静电纺丝技术制备Y_2O_3∶Yb~(3+),Er~(3+)上转换纳米纤维及其表征

采用静电纺丝技术制备了PVA/Y(NO3)3+Yb(NO3)3+Er(NO3)3]复合纳米纤维,将其在适当的温度下进行热处理,得到Y2O3∶Yb3+,Er3+上转换纳米纤维.XRD分析表明,复合纳米纤维为无定形,Y2O3∶Yb3+,Er3+上转换纳米纤维属于体心立方晶系,空间群为Ia3.SEM分析表明,复合纳米纤维的平均直径约为150nm;随着焙烧温度的升高,纤维直径逐渐减小.经过600℃焙烧后,获得了直径约60nm的Y2O3∶Yb3+,Er3+上转换纳米纤维.TG-DTA分析表明,当焙烧温度高于600℃时,复合纳米纤维中水分、有机物和硝酸盐分解挥发完毕,样品不再失重,总失重率为83%.FTIR分析表明,复合纳米纤维与纯PVA的红外光谱一致,当焙烧温度高于600℃时,生成了Y2O3∶Yb3+,Er3+上转换纳米纤维.该纤维在980nm的半导体激光器激发下发射出中心波长为521,562nm的绿色和656nm的红色上转换荧光,分别对应于Er3+离子的2H11/2/4S3/2→4Il5/2跃迁和4F9/2→4Il5/2跃迁.对Y2O3∶Yb3+,Er3+上转换纳米纤维的形成机理进行了讨论.

Fabrication and Characterization of Y_2O_3:Yb~(3+) ,Er~(3+) Upconversion Nanofibers by Electrospinning

PVA/Y(NO_3)_3+Yb(NO_3)_3+Er(NO_3)_3] composite nanofibers were fabricated by electrospinning.Y_2O_3:Yb~(3+),Er~(3+) upconversion nanofibers were obtained by calcination of the relevant composite nanofibers. XRD analysis reveals that composite nanofibers are amorphous in structure, and Y_2O_3:Yb~(3+),Er~(3+) upconversion nanofibers are cubic in structure with space group Ia3. SEM images indicate that the mean diameter of the composite nanofibers is ca. 150 nm, and the diameter of the fibers gradually decrease with the increase of calcinations temperature. Y_2O_3:Yb~(3+),Er~(3+) upconversion nanofibers of 60 nm in average diameter were acquired at 600 ℃. TG-DTA analysis reveals that the water, organic compounds, nitrates in the composite nanofibers are decomposed and volatilized totally, and the mass of the sample kept constant when sintering temperature is above 600 ℃, and the total mass loss percentage is 83%. FTIR analysis manifest that the spectrum of the composite nanofibers is basically the same as that of the pure PVA, and Y_2O_3:Yb~(3+),Er~(3+) upconversion nanofibers are formed above 600 ℃. The upconversion spectroscopic properties of the Y_2O_3:Yb~(3+),Er~(3+) nanofibres were investigated under the excitation of a 980 nm continuous wave diode laser. Y_2O_3:Yb~(3+), Er~(3+) nanofibres emitted strong green and red upconversion emissions centering at 521, 562 and 656 nm, respectively. The green emissions were attributed to the transitions of ~2H_(11/2)/~4S_(3/2)→~4I_(15/2) energy levels of Er~(3+) ions, and the red emission was assigned to the transition of ~4F_(9/2)→~4I_(15/2) energy levels of Er~(3+) ions. The formation mechanism of Y_2O_3:Yb~(3+),Er~(3+) upconversion nanofibers was advanced. The technique can be applied to fabrication of other rare earths composite oxides upconversion nanofibers.