Preparation Of Eu³⁺ Codoped YAlO₃ Phosphors By Coprecipitation Synthesis And Their Luminescent Properties

The luminescence materials based barium hexaaluminate has been investigated extensively for its high luminous efficiency and the good stability characteristic of chemical properties. YAlO3 is good materials of the laser matrix and the scintillation because of its chemical stability,insolubile in organic acid and alkali,big density,hing mechamical strength,high thermal congucitivity and thermal diffusion coefficient etc. Conventionally,the aluminates phosphors were prepared by solid state reaction required firing temperature in the range of 16001800℃. The method not only needs high temperature,but also brings in impurities. The resulting large size phosphors were ground to obtain fine powder that caused the decreasing of the luminescent efficiency. Recently,phosphors of hexaaluminates were prepared by chemical coprecipitation,sol-gel technique,hydrof hermal processing,microwave heating method and combustion synthesis. And some achievements in these preparation proceeding have been achieved. Chemical coprecipitation as a solution-based method,which allows mixing of precursors at the molecular level has an advantage in the preparation of aluminates phosphors. In this paper,we prepared red phosphor YAlO3:Eu3+ by chemical coprecipitation. We also conducted a series of experiments researching with the aids of the measure methods such as XRD,SEM,DTA,Fluorescence spectrophotometer and so on. The major work is summarized as the following.(1) We prepared YAlO3 Precursor in the coprecipitation system by dispersion technique. Some factors in the coprecipitation process such as concentration of cation and precipitators,the pH value of the system,dropping velocity of cation,rection temperature,sintering temperature,were researched. We obtained the optimal processing parameters.(2) We prepared YAlO3.Eu3+ by the same processing parameter. XRDanalysis shows X-ray diffraction patterns of YAlO3:Eu3+is the same with that of YAlO3, which attributed to Eu3+ partly occupied Y3+ cells. Fluorescence analysis shows,under ultraviolet excitation with a wavelength of 398nm,the 612nm emission peak of phosphors which is obviously high than the emission peak 589nm. It indicated that Eu3+ preperred to occupy a low symmetry site.(3) Phosphor luminous intensity is different in different concentration of doped Eu3+. It found that the optimal concentration of doped Eu3+ was 3mol%. The excessing concentration caused the decreasing of the luminescent efficiency as its "concentration destroy".(4) The phosphor Eu3+ Cu+ doped in YAlO3 were prepared by chemical precipitation,fluorescence analysis shows that the incorporation of Cu+ ions greatly enhanced the luminescence intensity due to its sensitization effect. The wave functions of the emission spectrum Cu+and the inspire spectral Eu3+ were partly overlapped in theoretically.