glycerol,ethanol,and water as solvent.Finally,the obtained samples were calcined in air.Moreover,the morphology,phase and composition of the samples were studied after solvothermal and different calcination temperatures.Furthermore,rare earth ions Er³⁺,Yb³⁺/Er³⁺,Yb³⁺/Ho³⁺,and Yb³⁺/Tm³⁺ions were doped into NaBi（MoO₄）₂ host.The luminescence properties of the as-obtained phosphors prepared at different reaction conditions were investigated in detail.