Improved photoluminescence property by homogeneous deposition-precipitation method for Eu2+ doping in Si–N–O frameworks

Abstract

The highly dispersed Eu2+ activators with improved photoluminescence property have been successfully achieved by a homogeneous deposition-precipitation (DP) process and the followed heat treatment using SrSi2O2N2 lattice as the typical Si–N–O frameworks. The phase composition, photoluminescence properties and surface states were investigated by XRD, fluorescence spectrophotometer, FESEM and XPS. Compared with the sample prepared by traditional solid state reaction (SSR) method, the luminescence intensity of the SrSi2O2N2: Eu2+ phosphor prepared by DP method exhibits an enhanced luminescence intensity with 1.4 times for green emission peak at 529 nm under excitation of 370 nm. The homogeneous DP process facilitates the uniform distribution of Eu2+ activators in the Si–N–O frameworks and results in a slower decreasing tendency between emission intensity and Eu2+ concentration. The results of FESEM and decay times indicated that the phosphors prepared by DP and SSR method exhibit the characteristic folded platelet-like morphology and similar fluorescence lifetime (918.4 ns and 914.4 ns, respectively). The XPS results revealed that the amount of Sr–O bands in the phosphor prepared by DP method is much higher than that in the sample prepared by SSR method. Interestingly, the SrSi2O2N2: Eu2+ phosphor can be obtained through this DP method even at a low heat treatment temperature (800 °C) under a strongly reducing atmosphere. It is suggested that the deposition-precipitation process will be an efficient synthetic strategy to construct uniform Eu2+ distribution in Si–N–O frameworks and further to enhance the luminescence intensity of the SrSi2O2N2: Eu2+ phosphor.