Ce^(3+)-Gd^(3+)在某些稀土硼酸盐体系中的能量传递

ENERGY TRANSFER OF Ce^+-Gd^(3+) IN RARE EARTH BORATE SYSTEMS

Ce^(3+)离子有一个宽而强的4f-5d吸收带,它能有效地吸收能量。Ce^(3+)离子的荧光寿命非常短,能将能量有效地传递给其它离子起敏化作用。对于Ce^(3+)→Tb^3+),Ce^(3+)→EU^(3+)和Ce^(2+)→Mn^(3+)的敏化作用已有许多报导,并在灯用发光材料上获得应用。Blasse等提出在Ce^(3+)敏化Tb^(3+)时。用Gd^(3+)作中间体能获得高效发光材料。由于Ce^(3+)的5d能级强烈地依赖于基质,其发射波长可以从紫外到红区,而Gd^(3+)的4f-4f跃迁的激发和发射峰值随基质的变化改变不大,因此将有可能呈现不同的Ce^(3+)-Gd^(3+)的能量转移过程。

(Y_(1-x-y) Gd_xCe_y) BO_3 and (La_(1-x-y)Gd_xCe_yMg)B_5O_(10) are different in structure and havebeen synthesized by solid state reactions. Their spectroscopic properties have been studied.The energy transfer between Ce^(3+) and Gd^(3+) in different borate matrix is quite different. In(Y_(1-x-y)Gd_xCe_y)BO_3 the 5d state of Ce^(3+) lies lower in energy than ~6I and ~6P levels of theGd^(3+), so Gd^(3+) in its excited state can thansfer its energy to Ce^(3+); whereas in(La_(1-x-y)Gd_xCe_y Mg)B_5O_(10) the 5d state of Ce^(3+) lies higher in energy than ~6I and ~6P levels of Gd^(3+) andvery close to ~6I, the main excited state of Gd^(3+), hence Ce^(3+) can effectively transfer itsexcited energy to Gd^(3+). Accordingly, the energy transfer between Ce^(3+) and Gd^(3+) is mainlydetermined by the position of Ce^(3+) enrgy levels in different hosts.