Thermally-induced ionization of the Ce3+ excited state in SrHfO3 microcrystalline phosphor

We measured temperature dependences of emission spectra, prompt nanosecond decays and millisecond delayed recombination decays for the Ce3+ center in the SrHfO3 (SHO) host. We characterized two samples with 0.1% and 5%Ce prepared by the acetate and citrate combustion and solid state reaction, respectively. The decrease of nanosecond decay times above approximately 220 and 260 K, respectively, is due to thermal ionization of 5d1 excited state of the Ce3+ center. Energy barrier of 300 meV, governing this process, is calculated for both the 0.1% and 5%Ce:SHO samples. Thermoluminescence glow curve measurement after X and UV (310 nm) irradiation at RT provides another support for the 5d1 excited-state ionization of Ce3+ in the SHO host.