Thermally induced ionization of 5d1 state of Ce3+ ion in Gd3Ga3Al2O12 host

We studied the processes occurring in the 5d1 excited state of Ce3+ in Gd3Ga3Al2O12 (GGAG) host. Energy transfer from Gd3+ to Ce3+ was evidenced by photoluminescence excitation spectra of Ce3+ emission. We measured temperature dependences of prompt nanosecond decays and millisecond delayed recombination decays of Ce3+ in GGAG host. The decrease of nanosecond decay times above approximately 200 K is due to thermally induced ionization of the 5d1 excited state of Ce3+. Thermal stimulated luminescence glow curve measurements after X-ray or UV (within 4f–5d1 absorption of Ce3+) irradiation at RT provide another support for the ionization effect around this temperature.