Temperature dependence of the Pr³⁺ luminescence in LSO and YSO hosts

The temperature dependences of photoluminescence spectra of Pr³⁺ in Lu₂SiO₅ (LSO) and Y₂SiO₅ (YSO) hosts under excitation into the 5d₁ excited state are reported within 4-450 K together with measured decay times of the fast and slow delayed recombination decay processes. Ionization processes occurring from the 5d₁ relaxed state are evaluated using the mentioned decay measurements. The simple kinetic model is created to provide quantitative parameters of energy barriers and frequency factors, which govern the ionization process in the 5d₁ Pr³⁺ excited state in both hosts. The ionization barriers are interpreted as the separation between the conduction band and the 5d₁ excited state. The temperature dependences of the Pr³⁺ 5d₁-4f and 4f-4f luminescence intensities point to the thermally stimulated transition from 5d₁ state towards the ³P₂ and other lower lying 4f levels.