Luminescence of Ca(NbO 3) 2:Pr 3+ at ambient and high hydrostatic pressure

Abstract

In this contribution, photoluminescence and time-resolved photoluminescence spectra of Ca(NbO 3) 2 doped with Pr 3+ obtained at high hydrostatic pressure up to 72 kbar applied in a diamond anvil cell are presented. At ambient conditions, the emission spectrum obtained in the time interval 0–1 μs is dominated by spin-allowed transitions from the 3P 0 state. On the other hand, transitions from 1D 2, characterized by a decay time equal to 30 μs dominate the steady-state luminescence. At pressures lower than 60 kbar, the continuous wave emission spectrum consists of sharp lines peaking between 600 and 625 nm, related to the 1D 2→ 3H 4 transition and three lines at 500, 550 and 650 nm related to emission transitions originating from the 3P 0 level of Pr 3+. The emission from the 1D 2 excited state depends weakly on the pressure. Its decay time decreases from 33 μs at ambient pressure to less than 22 μs at 68 kbar. On the other hand, the 3P 0 emission is strongly pressure dependent. At pressures of 60 kbar and higher, the Pr 3+ emission intensity from the 3P 0 state decreases. This is accompanied by a strong shortening of the luminescence decay time. The observed pressure quenching of the f–f emission transitions and the concomitant lifetime shortening have been attributed to increasing crossover from the 3P 0 state of Pr 3+ to a Pr 3+-trapped exciton state.