Energy Transfer Between Tb[sup 3+] Ions in Y[sub 4−x]Tb[sub x]Al[sub 2]O[sub 9] Phosphor

Abstract

A generally known energy transfer route in Tb 3ϩ activated phosphors is the 5 D 3 → 5 D 4 cross relaxation and the subsequent 5 D 4 → defect impurity quenching. However, this mechanism is not satisfactory to explain the overall feature of measured decay curves of the 5 D 3 → 7 F j transition in the wide range of Tb 3ϩ concentrations. We suggested a new energy transfer scheme, where the 5 D 3 or 4 emission is quenched by the second type of cross relaxations from 5 D 3 or 4 to upper levels such as 5d, charge transfer, and host levels. While neither the rate equation model without the second type of cross relaxations nor Inokuti and Hirayama's equations are well-matched with the measured decay curves, the rate equation model including the second type of cross relaxations is in good agreement with the measured decay curves.We have investigated the energy transfer in Tb 3ϩ activated yttrium aluminate monoclinic ͑YAM͒ phosphors. The analysis of decay kinetics of Tb 3ϩ luminescence has been developed based on the conventional energy transfer scheme, the 5 D 3 → 5 D 4 cross relaxation and the subsequent 5 D 4 → defect impurity quenching. 1-6 On the other hand, there has been little attempt to confirm the presence of other energy transfers, which may take place in Tb 3ϩ activated systems. In addition, whereas the energy transfer in Tb 3ϩ activated yttrium aluminate garnet ͑YAG͒ has been investigated extensively, 1-4 the other Tb 3ϩ activated aluminates could be scarcely found. In this regard, we have investigated the YAP:Tb 3ϩ phosphor before, 7 and the YAM:Tb 3ϩ phosphor is now under our consideration based on a new energy transfer scheme.Raue et al. 8 have proposed that the interactions between excited Tb 3ϩ ions take place, i.e., the second type of cross relaxation ͑or up-conversion͒. In most Tb 3ϩ activated systems, such upper levels as the 5d level of the Tb 3ϩ ion, Tb-O charge transfer level, and host level could participate in this cross relaxation process. These upper levels are symbolized as UL in this paper. Raue et al. 8 also verified experimentally the presence of the second type of cross relaxations using the excited state absorption measurement in several Tb 3ϩ activated phosphors. The analysis of decay kinetics could support such findings, but there has been no decay curve analysis that incorporates this innovative energy transfer scheme. We developed the rate equations corresponding to the new energy transfer scheme, wherein besides the well-were taken into account. The calculated decay curves of 5 D 3 fluorescence based on the rate equation model were then fitted to the measured decay curves for various Tb 3ϩ concentrations. In fact, 5 D 4 fluorescence has been treated more often from the practical point of view. Nonetheless, we employed the decay curves of 5 D 3 fluorescence for the analysis because it has been customary to deal with the donor decay when the theoretical aspect is concerned. Even though the data are not present in this paper, the calculated decay curves of 5 D 4 fluorescence also matched ...

KLaP4O12:Tb3+ Nanocrystals for Luminescent Thermometry in a Single-Band-Ratiometric Approach

“…In order to qualitatively describe the temperature-dependent energy-transfer processes that take place in the Tb 3+ -doped systems, rate equations describing the population of each energy state of Tb 3+ ions were analyzed. We considered the forms of the state equations presented in eqs 1–8 for levels n i , where i = 1, 2, 3, 4, 5, 6, 7, and 8 correspond to the terms 7 F 6 , 7 F 5 , 7 F 4 , 7 F 3 , 7 F 2 , 7 F 1 , 7 F 0 , and 5 D 4 , respectively . The proposed equations cover the generation of transitions matched to GSA ( 7 F 6 → 5 D 4 ) or ESA ( 7 F 5 → 5 D 4 ) induced with a laser of an appropriate excitation wavelength (485 and 543 nm, respectively; Table ).…”

Concentration-dependent luminescence of Tb3+ ions in high calcium aluminosilicate glasses

“…Choi et al [29] and Sohn et al [34] have suggested a second type of quenching mechanism for 5 D 3 and 5 D 4 excited levels based on the excited state absorption by a cooperative energy transfer from 5 D 3 or 5 D 4 levels to the upper laying levels (UL). According to them, this process has been proposed as in three possible ways such as (i) 5 D 4 -7 F 6 ) 5 D 4 -UL;…”

White‐emitting phosphor Ba2B2O5:Ce3+, Tb3+, Sm3+: Luminescence, energy transfer, and thermal stability

“…Upon 262 nm excitation, the emission spectra consist of blue sets at about 420 nm and some peaks from 480 to 650 nm. The blue band originates from 5 D 3 → 7 F 5 transition and the peaks are due to 5 D 4 → 7 F J ( J =6, 5, 4, 3) transitions of Tb 3+ , as shown in Figure B . From the inset, the quenching concentration of 5 D 3 and 5 D 4 is different.…”

“…7 F J (J=6, 5, 4, 3) transitions of Tb 3+ , as shown in Figure 7B. 28 From the inset, the quenching concentration of 5 D 3 and 5 D 4 is different. At low concentration, it mainly emits blue light from the 5 D 3 excited level.…”