Optimization Of Preparation Conditions And Properties Of Rare Earth Doped Molybdate Luminescent Materials

Rare-earth luminescent materials can be divided into up-converting luminescent materials and down-converting luminescent materials.The up-converting luminescent material can absorb two or more long-wavelength near-infrared light to emit short-wavelength visible light,has advantages of low auto-fluorescence background,high signal-to-noise ratio,and high detection sensitivity.and the near-infrared excitation wavelength is located at the biologically optical transparent window.Shows valuable potential applications in energy,biomedicine,etc.The unique conversion method of Down-conversion luminescence makes the luminous quantum efficiency more than 100%,in the field of display lighting,silicon monocry-stalline solar panels and other areas have great potential applications.In this paper,co-precipitation-hydrothermal synthesis of an Eu2+,Nd3+ doped SrMoO4 up-conversion luminescent material and a red light material with Eu3+ doped MCaMoO4(M= Li,Na,K).Optimize synthetic conditions that affect their luminescent properties,the X-ray diffraction analysis,fluorescence spectrum analysis and field emission scanning electron microscope analysis were performed on the products under the optimized conditions.Its main research content is as follows:(1)Co-precipitation-hydrothermal synthesis of SrMoO4:Eu2+,Nd3+ up-conversion luminescent materials.First,single factor optimization was performed on the preparation conditions to obtain a preliminary single factor optimization condition.On this basis,the optimal combination condition was obtained as an activator.Eu2+ion doping concentration InEu/sr=0.10,sensitizer Nd3+ ion doping concentration nNd/Eu=2.0 coprecipitation system pH=6,dispersant PEG-2000 dosage Mp/M=0.07.Three repetitions of the experiment were performed under optimal conditions,and the obtained target product was subjected to X-ray diffraction analysis,Field emission scanning electron microscope analysis and Fluorescence spectrum analysis.The XRD results showed that the structure of the target product was a single tetragonal scheelite SrMoO4 crystal structure,the doping of rare earth ions does not change the structure of the matrix material.The SEM analysis showed that the crystal particles had a square structure with a particle size of 100 nm.The results of fluorescence spectrum analysis showed that the excitation wavelength of the target product was 808 nm,corresponding to the characteristic absorption peak of Nd3+,which was attributed to 4F3?4I9/2 and the emission peak was located near 527 nm,corresponding to the characteristic emission of Eu2+,Velonging to 4f65d?4f7 characteristic emission,luminescence mechanism belongs to upconversion luminescence.(2)Co-precipitation-hydrothermal method was used to synthesize red light material of CaMoO4:Eu3+.Firstly,the single factor optimization was performed on the preparation conditions,and the preliminary single factor optimization conditions were obtained;on this basis,the orthogonal experiment optimization was performed.The optimal experimental conditions were Eu3+ ion doping nEu/Ca=0.25,co-precipitation system pH=6,co-precipitation temperature Tc=50? dispersant PEG-2000 dosage Mp/M=0.03.The experiment was repeated three times under optimal conditions and the prepared sample was subjected to X-ray diffraction analysis,Field emission scanning electron microscope analysis and Fluorescence spectroscopy analysis.XRD analysis showed that the crystal structure of the target product was a single tetragonal CaMoO4 structure.SEM analysis showed that the crystal particles were regular spherical with a particle size of 100 nm.Fluorescence analysis showed that the target product could be excited by 395nm,465nm(7F0?5L6,7F0?5D2 electron absorption transition belonging to Eu3+)to produce 595nm(5D0?7F1 magnetic dipole transition of Eu3)and the emitted light at 616 nm(5D0?7F2 electric dipole transition of Eu3+)is visually observed as red light.On this basis,the target products were doped with Li+,Na+,and K+ ions as charge compensators.The analysis results show that the crystal structure,morphology and size of the product after doping the charge compensation agent do not change significantly compared with that before the undoped product.The luminescence properties of the target product increase first and then decrease as the doping concentration of the charge compensator increases.The luminescence intensity reaches its maximum when nM/Ca=0.15,and the enhancement of the luminescence intensity is most significant with the doping of K ions.