Synthesis And Photoluminescence Of SrSi₂O₂N₂:Eu²⁺ Green Phosphors And M₃B₂O₆:Eu²⁺ Yellow Phosphors For LED Lighting

Compared with the traditional incandescent lamp, fluorescent lamp and halogen tungsten lamp, LED with low energy consumption, high efficiency, less thermal radiation, friendly to the environment and other significant advantages, has been widely used in office and home lighting, outdoor large screen display, LCD TV and smartphone back light, traffic lights, etc. In order to explore the method of using different synthesis is suitable for the blue and near ultraviolet wavelength of LED chips stimulate the fluorescent material, we synthesized two kinds of fluorescent material and X-ray diffraction, scanning electron microscope and fluorescence spectrometer device had been used to characterize the structure, morphology and luminescence properties of the fluorescent material. The main results are as follows: (1) In this paper, we synthesized SrSi2O2N2:Eu2+ green phosphor by using oxalic acid salt as precipitation agent. By controlling the reaction conditions (temperature, PH, etc.) and optimizing the synthesis process, the PH, morphology, particle size, luminous intensity, chromaticity and thermal stability was studied. The research results show that as the pH value increases from 2 to 5, luminous intensity increases gradually, then falls suddenly when pH value of 6.5, when the pH value is 2, there is a strong phase for Sr2Si5N8 peak, as a result of Eu2+4f65d-4f7 energy transfer. Under ultraviolet excitation, the fluorescent shows a strong green emission. We obtained the figure after precipitation, precursor structure is mainly composed of SrC2O4 coating on the surface of SisN4 massive particles, the results of scanning electron microscopy (SEM) show that many small particles closely embed on the surface of the silicon nitride particles, the conclusion can also got from XRD analysis. After 2h under 700℃ calcination, phosphors are mainly composed of SrCO3 and Si3N4. When reducing under N2 and H2 atmosphere and 1400℃ calcination after 4 hours, compared with the standard SrSi2O2N2(No.49-0840)and Sr2Si5N8 (No.85-0101) JCPD card, most of the diffraction peaks are consistent with SrSi2O2N2 standard peak. (2) By using the method of solid reaction process and SrCO3 (CaO, BaCO3, MgO), Eu2O3, H3BO3, etc as the raw materials, series of Eu2+ activated alkaline earth boric acid fluorescent material M3B2O6:Eu2+, which M= Sr, Ba, Ca, Mg was synthesized under the H2 and N2 atmosphere. To improve the luminescence efficiency of phosphor, Eu2+ concentration and synthetic temperature are optimized. Based on the replace of Sr by Ba, Ca and Mg of phosphor, matrix M3B2O6 composition is optimized. To reveal the phosphor luminescence mechanism, a diffuse reflection spectroscopy of Ca2+ replace Sr2+, for example, was made. Studies show that Sr3B2O6:Eu2+ is a very good substrate suitable for lighting, the best temperature is 1350 ℃, the best concentration of Eu2+ replace Sr2+ is 6% M, Ba, Ca and Mg doped all cause the luminous efficiency lower.