Synthesis And Application Of Two Materials Based On Lanthanide Rare Earth Elements Dy And Sm

Looking forward to the global rare earth resources,although China has always been in a far leading position,but the current research status shows that China for rare earth resources development late,late research,mostly rely on exports and rough processing.Therefore,the research and development of rare earth functional materials become extremely urgent.The tetragonal molybdate can form effective absorption in a certain range,and then transmit to luminescent ions,and then produce many luminescent light sources such as fluorescent powder,fluorescent rod,and fluorescent lamp that are nowadays visible everywhere.Rare earth element doped phosphors are essential components in the field of illumination at present.Usually we use UV chip to excite fluorescent agents to prepare light-emitting diodes（LEDs）,which have better luminescent properties of third-generation incandescent lamps.In addition,we hope that rare earth elements will be applied in more fields and form more functional materials.This work is devoted to exploring the application of new rare earth element doped materials in different fields.Taking full advantage of the unique luminescence properties of rare earth ions,the outstanding porosity and specific surface advantages of Ln-MOFs and electrochemical techniques,two new Dy/Sm doped materials were successfully prepared and applied.Specific contents are as follows:1.Dy and Sm ions were doped into Na Y（Mo O₄）₂matrix to form inorganic luminescent materials that can realize cold and warm white LED.With Na Y（Mo O₄）₂as the substrate and Dy/Sm as the luminescence center,the synthesized inorganic luminescence materials were coated on UV-LED chips to prepare white LED with good luminescence properties.XRD and SEM scans showed that the material was small spherical particles,and the crystal form was consistent with the standard Na Y（Mo O₄）₂.The fluorescence spectrum analysis shows that under the excitation of400 nm near-ultraviolet light,Na Y（Mo O₄）₂:Dy³⁺,Sm³⁺materials show 482 nm blue light and 570 nm green-yellow light corresponding to the characteristic transitions of⁴F_9/2→⁶H_15/2and ⁴F_9/2→⁶H_13/2of Dy³⁺,while yellow light at 600 nm and red light at646 nm,on the other hand,correspond to characteristic transitions of ⁴G_5/2→⁶H_7/2and⁴G_5/2→⁶H_9/2for Sm³⁺.Under the excitation of near ultraviolet light,the superposition of three colors can form a good white light emission.According to Dexter’s theory of energy transfer method,it is calculated that the mechanism of energy transfer is galvanic dipole-galvanic dipole interaction.The white light LED device can realize warm white light emission（3705 K）alone,and greatly reduce the cost under the premise of reducing the harm of blue light to the human eye.It suggests that this material is an excellent single substrate white phosphor material that can be applied to near-UV excited white LEDs.2.A phosphomolybdic acid-modified electrochemical sensor was constructed to detect H₂PO₄^-using Dy/Sm-MOFs material.A phosphomolybdic acid/（Dy/Sm-MOFs）sensor with high porosity and large specific surface area was prepared as the substrate of phosphomolybdic acid modified electrode for the detection of H₂PO₄^-.The results of performance evaluation showed that the electrochemical sensor had a linear relationship between 0.01-0.17 m M H₂PO₄^-and a detection limit of 0.005 m M.It had the advantages of strong anti-interference and good stability,opening a new way for the detection of orthophosphoric acid dihydrogen.