Department of Physics, Yogi Vemana University, Kadapa 516 003, India.
J Chem Phys. 2010 Mar 21;132(11):114505. doi: 10.1063/1.3352631.
The concentration and pressure dependent luminescence properties of the Tb(3+) ions in a lithium fluoroborate glasses have been studied by analyzing the deexcitation processes of the (5)D(4) level at ambient conditions as well as a function of pressure up to 35 GPa at room temperature. The luminescence spectra of Tb(3+) ions have been measured as a function of pressure and observed a continuous redshift as well as a progressive increase in the magnitude of the crystal-field splittings for the (5)D(4)-->(7)F(3,4,5) transitions. Monitoring the (5)D(4)-->(7)F(5) transition, the luminescence decay curves have been measured and analyzed in order to understand the dynamics of the deexcitation of the Tb(3+) ions in these glasses. At ambient conditions a nonexponential behavior has been found for doping concentrations as low as 0.1 mol % of Tb(4)O(7), although no cross-relaxation channels exist to explain this behavior. The modelization of the energy transfer processes surprisingly shows that the nonexponential character of the decay curves of the (5)D(4) level with concentration or with pressure has to be ascribed to energy transfer to traps without migration of energy between Tb(3+) ions. For all the experimental situations the nonexponential character of the decay curves is well described by the generalized Yokota-Tanimoto model with a dipole-dipole interaction between the Tb(3+) ions and the nearby luminescence quenching traps. The luminescence properties observed with releasing pressure are slightly different to those obtained while increasing pressure suggesting a local structural hysteresis in the lithium fluoroborate glass matrix giving rise to the generation of a new distribution of environments for the Tb(3+) ions.
在室温下，研究了 Tb(3+)离子在氟化锂硼酸盐玻璃中浓度和压力依赖的荧光性质，通过分析（5）D(4)能级的退激发过程来实现。测量了 Tb(3+)离子的荧光光谱作为压力的函数，并观察到连续红移以及（5）D(4)-->(7)F(3,4,5)跃迁的晶场分裂程度逐渐增加。监测（5）D(4)-->(7)F(5)跃迁，测量并分析了荧光衰减曲线，以了解 Tb(3+)离子在这些玻璃中的退激发动力学。在环境条件下，即使不存在交叉弛豫通道来解释这种行为，对于掺杂浓度低至 0.1 摩尔%的 Tb(4)O(7)，也发现了非指数行为。令人惊讶的是，能量传递过程的模型化表明，（5）D(4)能级衰减曲线的非指数特征，无论是与浓度还是与压力相关，都必须归因于无能量在 Tb(3+)离子之间迁移的陷阱能量转移。对于所有实验情况，衰减曲线的非指数特征都可以通过广义 Yokota-Tanimoto 模型很好地描述，其中 Tb(3+)离子和附近的发光猝灭陷阱之间存在偶极-偶极相互作用。在释放压力时观察到的发光性质与增加压力时获得的性质略有不同，这表明在氟化锂硼酸盐玻璃基质中存在局部结构滞后，从而产生了 Tb(3+)离子新的环境分布。
