Tb^(3+),Yb^(3+)共掺Y_2O_3透明陶瓷的制备及其下转换近红外发光研究

Preparation and Investigation on Down-Conversion Near Infrared Emission of Tb^(3+),Yb^(3+) Co-doped Y_2O_3 Transparent Ceramics

采用真空烧结制备了透明度良好的Tb3+,Yb3+共掺的(Tb0.01Y0.99-xYbx)2O3(摩尔分数x=0,0.02,0.05,0.1)透明陶瓷。在484 nm的蓝光激发下,通过Tb3+离子的敏化作用,实现了Yb3+离子的下转换近红外发光。由Tb3+到Yb3+主要的能量传递机理为:Tb3+吸收484 nm的光子后将所吸收该光子的能量通过合作下转换的方式传递至两个Yb3+离子的激发态2F5/2能级,进而实现两个Yb3+离子的近红外发光。真空烧结对Tb4+的抑制、Y2O3晶格本身对Yb2+的抑制、Tb4+-Yb2+电荷转移态与Tb3+离子5D4能级之间较大的能隙以及Y2O3较低的声子能量等因素使得在484 nm激发下,由Tb3+经Tb4+-Yb2+电荷转移态后部分无辐射跃迁至Yb3+离子2F5/2能级的影响变得较小。另外,Y2O3较低的声子能量加之Tb3+离子5D4能级与Yb3+离子2F5/2能级之间较大的能隙(约1×105cm-1)使得由Tb3+离子5D4能级无辐射跃迁至Yb3+激发态2F5/2,进而实现一个Yb3+离子的近红外发光在下转换近红外发光中的贡献也较小。

Tb3＋,Yb3＋ codoped Y2O3（mole fraction x=0.02,0.05,0.1） transparent ceramics of high transparency have been prepared by vacuum sintering and the down-conversion near infrared（NIR） emission has been demonstrated upon a 484 nm excitation.The dominant energy transfer mechanism is the cooperative down-conversion from 5D4 level of one Tb3＋ ion to the 2F5/2 level of two Yb3＋ ions.The suppression of Tb4＋ during vacuum sintering and the suppression of Yb2＋ due to the nature of Y2O3 lattice,together with the large energy gap between Tb3＋／：5D4 level and Tb4＋-Yb2＋ charge transfer state（CTS） and the low phonon energy of Y2O3 make the non-radiative influence from the CTS negligible.In addition,the contribution of Tb3＋／：5D4→one Yb3＋／：2F5/2（non-radiative）→Yb3＋／：2F7/2（radiative） process to NIR emission should be little due to the large energy gap between Tb3＋／：5D4 level and low phonon energy of Y2O3.