| SrAl2O4:Eu2+,Dy3+?SAOED?is kind of inorganic photoluminescence?PL?rare earth long-lasting material,which can be excited by the near UV and visible light in the range of 300-500 nm,and then emit a bright yellowish-green luminescence in darkness for a long time.Because of the advantage of high luminescence intensity,long luminescence duration,low cost,thermostability,environmental friendly,recyclability,and safety,it has been widely applied into the fields of emergency lighting,display,road indication,paints,medical detection,decoration,and textiles.For the textiles,the SAOED was mainly used to produce luminous fiber.Luminous fiber is a new kind of light absorption-reserve-release fiber,which is prepared by adding the rare earth long phosphor into the fiber forming polymer in the spinning process.The luminescence intensity,duration,and color are decided by the rare earth long-lasting phosphor.At present,most of the rare earth long-lasting phosphor for luminous fiber is SAOED,and as a result of the advantages of strong luminescence intensity and long duration,the SAOED luminous fiber has been widely used in home decoration,stuffed toys,lighting clothing,and embroidery,and the demand of it increased rapidly year by year.However,due to the characteristic 4f65d1 to 4f7(8S7/2)transition of the outer electrons of Eu2+,the PL emission spectrum of SAOED consists of a continuous broad band ranging from 450 nm to 650 nm with an single emission peak at 525 nm,leading to the luminescent color of SAOED is yellowish-green,which is too monotonous and cool for textiles.As a result of the fact that people are prefer the warm-toned colors,such as yellow,orange,and red in the field of textile,clothing and home decoration,leading to the application of SAOED luminous fiber is restricted to some extent.With the enrichment of people's spiritual and material life,the yellowish-green luminous fibers cannot satisfy people's demand any more,and people want to have more multicolored luminous fibers for selected,especially for the warm-toned luminous fiber.In order to prepare multicolored luminous fibers,especially for red-emitting one,several yellow-emitting,orange emitting and red-emitting rare earth long-lasting phosphors have been prepared in recent years.However,by the limit of low energy transition of outer electrons of the rare earth ion in the crystal lattice of these warm-toned long-lasting phosphors,the luminescence intensity and duration are relatively low and short,and the redder the luminescent color,the lower and shorter the luminescence intensity and duration,which is not satisfy the application requirement of the luminous fiber.Therefore,exploring an appropriate method to alter the luminescent color of SAOED,and make it to red-shift has important scientific significance and practical value.Aiming at this problem,we proposed a new method to alter the luminescent color of SAOED on the base of the principle of light energy transfer and luminescence superposition.This method was conducted by coating a kind of coumarin red emitting color converter?RECC?on the surface of SAOED.The effect of the concentration of RECC on the luminescence color of SAOED and the red-shift mechanism of the luminescence color were studied.Besides,the application feasibility of the color converter coated SAOED in luminous fiber was also analyzed.The main research work and results are summarized in the following aspects:?1?The SAOED long-lasting phosphor and RECC were prepared by using the high temperature solid state method and cyanidation method,respectively.The micro-morphology,FT-IR spectra,excitation and emission spectra,chromaticity coordinates of SAOED and RECC were characterized,and the conditions for the red-shift of the luminescence color of SAOED initiated by RECC were also studied.The results shown that the excitation spectrum of RECC and the PL emission spectrum of SAOED overlapped in the range of 450-600 nm,implying that the condition for the red-shift of the luminescence color of SAOED was satisfied.?2?SiO2/RECC@SAOED phosphorescent composites were prepared via coating SiO2/RECC on the surface of SAOED,the effect of the concentration of RECC on the luminescence color,intensity and duration of SAOED were studied.The results indicated that the PL emission spectrum of SiO2/RECC@SAOED was composed of the PL emission spectrum of the uncoated SAOED and RECC.The luminescence intensity and duration of SAOED declined a lot after being coated with SiO2/RECC.Besides,the luminescence color of SiO2/RECC@SAOED was the superposition result of the luminescence color of SAOED and RECC,and the red-shift degree of SiO2/RECC@SAOED increased gradually with the increase of the concentration of RECC.?3?PMMA/RECC@SAOED phosphorescent composites were prepared by coating PMMA/RECC on the surface of SAOED,and also the effect of the concentration of RECC on the luminescence color,intensity and duration of SAOED were studied.The results indicated that the effect of PMMA/RECC on the luminescence properties of SAOED were similar with SiO2/RECC.However,the luminescence intensity and duration of SiO2/RECC@SAOED were better than PMMA/RECC@SAOED,whilst the luminescence color of PMMA/RECC@SAOED was redder than SiO2/RECC@SAOED.?4?The dynamic PL emission spectra,luminescence color distribution in CIE LAB color space,and luminescence images of SiO2/RECC@SAOED and PMMA/RECC@SAOED were measured to study the dynamic luminescence color of SiO2/RECC@SAOED and PMMA/RECC@SAOED in darkness.The results shown that both the luminescence color of SiO2/RECC@SAOED and PMMA/RECC@SAOED shown blue-shift and red-shift at the same time in darkness,but the degree of blue-shift was stronger than red-shift,leading to the luminescence color red-shift degree of SAOED decreased gradually,and the higher the concentration of RECC used,the more the red-shift of color decreased.?5?The distribution of PMMA/RECC@SAOED in PAN fiber was better than that of SiO2/RECC@SAOED.When their concentration were less than 15%,both of them could be well-distributed in PAN fiber.The higher the concentration,the redder the luminescence color of the luminous fiber.In addition,the luminescence color of PMMA/RECC@SAOED/PAN fiber was redder than SiO2/RECC@SAOED/PAN fiber when the concentration of PMMA/RECC@SAOED and SiO2/RECC@SAOED contained in fiber were same. |
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