where I(t) is the luminescence intensity at time t, I(0) is the initial luminescence intensity, t is the time, A is the value for different fitting, and τ is the decay time for the exponential components. According to the insert lifetime data, the lifetime decreases from 23.21 to 21.86 μs with increasing Bi3+ concentration in the range of 0.09–0.79 mol%, which may be explained by following reason. When non-radiative decay and radiative decay processes are all present, the experimentally observed decay time of the luminescence is given by following formula (2)[2]:
equation(2)
τ=1/(kr+ki)
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where kr is the probability of radiative decay processes and ki is the probability of nonradiative decay processes from the same state. kr or ki is possible to be increased with increasing activator concentration.
Fig. 6.