| Along with the start of the fourth lighting revolution, LED becomes a leader in the industry. The other industries which related to the LED developed rapidly. The phosphor is one of the important components of LED. The silicate phosphor, especially M2SiO4: Eu2 +(M = Sr, Ba, Ca), has attracted the attention of most researchers in numerous kinds of phosphors, because it has good chemical stability, high luminous efficiency, high color rendering and color reducibility, and lower color temperature. Luminous performance is one of the main parameters of LED, and the thermal stability of silicates phosphors is relatively low, so it is the main direction of research to improve the silicate phosphor luminescence properties and thermal stability.The green-yellow emitting phosphors and new phosphors of nitrogen oxides(Sr1-zBaz)2-yEuySiO4-6xN4x(0 ≤ z ≤ 1, 0.01 ≤ y≤ 0.11, 0 ≤ x ≤ 0.33) were synthesized through the high temperature solid-state reaction technique in this thesis, H2 as reducing atmosphere and N2 as protective atmosphere in the tube furnace, and measuremented by X-ray diffraction(XRD), fluorescence spectrophotometer, and scanning electron microscope(SEM) to characterize the samples of mance, thermal stability and micro crystal structure, etc.The Sr2SiO4: Eu2+ was synthesized in different calcinations temperature. Through the test and analysis to get the optimum synthesis conditions for calcination temperature 1400 ℃, holding time 4 h, the best concentration of Eu2+ ion is that y equals to 0.05. The concentration quenching phenomenon appeared on y=0.05. With the increase of the Eu2+ ion concentration, the emission shites to red light area.(Sr1-zBaz)2-yEuySiO4 phosphors were synthesized doping Ba2+ ions. With the increasing concentration of Ba2+ ions, the X-ray diffraction peak moved to the small angle. The excitation spectrum results that excitation peak is unimodal and wide spectrum, and that the relative intensity of excitation is higher and the concentration of Ba2+ ions more. The emission spectrum results that near ultraviolet excitation is higher luminous efficiency than bule light excitation the phosphors, and that the emission site shites to blue light area. When z equal to 0.5, the relative luminous intensity of fluorescent powder was optimized, thermal stability is improved obviously. Optimization of cosolvent NH4 Cl quality percentage is F = 2%, calcination temperature is 1300 ℃.The thermal stability and luminescence performance of(Sr0.5Ba0.5)2-yEuySiO4-6xN4 x phosphors have improved when doping N3- ions in the crystal. X-ray diffraction showed that the crystal structure did not change doping N3-ions. The scanning electron microscopy(SEM) shows when doped N3- ions the crystal morphology was well improved.When x equals to 0.24, the luminescence properties of phosohor was improved, the crystallization becomes better, and the thermal stability has enhanced significantly. When y equals to 0.05, the relative intensity of emission and excitation was optimized. Sr2SiO4: Eu2+ phosphors are more suitable for near ultraviolet excitation doping Ba2+ ions and N3- ions.Because orthosilicate Sr2SiO4: Eu2+ phosphors have high color rendering, lower color temperature, and high thermal stability doping Ba2+ ions and N3- ions, this phosphor can use in liquid crystal display, becklight, medical and other applications more space. |
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