Synthesis And Luminescent Mechanisms Of Blue Phosphor Based On Silicate And Fluoride

Rare earth elements play an important role in luminescent materials.Blue photoluminescence materials are widely used in luminescent material.In white LEDs,blue phosphors,one of red-green-blue?RGB?phosphors,can affect the color rendering index and improve the color temperature.In light-conversion farmfilm,it is significant to convert ultraviolet and green light which plants do not absorb into blue and red light which benefit to plants growth.In recent years,the research of green-to-red phosphors has been very mature.Therefore,there is important theoretical significance and application value to study ultraviolet-to-blue phosphors.Silicates are excellent hosts for photoluminescence materials for their low-cost and high physical-chemical stability.Natural fluorite?CaF₂?are excellent hosts for photoluminescence materials.Because their low energy of vibration can improve the conversion efficiency,furtherly reduce the influence of the phonon relaxation process and increase the cross relaxation process.In this thesis,with silicate and CaF₂ as matrix,the phase and luminescent properties of Ce³⁺activated BaZnSiO₄ and Ba₂ZnSi₂O₇phosphors were studied in detail.The BaZnSiO₄:Ce³⁺phosphor was studied in three aspects:different cerium source,doped Al³⁺ion,and solid solution matrix.And the synthesis and luminescent properties of Eu²⁺ion activated CaF₂ phosphor and Ca_1-xSr_xF₂ solid solution phosphor were examined in detail.The relationship between phase,crystal structure,and excitation and emission spectra was analyzed,and its luminescence mechanism was discussed.?1?Among the three kinds of cerium source,using CeCl₃ as cerium source favored the synthesis of pure phase BaZnSiO₄ and strengthens the luminous intensity,and 0.9%was the best doped Ce³⁺ion concentration.The phosphor exhibited a peak at 405 nm in violet-blue luminescence.For Ce₂ZnSi₂O₇:Ce³⁺phosphors,luminous intensity was the largest when using CeCl₃ as cerium source.?2?because of the doping of Al³⁺ion,BaZnSiO₄:Ce³⁺phosphor blue-violet luminescence red shifted by nearly 10 nm,and a yellow emission peak of 550 nm was observed.The emission spectra at 330 nm and 375 nm can be synthesized to white light.?3?Based on CeCl₃ as the cerium source and the best doped Ce³⁺ion concentration in chapter one,two kinds of phosphor was synthesized.One is BaZn_1-xMgxSiO₄:Ce³⁺phosphor,and the optimum solid solution ratio for Zn:Mg equals to 7:3.The other one is Ba_1-xSr_xZn_0.7Mg_0.3SiO₄:Ce³⁺phosphor was synthesized,the optimum solid solution ratio for Ba:Sr equals to 6:4.?4?Ca_1-xSr_xF₂:Eu²⁺solid solution phosphor was synthesized,and the effect of Ca/Sr ratio on the phase composition and luminescent properties of the phosphor was investigated.It was found that when Ca:Sr equals to5:5,the red shift of the main peak of the phosphor was the most obvious,reaching 440 nm.And this phosphor is a potential violet-to-blue agricultural conversion agent,and can effectively achieve the fine regulation of the spectrum.