Lanthanide level location and related thermoluminescence phenomena

The location of the ground state energy of a lanthanide ion relative to the valence or conduction band of a host crystal determines whether that lanthanide is a potential electron or a potential hole trap. In this contribution the methods to determine the lanthanide ground state energy are briefly reviewed. Next it will be shown that the temperature of the maximum of the thermo-luminescence glow peak is directly related with the lanthanide ground state energy location. We will use results on a recent study of YPO4:Ce3+YPO4:Ce3+ co-doped with a second lanthanide ion (Nd3+Nd3+, Sm3+Sm3+, Dy3+Dy3+, Ho3+Ho3+, Er3+Er3+, or Tm3+Tm3+) to demonstrate that relationship.