SiO_(2)@Gd_(2)O_(3):Yb^(3+),Ln^(3+)(Ln=Er,Tm,Ho)核壳微球的制备及上转换发光性能

Preparation and upconversion luminescence properties of SiO_(2)@Gd_(2)O_(3):Yb^(3+),Ln^(3+)(Ln=Er,Tm,Ho)core-shell microspheres

为了解决稀土掺杂上转换发光材料价格昂贵且粒径可控性差的问题,采用简单的化学沉淀法以价格低廉且易制备的SiO_(2)微球为核,在其表面均匀包覆了Gd_(2)O_(3):Yb^(3+),Ln^(3+)(Ln=Er,Tm,Ho)壳层,成功合成了球形SiO_(2)@Gd_(2)O_(3):Yb^(3+),Ln^(3+)(Ln=Er,Tm,Ho)核壳上转换发光材料。XRD结果表明,尿素作为沉淀剂优先与稀土离子反应得到SiO_(2)@Gd(OH)CO_(3):Yb^(3+),Ln^(3+)前驱体,经800℃煅烧后壳层进一步转化成结晶性良好的立方相Gd_(2)O_(3):Yb^(3+),Ln^(3+)。SEM和尺寸分布图表明,所制备样品为理想的核壳微球形貌,尺寸均匀,平均粒径约为580 nm。在980 nm激光激发下,SiO_(2)@Gd_(2)O_(3):Yb^(3+),Ln^(3+)(Ln=Er,Tm,Ho)核壳微球分别表现出红光、蓝光、绿光发射,对应于Er^(3+)的4F9/2→4I15/2跃迁、Tm^(3+)的1G4→3H6跃迁及Ho^(3+)的5S_(2)→5I8跃迁,与色度图色坐标发光颜色区域相一致,说明通过简单的调节SiO_(2)@Gd_(2)O_(3):Yb^(3+),Ln^(3+)核壳微球中壳层掺杂的稀土离子种类,成功实现了三色上转换发光。

In order to solve the problem of high price and poor size controllability of rare earth doped upconversion luminescent materials,spherical SiO_(2)@Gd_(2)O_(3):Yb^(3+),Ln^(3+)(Ln=Er,Tm,Ho)core-shell upconversion luminescent materials were successfully synthesized by simple chemical precipitation method using low cost and easy to prepare SiO_(2)microspheres as cores and uniformly coated with Gd_(2)O_(3):Yb^(3+),Ln^(3+)(Ln=Er,Tm,Ho)shells.XRD results show that the SiO_(2)@Gd(OH)CO_(3):Yb^(3+),Ln^(3+)precursor is firstly obtained by the reaction of urea with rare earth ions,then the Gd(OH)CO_(3):Yb^(3+),Ln^(3+)shell is further transformed into cubic phase Gd_(2)O_(3):Yb^(3+),Ln^(3+)with good crystallinity after calcination at 800℃.SEM and size distribution images show that the prepared samples are ideal core-shell microspheres with uniform size,and the average diameter is about 580 nm.Under the excitation of 980 nm,SiO_(2)@Gd_(2)O_(3):Yb^(3+),Ln^(3+)(Ln=Er,Tm,Ho)core-shell microspheres exhibit red,blue and green emissions respectively,corresponding to the 4F9/2→4I15/2 transition of Er^(3+),the 1G4→3H6 transition of Tm^(3+),and the 5S2→5I8 transition of Ho^(3+),which are consistent with the luminescence color region of chromaticity color coordinates,indicating that three color upconversion luminescence is successfully achieved by simply adjusting the doped rare-earth ion species in the shell of SiO_(2)@Gd_(2)O_(3):Yb^(3+),Ln^(3+)core-shell microspheres.