Eu^(3+)/Yb^(3+)共掺杂ZrO_2粉末的制备和发光性质研究

Preparation and Luminescence of Eu^(3+)/Yb^(3+) Codoped ZrO_2 Powders

利用共沉淀方法制备了Eu3+/Yb3+单掺和共掺的ZrO2粉体材料,研究了煅烧温度和掺杂浓度对结构和发光性质的影响。XRD结果表明:所制备单掺样品含有单斜相和四方相2种不同结构,随着热处理温度的升高,四方相向单斜相转变,经1 150℃处理后,四方相消失,呈现单一的单斜相;Yb3+离子的掺入有稳定ZrO2四方相的作用,随着掺杂浓度的增加,单斜相转变为四方相。由于晶相的不同,Eu3+处在四方相和单斜相2种发光中心,二者发光性质不同。Eu3+/Yb3+共掺后,在270 nm激发Eu3+时,观测到了Yb3+在近红外波段(980 nm)的发光,同时证实Eu3+的激发光谱和Yb3+的激发光谱相一致,表明存在Eu3+到Yb3+的能量传递,交叉弛豫和共合作能量传递过程是其可能的能量传递机理。

Samples of Eu3＋/Yb3＋ co-doped ZrO2 powders were prepared by co-precipitation method.The dependence on the sintering temperature and doping concentration of the structure and luminescence was studied.The results confirmed that the sintering temperature has significant influence on the crystalline phases of ZrO2.As the sintering temperature increased the tetragonal phase was transformed into monoclinic phase.After sintered at 1 150 ℃,single monoclinic phase was observed.In contrast,with the increase in the doping concentration of Yb3＋,the crystalline phase was also changed,and the monoclinic phase was transformed back to tetragonal phase.With 1% Eu3＋ and 10% Yb3＋ doping,single tetragonal phase presents.It was observed that the luminescent properties of Eu3＋ ions in two structures were different.Experiment results reveal that the luminescence can be affected by both sintering temperature and doping concentration.With single Yb3＋ doping,no NIR emission was observed under ultraviolet light excitation（270 nm）.However,with Eu3＋/Yb3＋ codoping,NIR emission around 980 nm from Yb3＋（2F5/2→2F7/2） was observed under the same excitation.Furthermore,it is confirmed that Yb3＋ has the same excitation spectrum with Eu3＋.This down-conversion result indicates that there is an energy transfer process between Eu3＋ and Yb3＋.Cooperative energy transfer process and cross-relaxation process were assigned as the possible mechanism for the near-infrared emission of Yb3＋.