Developments in Ceramic Materials Research

86
ln(I transfer (t))
-4.2
-4.4
-4.6
-4.8
-5.0
T. T. Basiev, V. A. Demidenko, K. V. Dykel’skii et al.
-lg[-ln( I transfer (t) )]
2
1
0
Gd 2 O 2 S:Nd 3+ (0.5 w.%)
1 2 3
lg t
t 1/2 , μs 1/2
1 /2
a)
Gd 2 O 2 S:Nd 3+ (0.5 w.%)
γ=0.030 μs -1/2
CDA = 3.8*10 -39 cm 6 /s
0 5 10 15 20 25
Figure 31. Nonradiative energy transfer kinetics from the 4 F 3/2 manifold of the Nd 3+ ion in the
Gd2O 2S:Nd 3+ (0.5 wt%) ceramic samples at 300 K: −lg[−ln I(t)] as a function of lg t—a and ln I(t) as a
function of t 1/2 —b.
The reason of it is a correlation between the dominant multipolar mechanism of energy
transfer and the square of the reduced matrix elements U (k) of electronic transitions
participating in the energy transfer [62]. All three matrix elements U (2) , U (4) and U (6 can be
responsible for dipole transition in both the donor and the acceptor but for quadrupole
transition only one matrix element U (2) matters. Only nonzero matrix element U (2) gives
contribution to quadrupole part of energy transfer. If one analyzes the matrix elements of the
transitions participated in the cross-relaxational energy transfer from the 4 F3/2 metastable level
of the Nd 3+ ion, namely, ( 4 F3/2→ 4 I13/2; 4 I9/2→ 4 I15/2) and ( 4 F3/2→ 4 I15/2; 4 I9/2→ 4 I15/2) he finds that
b)