Study On The Synthesis Of Molybdate Compound By Liquid Phase And Its Photoluminescence Performance

Molybdate micro-nano material is an important branch of inorganic materials. And it has an extremely wide range of application owing to its good properties in the optical, electrical, magnetic, catalytic, etc.. In recent years, scientists have made great efforts for the synthesis of different morphologies and sizes. How to synthesize different molybdate micro- nano materials, and explore the structure and properties of micro molybdate nanomaterials has become an issue of concern, it is also a hot of scientific community today. This paper aims to study the synthesis of molybdate micro-nano materials, and to study their characterization and properties. Synthesis of micro and nano materials by liquid phase has become the most common means, the main advantages of the liquid phase synthesis of crystal morphology rules are able to synthesize controllable sizes and micro-nano materials.The main contents of this paper are summarized as follows:(1) A method for preparation of La2(MoO4)3 micromaterial with different morphologies by microemulsion reaction of sodium molybdate(Na2MoO4·2H2O) and lanthanum nitrate(La(NO3)3·6H2O) under the help of micro emulsion system was introduced in this article. It is showed that structure of La2(MoO4)3 gradually transformed from oval shape to close spherical shape when the concentration of the surfactant of CTAB changed from 0.2M to 0.4M. In addition, It can be found that a red light of a wavelength of 617 nm was emitted due to the forced electric dipole transition of 5D0â†'7F2 which inspired by a wavelength of 396 nm light in the ultraviolet region after La2(MoO4)3:Eu3+ material, calcining at 800℃ for 4h, and the best result of photoluminescence properties was obtained as the quencher concentration of the doped Eu3+ was up to about 20%mol.(2) How to selectively synthesize cerium molybdate by microwave method with different pH value was reported in this article. The results showed that the Ce2(MoO4)3·4.5H2 O was produced under the acidic condition. As the pH value was up to alkaline condition, the product was changing to be Na0.5Ce0.5MoO4. A further discussion through the DSC and TG curves showed that the Ce2(MoO4)3·4.5H2 O had a endothermic peak at about 150℃, meaning that the Ce2(MoO4)3·4.5H2 O would remove the water of crystallization when it was calcined at this temperaure. The result indicated that both of the Ce2(MoO4)3·4.5H2 O and Na0.5Ce0.5MoO4 had showed a strong absorption in the ultraviolet region near the visible light region(about 240 nm to 500nm) through the solid UV spectrum. And the energy of the band-gap of Ce2(MoO4)3·4.5H2 O was 2.12 eV, Na0.5Ce0.5MoO4 was 2.19 eV.(3) Manganese molybdates MnMoO4·xH2O(x=0.9,1.5) could be obtained by the method of a microemulsion based on a quaternary system(CTAB/ water / pentane / isoamyl alcohol) under different manganese precursors. According to XRD, the DSC and TG traces, it was proved that MnMoO4·0.9H2 O could be prepared under the precursor manganese of MnCl2·4H2O, and the other precursor manganese of C4H6MnO4·4H2O was MnMoO4·1.5H2 O. And it was showed that ω([CTAB]/[H2O]) and the different manganese precursors had great influence of the microstructure of the final product. It could be well known from the solid ultraviolet spectra that the band-gap energy of MnMoO4·0.9H2 O could reach up to 3.08 eV, and MnMoO4·1.5H2 O was 3.04 eV. It would emit a beam of red light due to the electric dipole transitions of Eu3+ 5D0â†'7F2 when MnMoO4:Eu phosphor is excited with a bunch of near ultraviolet light with a wavelength of 396 nm. And it will emit a beam of green light due to the electric dipole transitions of Tb3+ 5D4â†'7F5 when MnMoO4:Tb phosphor is excited with a bunch of near ultraviolet light with a wavelength of 274 nm.(4) Synthesis of molybdenum yttrium by hydrothermal method and It is indicated that the final product has an influence on the p H of the reaction system and surfactant PVP. The experimental results show that the final product is NaY(MoO4)2 when pH of the reaction system is between 3.00 and 10.00. It will emit a beam of red light due to the electric dipole transitions of Eu3+ 5D0â†'7F2 when NaY(MoO4)2:Eu phosphor is excited with a bunch of near ultraviolet light with a wavelength of 396 nm. Luminous intensity is related to doping concentration in a certain extent. The experiment shows that the photoluminescence capacity will achieve the best when the doping concentration of Eu3+ is 15%.