烧结温度对Er~(3+)/Yb~(3+)共掺氟氧化物粉末上转换发光的影响

采用高温固相法在600～1100 ℃范围内选择6个不同烧结温度制备了系列相同配方的Er~(3+)/Yb~(3+)共掺氟氧化物上转换发光粉末.在室温下对各样品采用波长为980 nm泵浦光激发,肉眼均可观察到峰值位于658 nm、539 nm和523 nm处的上转换红光和绿光,分别对应于Er~(3+)的~4F_(9/2)→~4I_(15/2)和~4S_(3/2)/~2H_(11/2)→~4I_(15/2)能级跃迁,且红光强度大于绿光强度.通过比较,各样品的上转换图谱形状完全相同,而红绿上转换发光强度明显不同,800 ℃烧结制得样品的红绿荧光强度最强.样品的绿色荧光强度与红色荧光强度的比值随烧结温度升高而增加.通过各样品的X射线粉末衍射图谱(XRD)分析其成分结构,发现烧结温度对样品的成分含量有较大影响.通过测量不同烧结温度下制得样品的上转换发光强度与激发功率的变化关系,发现不同烧结温度可改变样品的上转换发光机理.

Effect of Temperature on Up-converted Fluorescence of Er~(3+)/Yb~(3+) Co-doped Fluoro-oxide Powder

Series of Er~(3+)/Yb~(3+) co-doped fluoro-oxide powder samples with the same composition were prepared at different sintering temperatures. One red up-converted emission band centered at 658 nm and two green up-converted emission bands centered at 539 nm,523 nm were observed under the excitation of an 980 nm semiconductor laser, which corresponded to Er~(3+) ions transitions of ~4F_(9/2)→~4I_(15/2) and ~4S_(3/2),~2H_(11/2)→~4I_(15/2), respectively. And the intensity of red emission is stronger than the green ones. It is concluded by comparing each spectra that, the shape of spectra is similar, but the intisity of emission band is obviously different from each other. The sample sintering at 800 ℃ emits the most intensive luminescence. The ratio of the intensity of red emission(658 nm) to green emission(539 nm) increases monotonously with sintering temperature changing from 600 ℃ to 1100 ℃. XRD data show that the oxidation degree of ZnF_2 has been enhanced by increasing sintering temperature, which changed the microstructure of samples. And then the microstructure influenced up-converted fluorescence properties. The relationship between upconversion intensity and pump power of samples were weasured, and the concerned upconversion processes were discussed in this paper.