Tm^(3+)浓度对Y_2(MoO_4)_3∶Tm^(3+),Yb^(3+)荧光粉上转换发光性质的影响(英文)

Effect of Tm^(3+) Concentration on Upconversion Fluorescence in Y_2(MoO_4)_3∶Tm^(3+),Yb^(3+) Phosphors

采用传统的高温固相反应法合成了Tm3+/Yb3+共掺杂Y2(MoO4)3系列荧光粉。XRD结果表明合成的样品为相纯度好的Y2(MoO4)3。在980 nm光激发下,样品具有较强的位于487 nm和800 nm的蓝色和近红外发射,同时伴有较弱的位于649 nm的红光发射。它们分别来自于Tm3+的1G4→3H6、3H4→3H16和G4→3F4跃迁。根据功率相关的上转换发射和能级图分析了Tm3+的上转换发光机制。结果表明,1G4和3H4能级的布居分别来自于三光子和两光子的能量传递上转换。此外,随着Tm3+浓度的增加,蓝色、红色和近红外发射带均呈先增加后降低的趋势,即发生了浓度猝灭。同时,蓝光发射和近红外发射的强度比随Tm3+掺杂浓度的增加而减小。

Tm3+ /Yb3+ co-doped Y2(MoO4)3phosphors with various Tm3+concentrations were prepared via a traditional high temperature solid state reaction method using NH4HF2 as a flux.The microstructure analysis by means of X-ray diffraction revealed that the as-synthesized samples presented a pure phase Y2(MoO4)3.Under 980 nm excitation,intense blue,near infrared(NIR) and weak red upconversion emissions which centered at 487,800 and 649 nm were observed,and these emissions were corresponding to the 1G4→3H6,3H4→3H6and1G4→3F4 transitions of Tm3+,respectively.The upconversion luminescence mechanisms of Y2(MoO4)3∶ Tm3+,Yb3+phosphors were analyzed based upon the power dependent upconversion emissions.The results show that the populations of 1G4 and 3H4 levels come from three- and two-photon energy transfer upconversion processes,respectively.The possible upconversion mechanisms for the blue,red and NIR emissions were discussed based on the energy level diagrams of Tm3+ and Yb3+.In addition,with the increase of Tm3+ concentration,all of the emission bands obviously increase firstly and then decrease,which can be attributed to the concentration quenching.Meanwhile,the intensity ratio of the blue emission and the NIR emission decreases with the increase of Tm3+ concentration.