Sm_xLa_(1-x)P_5O_(14)和Dy_xY_(1-x)P_5O_(14)晶体的荧光寿命研究

STUDY OF FLUORESCENT LIFETIMES OF SmxLa1-xP5O14 AND DyxY1-xP5O14 SINGLE CRYSTALS

本文用脉冲衰减法和时间分辨荧光光谱法测量了六种不同稀土离子浓度的Sm_xLa_(1-x)P_5O_4晶体的~4G_(5/2)→~6H_J(J=5/2,7/2,9/2,11/2)四个能级和七种不同稀土离子浓度的Dy_xY_(1-x)P_5O_(14)晶体的~4F_(9/2)→~6H_J(J=15/2,13/2,11/2,9/2)四个能级的荧光寿命和荧光强度。结果指出,在这类晶体中,Sm^(3+)和Dy^(3+)的荧光寿命随着离子的浓度增加而变短,存在着严重的荧光浓度猝灭现象。最后还讨论了浓度与寿命,寿命与荧光强度的关系。

In this paper, fluorescent lifetimes of Sm3+ in SmxLa1-xP5O14 single crystals originating from transitions between 4G5/2 and 6HJ (J = 5/2, 7/2, 9/2,11/2) energy levels and Dy3+ in DyxY1-xP5O14 single crystal originating from transitions between 4F9/2 and 6HJ (J=15/2, 13/2, 11/2, 9/2) energy levels at several concentrations were measured and investigated in detail.The measurement of lifetime was completed by pulse decay curve method and time resolved fluorescent spectrum method, the relative crror<15%. The set-up of lifetime measuring consists of a N2 laser and a photoelectricity detecting system with pulsed gated Boxcar averager.Measurement of fluorescent intensities of the rare earth pentaphosphate single crystals was completed by MPF-4 Fluorimetcr.The relationship between fluorescent lifetime and concentration of rare earth ions in SmxLa1-xP5O14 and DyxY1-xP5O14 single crystal has been found. As shown in Fig.4, there arc different fluorescent lifetimes in different pentaphosphate single crystals. For example, fluorescent lifetime of SmxLa1-xP5O14 and DyxY1-xP5O14 single crystals are ~300us and ~60us at rare earth ion concentration 0.2M, respectively. Fluorescent lifetimes of pentaphosphate single crystals decrease with the increasing of rare earth ion concentration. For. Table 1, fluorescent lifetimes of SmxLa1-xP5O14 single crystal drop from about 30000uS to 13us as Sm3+ concentrations from 0.01M to 1.0M; fluorescent lifetimes of DyxYx -XP5O14 single crystal drop from about 380ns to 7ns as Dy3+ concentrations from 0.05M to 1.0M. Fluorescence decay rate of two kind crystals is different, fluorescence decay rate of SmxLa1-xP5O14 is greater than that of DyxY1-xP5O14. A serious concentration quenching can be observed.The relationship between fluorescent intensities and rare earth ion conccntr- ations in SmxLa1-xP5O1 4 and DyxY1-xP5O14 are described in Fig.7,8.We also discussed relationship of fluorescent intensities and fluorescent lifetimes, of SmxLa1-xP5O14 and DyxY1-xP5O14 single crystals, as Fig.9, 10shown. The experimental regular pattern-agree with equation,i.e. the fluorescent lifetime Te depends ..on non-radiactive transition lifetime f As compared with NdP5O14, Sm3+ and Dy3+ in the same kind structure produced strong concentration quenching. The maximum fluorescence emission obtained from SmxLa1-xP5O14 and DyxY1-xP5O14 arc about 4×1020cm^3 and 9×1019cm^3 respeciivily. Thus it can be seen, that the strong concentration quenching in SmxLa1-xP5O14 and DyxY1-xP5O14 is not due to the structure of the crystal, but the cross relaxation process among mate level pairs, for example 4G5/2-6F8/2 and 6F8/2-6H6/2 energy levels in Sm. La1-xP5O14 and 4F6/2-eF9/2 and 6H9/2-6H6/2 energy levels in DyxY1-xP5O14, as shown in Fig.5,6.