Studies On Synthesis And Photoluminescence Properties Of LED Backlight Fluoride Red Phosphor And Plant Lighting LED Far Red Fluorescent Powder

Concerning the application of the LED display backlight,this dissertation firstly optimizes the components and the synthetic process parameters of?K,Na?₂?Si,Ti?F₆:Mn⁴⁺red phosphor,and then develops a new synthetic route of K₃AlF₆:Mn⁴⁺.Finally,a new far red fluorescent material K₃AlF₆:Cr³⁺,which satisfies the application of plant light control,is developed to meet the application of plant lighting LED.The main contents of the dissertation are as follows:?1??K,Na?₂?Si,Ti?F₆:Mn⁴⁺red phosphor was successfully synthesized by ion exchange method.And the Mn⁴⁺ion concentration,solid-liquid ratio and ion exchange time were optimized by orthogonal design.The results indicate that the optimum Mn⁴⁺concentration of K₂SiF₆:Mn⁴⁺red phosphor is 0.03,the optimum solvent and solute molar ratio is 1:3,and the best ion exchange time is 45 min.As to the K₂TiF₆:Mn⁴⁺red phosphor,the optimum Mn⁴⁺concentration of is 0.09,the optimum solvent and the solute molar ratio are 1:4,and the best ion exchange time is 30 min.For the Na₂SiF₆:Mn⁴⁺red phosphor powder,it was observed that the best Mn⁴⁺concentration is0.03,the best solvent and solute molar ratio is 1:3,and the best ion exchange time is 45min.?2?High quality K₃AlF₆ crystal was firstly prepared through a two supersaturated crystallization method utilizing K₃AlF₆ and KF as raw materials.Then K₃AlF₆:Mn⁴⁺red phosphor was obtained through ion exchange between K₃AlF₆ and K₂MnF₆.The results show that KF could effectively restrain the hydrolyze of K₃AlF₆ and the optimum molar ratio of KF and K₃AlF₆ is 2.0:1 by orthogonal design.The optimum concentration of solute?K₂MnF₆,K₃AlF₆,KF?in the whole reaction system is 40%.The optimum concentration of hydrogen fluoride in solution consisted by water and hydrogen fluoride is 20%,the optimum reaction time is 18 hours,and the optimum percentage of Mn in K₃Al_1-xMn_xF₆ is x=0.03(K₃Al_0.97Mn_0.03F₆).?3?On the basis of above work,K₂MnF₆ was replaced by CrF_3.Then a new type of remote red light LED fluorescent material(K₃AlF₆:Cr³⁺),which has a wavelength range of 700-800 nm and a peak wavelength of 731 nm,was fabricated by ion exchange between CrF₃ and K₃AlF₆.The results show that the best doping concentration of Cr³⁺is6%,the best system solute concentration is 50%,and the optimum Na₃AlF₆ and K₃AlF₆mole ratio is 0:1,together with the optimum molar ratio?0:1?between NaF and KF.In conclusion,all the aforementioned results established a solid foundation for the development of novel fluorides and far red fluorescent materials as well as new synthesis technologies.