Preparation And Luminescent Properties Of Mo³⁺/Ce³⁺ Doped NaREF₄ Nanoparticles

Rare-earth ions have been widely applied to up-conversion luminescent materials because of their unique luminescent properties that originated from 4f electron configuration,which include sharp luminescence band,low luminescence backgrounds,etc.Rare earth doped up-conversion nano luminescent materials?UCNPs?are widely applied on biological detection,cell imaging,anti-counterfeiting,solar cells.Therefore,the optimization of preparation method,the functional design and the material structure design of rare earth doped up-conversion nano luminescent materials are hot issues in luminescence domains.In current dissertation,the low phonon energy NaREF₄ is selected as the research object,and line of fluorescence regulation is investigated and used ion co-doped technology to achieve the UCNPs fluorescence intensity and fluorescence color,and the luminescence mechanism of the system research.The main work is summarized as follow:?1?NaGdF₄:20%molYb³⁺/2%molEr³⁺ up-conversion luminescent nanomaterials were prepared by solvothermal method,and the synthesis process of the up-conversion nanomaterials under the optimum synthesis conditions was fully understood and mastered.At the same time,Mo³⁺/Yb³⁺/Er³⁺ doped ?-NaGdF₄ nanocrystals with different Mo³⁺ concentrations are synthesized,and the luminescence properties of the UCNPs have been studied under 980nm excitation for the sensitive biological applications.A possible mechanism for this behavior is proposed in this report.It was found that the up-conversion luminescence intensity of the green emissions of the up-conversion NPs co-doped with 10%Mo³⁺ ions was enhanced 9 fold and that the red emission was enhanced 4 fold.The experimental results suggest that the enhanced UC luminescence from the Mo³⁺ doped ?-NaGdF₄:20%molYb³⁺/2%molEr³⁺ nanocrystals may have potential practical biological applications.?2?The UC luminescence properties of Yb³⁺/Ho³⁺ co-doped NaLuF₄ nanocrystals were systematically investigated under NIR 980nm excitation.The UC emission tuning from green to red in NaLuF₄:20%molYb³⁺/2%molHo³⁺ nanocrystals were successfully achieved by co-doping Ce³⁺.It is concluded that two efficient cross relaxation processes of 5S2/5F₄(Ho³⁺)+ 2F5/2(Ce³⁺)/5F5(Ho³⁺)+ 2F7/2(Ce³⁺)and 5I6(Ho³⁺)+ 2F5/2(Ce³⁺)/5I7(Ho³⁺)+ 2F7/2(Ce³⁺)between Ho³⁺ and Ce³⁺ are found to be dominant UC pathways for tuning the emission color from green to red in single NaLuF₄:20%molYb³⁺/2%molHo³⁺ nanocrystals.These UCNPs with different up-conversion color are more potentially used as the micro optoelectronic device,color display and anti-counterfeiting applications.