Synthesis And Properties Of Long Afterglow Zinc Germanate

The potential applications of Zn₂GeO₄(ZGO)nanocrystals in the fields of electricity,optics and catalysis have attracted much attention due to their excellent chemical stability,excellent luminescence properties and easy band gap adjustment.Atpresent,such ZGO nanocrystals can be obtained by solid phase synthesis method,chemical vapor deposition method,co-precipitation method and electrospinning method,microwave hydrothermal method.However,microwave hydrothermal synthesis is considered to be an effective,rapid and simple method.Microwave hydrothermal synthesis can improve the size and morphology of crystals by controlling the synthesis conditions(such as saturation,temperature,solvents and precursors),increasing the chemical kinetic growth rate and forming high crystallization products.Therefore,microwave hydrothermal method has been proved to be very useful and fast to obtain ZGO nanostructures with high purity,strong crystallinity,different morphologies and sizes.In this paper,the growing Zn₂GeO₄-based nanomaterials were doped with Mn²⁺and co-doped with Mn²⁺and Yb³⁺by microwave hydrothermal method.By introducing the defect energy level,the long afterglow properties of Zn₂GeO₄based nanomaterials were improved and changed.The morphology of different reaction times and different reaction temperatures were studied.Specific research contents and results are as follows:1.The best morphology and properties of Zn₂GeO₄doped manganese long afterglow materials were obtained by microwave hydrothermal method at p H=7,temperature controlled at 160°C and reaction time of 10 minutes.PL spectroscopic characterization showed that the pure Zn₂GeO₄sample showed blue emission due to defects,and the mangane-doped Zn₂GeO₄ nanorods showed green emission under UV excitation.The possible mechanism of formation was proposed.2.We synthesized Zn_1.96-xGeO_4+1/2x:Mn0.04Yb _X phosphors by microwave hydrothermal method.Under the synergistic effect,Mn²⁺acts as a broadband spectral sensitizer to absorb UV-Vis(280nm-500nm)photons and transfer energy to Yb³⁺,resulting in attenuation of fluorescence lifetime and characteristic spectrum of green emission,indicating that Mn²⁺is effective in energy transfer to the tetrahedral matrix lattice.The fluorescence spectrum shows that Yb³⁺is a near-infrared emission source at about 1000 nm wavelength.In this paper,it is proved that the microwave hydrothermal method is an efficient and mild method for the synthesis of Zn₂GeO₄based nano-fluorescent materials,which has good long afterglow properties,and provides ideas for the synthesis and application of nano-fluorescent materials in the future.