Preparation Of SrO-Gd₂O₃-TiO₂-SiO₂: Eu³⁺, Bi³⁺ Red Phosphors For White LED

With breakthroughs of semiconductor light emitting diode (LED) technology, white LED has achieved attention because of many advantages such as high efficiency, energy-thrift, environment-friendly, long longevity, easy maintenance, high reliability and so forth. Currently the dominative approach to obtain the white light is to use the blue LED chips to excite yellow phosphors. However, there are many weaknesses because of lack of red color. The hot research to obtain the white light is to use the UV LED chips to excite RGB phosphors. But there are many disadvantages with red phosphors, for example, comparatively low intensity of light emission, high lumen decay and producing costs, etc. In the presence of the above issues, we attempt to find excellent performance and stable red phosphors.SrO-Gd2O3-TiO2-SiO2 red phosphor was prepared by the sol-gel method and prepared by the microwave method. First, through a series of single factor experiments, we found the important factors that significantly influence the luminous performance of the phosphor and ensured the range of each single factor. Then we carried out an orthogonal experiment and rearranged the optimal level. The main contents of the thesis include:â‘ The effect of organic solvents, stabilizer, the acidic conditions on the preparation of sols and gels was studied, the consequence showed that ethanol as solvents and diluted acetic acid as stabilizer could be advantageous to the preparation process. It concluded a good way to prepare the precursor in the preparation of the red phosphor.â‘¡The influences of reaction condition including sinter temperature, sinter time, diluted nitric acid consumption, the dosage of Eu³⁺ and Gd³⁺ as one of factors effect on the luminous properties of the phosphor were studied. The fluorescence spectral data of the phosphors showed that the three primary red phosphors meet the requirements of white LED; X-ray diffraction showed that the structure of the phosphors is Sr3Ti2O7, Sr₂TiO₄, Si₂SiO₄ etc; and SEM showed that the phosphors have a certain extent of reunion, and uneven particles.â‘¢SrO-Gd₂O₃-TiO₂-SiO₂ red phosphors was prepared by the microwave method, The influences of reaction condition including sinter time, the dosage of Fe₂O₃ on the luminous properties of the phosphor were studied. The fluorescence spectral data of microwave synthesis phosphors were almost the same as the furnace heating one's, but the intensity has decreased; X-ray diffraction showed that the structure of the phosphors is Sr(NO₃)₂; and SEM showed that the phosphors have serious reunion, and uneven particles.