Normally, when we talk about the thermal quenching mechanism of the luminescence of the 5d energy level, two main ways are usually considered:

1. the 5d electron goes back to the 4f groud state via the crosspoint through the configuration coordinate diagram.

2. the 5d electron delocalizes to the conduction band.

For the system where the 4f has more than one electron, such as Eu2+, Pr3+, the above way can simultaneously effect the thermal quenching properties of the 5d electron. However, for the system that the 4f has only one electron, namely Ce3+, how can the 1 way contribute the thermal quenching mechanism?

Does the second way determine the thermal stability of Ce3+ activated phosphor?