High pressure and time resolved luminescence spectra of Gd3Ga5O12:Pr crystal

Luminescence spectra and time resolved luminescence spectra of GGG crystal doped with Pr³⁺ were measured at high hydrostatic pressure from ambient to 220 kbar. Effect of pressure results in the red shift of all luminescence lines related to Pr³⁺ ion emission equals from −0.32 to −1.02 cm⁻¹/kbar and in the diminishing of the luminescence lifetimes. The luminescence decay related to emission from ³P₀ state was single-exponential and diminished with pressure from 23 μs at ambient pressure to 6.5 μs at 165 kbar. Luminescence decay related to transition form ¹D₂ state was two-exponential with longer decay equal to 162 μs at ambient pressure and 120 μs at 165 kbar. We discussed effect of pressure on the ¹D₂ → ³H₄ luminescence and emission from ³P₀ state in the context of non-radiative processes that depopulate the ³P₀ and populate the ¹D₂ state, considering mainly multiphonon relaxation processes and depopulation via the praseodymium trapped exciton state.