| The development of semiconductor technology,especially the large-scale application of blue light GaN LED chip,makes the field of illumination vary widely.Because of its small size,long service life and energy-saving and environmental protection,W-LEDs have attracted great interest from researchers and are regarded as a new generation of lighting source.At present,the lack of red light component of the commercial W-LEDs has led to the low color index,which limits its application in indoor lighting.In recent years,the fluoride Mn4+ activated red phosphors glow with its unique performance has received the widespread attention,which can absorb blue or near ultraviolet light efficiently and emit efficient linear radiation spectrum in red light district and its application prospect in industry is very broad.In this paper,several Mn4+ activated fluoride/oxyfluoride red phosphors were prepared by the co-precipitation method and the solid-state method.There have been few reports of solid-state method preparation for fluoride/oxyfluoride oxides.We explore some low cost and mind condition ways to compound the Mn4+ activated fluoride/oxyfluoride red phosphors through control the sample composition and synthesis conditions.Herein the microstructure,luminescent properties and reaction mechanism were investigated and discussed in detail by X-ray diffraction(XRD),scanning electron microscopy(SEM)and photo-luminescent spectra(PL)The main contents of the paper are summarized as follows:1.K2NbOF5·KHF2:Mn4+ and K3NbOF6:Mn4+ red phosphors were prepared by a solid-state like strategy.The crystal structure,morphology and doping amount of the K2NbOF 5 · KHF2:Mn4+ and K3NbOF6:Mn4+ red phosphors were systematic investigation.The K2NbOF5·KHF2:Mn4+red phosphor reache its optimum luminous intensity when the real doping amount is 3.93 mol.%.While the K3NbOF6:Mn4+ red phosphor is 4.74 mol.%.The as-prepared K2NbOF5.KHF2:Mn4+ and K3NbOF6:Mn4+red phosphors were used to fabricate W-LEDs devices respectively.The optical performance of these W-LEDs is investigated.The results demonstrate that the added red phosphor K2NbOF5·KHF2:Mn4+ and K3NbOF6:Mn4+ red phosphor can improve the W-LEDs qualities,Obtain higher Ra and lower CCT.2.An environment friendly solid state strategy was designed to prepare K2TiF6:Mn4+ red phosphor without using hydrofluoric acid as the medium.The influence of the molar ratio of the reactants KHF2:K2TiF6 on the phase and luminescence properties of the samples was discussed.It is found that when Mn4+doping amount is certain,K2TiF6:Mn4+ red phosphor of high luminous intensity was prepared when KHF2:K2TiF6 is 3:1.The influence of doping amount of K2TiF6;Mn4+red phosphor on the luminescence properties was discussed.The phosphor reach its optimum luminous intensity when the real doping amount is 6.38 mol.%.The as-prepared N2TiF6:Mn4+ red phosphor,commercially purchased YAG yellow phosphor and blue GaN chip were used to fabricate W-LEDs devices and optical performance of this W-LEDs is investigated.3.BaGeF6:Mn4+ red phosphors were prepared via co-precipitation method.The PL properties,crystal strcture and morphology of the red phosphors were controllable by the amount of precipitation agent,stirring speed and the doping amount of activator.It was found when changes the dosage of BaF2,the emission spectra and morphology of BaGeF6:Mn4+ red phosphor changes regularly.With the increase of activator content,the luminescence intensity of BaGeF6:Mn4+ red phosphors increases first and then decreases.We also discuss the best mixing speed after adding the precipitant and found that BaGeF6:Mn4+ red phosphor had the best performance in all aspects when the mixing speed was 1000 r/min. |
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