Thermoluminescence investigation of donor (Ce3+, Pr3+, Tb3+) acceptor (Eu3+, Yb3+) pairs in Y3Al5O12

The thermoluminescence properties of Y3Al5O12 (YAG) doped with an electron donor lanthanide (Ce3+, Pr3+, or Tb3+) together with an electron acceptor lanthanide (Yb3+ or Eu3+) were studied with the aim to locate the energy levels of each divalent and each trivalent lanthanide within the band gap. The activation energies needed to liberate electrons trapped by Yb3+ or Eu3+ were determined from thermoluminescence heating rate plots. With an automated thermoluminescence excitation spectroscopy technique, information on the energy level location of the electron donors Ce3+, Pr3+, and Tb3+ was obtained. By combining all data with an empirical model, a scheme containing all the divalent and trivalent lanthanide energy levels in YAG has been constructed.