Growth And Packing Research With Yag:Ce,Sm,Mn Series Crystals For White Led

White light-emitting diodes (WLED) is an brand new solid state light source, which present broad prospects for development due to their unique properties including green, energy savings, environment-friendly. The white LED with low temperature and high color rendering index can prepared hardly due to the Ce:YAG phosphors lack of red light emitting component. Especially, the patent of Ce:YAG yellow phosphor technology have been monopolized by foreign limits its popularization. In order to solve these problems, it is more important to study fluorescent host material for white LED with better excellent performance.Single crystal material has a relatively high light yield including the following advantages:1. High excitation and emission efficiency;2. High uniformity;3. Stable physical and chemical performance, high thermal conductivity, long lifetime;4. Be able to realize the improvement of red component and tuning of light-emitting wave band;5. Optimize encapsulation structure for white LED. Therefore, single crystal is an ideal fluorescent material. However, the current research results indicate that the Ce:YAG single crystal still exists many disadvantages including low luminous efficiency, color coordinates deviate from the best position of white light (x=0.33, y=0.33), high color temperature, lack of effective red emission composition. Therefore, in this article, the LED luminous performance is improved by enhancing red light emission through doping Mn and Sm into the Ce:YAG single crystal, and the optical property of crystals is also studied by using X-ray powder diffraction, absorption and fluorescence spectrum, Variable temperature spectrum, electron paramagnetic resonance spectrum (EPR) and photoelectric performance. The results show as follows:1. Ce,Sm:YAG, Mn:YAG and Ce, Mn:YAG single crystal were grown using Y2O3, Al2O3, CeO2,with a purity of99.99%and Sm2O3, MnO2with a purity of99.9%as raw material, and the technological conditions of crystal growth was also optimized.2. The crystal phase structure of YAG was not affected by adding the Ce3+, Sm3+, Mn2+ions by XRD analysis, cubic structure of YAG have formed in the crystals, no other impurity phase and the grown single crystal has a good quality.3. The position and intensity of light emitting peak for Ce,Sm:YAG, Mn:YAG and Ce,Mn:YAG single crystal are studied by absorption spectrum, excitation emission spectrum. The results showed that red light emitting peak at616nm significantly enhanced with the doping concentration of Sm3+ion increased; Except the luminescence peak of Ce3+ion at530nm, the characteristics emission peak of the Mn2+ion at 566nm was also appeared in Ce, Mn:YAG single crystal, which increasing the luminescence center, expanding the full widths at half maximum, making a red shift for the emission spectrum and improving the white LED optical performance.4. The variable temperature spectrum of Ce, Sm:YAG single crystal was studied. The results showed that the Ce, Sm:YAG single crystal used for white LED has good light-emitting stability; At the same time, the main emitting peak at529nm shows a red shift with the increase of temperature.5. The influence of the annealing process on the luminescent properties of Ce, Sm:YAG was discussed. The results showed that the oxygen ions vacancy in crystals reducing, and the luminous intensity improving by the O2annealing. And it reflects good stability in terms of packaged LED.6. The characteristics spectrum of the Mn2+ion in Mn:YAG and Ce, Mn:YAG samples showed the hyperfine structure, which showed very small anisotropy in the aspect of hyperfine coupling for the Mn2+ion.7. The performance of white light of Ce, Sm:YAG single crystal with the blue chip was studied. The results showed that the photosynthetic efficiency has a significant increasing and the color rendering index decreasing with the increase of sample thickness. The photosynthetic efficiency is decreasing and the color rendering index increasing as the doping concentration of Sm3+increases. The good parameters as:the color coordinate (0.2991,0.3200), a luminous efficiency of98.837lm/W, and the color rendering index is71.1when the thickness of the sample is between0.2mm and0.25mm, with doping concentration is0.31wt%, which could satisfying the requirement for the white LED lighting. Mn doping can make it easier to stay within the white range. The parameters as:the color coordinate (0.3103,0.3271), a luminous efficiency of93.921lm/W, and the color rendering index is72.1with the test current in60mA.