Er^3＋／Yb^3＋共掺杂ZnO粉末的上转换发光特性

采用高温氧化法制备了Er3 /Yb3 共掺杂ZnO粉。通过X射线衍射和扫描电镜对其进行了成分和组织结构分析,发现样品主要由ZnO和YbF3组成。在ZnO中测量到少量Er3 和Yb3 ,而YbF3中无Er3 ,故发光主要是由ZnO产生的。在980nm半导体激光器的激发下,观察到由处于激发态能级4F9/2,4S3/2,2H11/2和2H9/2的Er3 离子向基态4I15/2跃迁时发出的波长依次为658,538,522和409nm的上转换发光。在488nmAr 激光器的激发下,观察到了较强的409nm的紫光,466和450nm的弱蓝光以及379nm的紫外光,分别对应于Er3 离子的2H9/2→4I15/2,2P3/2→4I11/2,4F3/2/4F5/2→4I15/2,4G11/2→4I15/2等跃迁。上转换发光强度随激发功率的变化关系表明,488nm激发下紫色上转换荧光为双光子过程,主要是通过Er3 /Yb3 离子间正向和反向的能量传递来实现的。

Frequency Up-Conversion Properties of Er3+/Yb3+Co-Doped Zinc Oxide Powders

Er3+ /Yb3+ co-doped ZnO powders were prepared by the high temperature sintering method with starting composition of (mol%) 95ZnF2-4. 8Yb2 O3-0. 2Er2 O3. Microstructure analysis by X-ray diffraction (XRD) showed that the sample consists of two phases, i. e. ZnO and YbF3, which verified that the ZnF2 was oxidized during the high temperatue sintering Composition analysis by scanning electron microscope (SEM) and spectroscopic measurements showed that the Er3+ and Yb3+ ons were successfully used in doping the lattice of ZnO, but most of Yb3+ ions were in the YbF3 phase. These results indicated that the up-conversion luminescence was emitted from ZnO, not from YbF3. Under the excitation of 980 nm diodelaser, four strong up-conversion emissions peaks centered at 658, 538, 522 and 409 nm, corresponding to the transitions 4F9/2 --> 4I15/2, 4S3/2 --> 4I15/2, 2 H11/2 --> 4I15/2 and 2 H9/2 --> I15/2, respectively, were observed. Especially, a strong red up-conversion emission was observed, which is different from that the green up-converted luminescence is dominated in glass and ceramics. Three important cross energy transfer (CRET) processes between Er3+ ions played an important role for this. Under 488 nm Ar+ laser excitation, intense violet (409 nm), weak blue (466, 450 nm) and ultraviolet (379 nm) up-conversion luminescence originating from the transitions 2 H9/2 --> 4I15/2, 2P3/2 --> 4I11/2, 4 F3/2 /4 F5/2 --> 4I15/ 2 and 4G11/2 --> 4 I15/2, respectively, were obtained. The dependence of up-conversion intensities on excitation power indicated that two-photon absorption processes were responsible for the violet luminescence under 488 nm excitation, and the violet up-converted luminescence was achieved through the forward and back energy transfer between Er3+ and Yb3+ ions. Our results show that ZnO as a host material has the potential applications in the up-conversion red phosphors and ultraviolet laser materials.