Luminescence of F⁺‐type centers in undoped Lu₃Al₅O₁₂ single crystals

Abstract

Undoped single crystals of Lu3Al5O12 annealed in the reduced atmosphere or additively colored in Al vapors were studied at 4.2–400 K by the time‐resolved spectroscopy methods. The 3.15 eV emission, excited in the 3.4, 5.3, and 6.1 eV absorption bands and having a decay time of 3.14 ns at 10 K, was ascribed to the F+‐type centers. It was suggested that these centers consist of an oxygen vacancy with one trapped electron which is perturbed by the neighboring antisite defect (Lu Al3+) or an impurity ion at the Al3+ site. The small Stokes shift and half‐width of the emission band indicate that the F+‐type centers are characterized by a weak electron–phonon interaction.

Time‐resolved spectroscopy of exciton‐related states in single crystals and single crystalline films of Lu3Al5O12 and Lu3Al5O12:Ce

“…The following data indicate to the presence of ${\rm Lu}_{{\rm Al}}^{{\rm 3 + }} {-} {\rm V}_{{\rm O}} $ defects in LuAG SC: In LuAG SC prepared in the reduced atmosphere or additively colored in the Al vapors, the fast 3.15 eV emission was observed in Ref. 44 and ascribed to the F + ‐type centers, consisting of an oxygen vacancy V O with one trapped electron located close to a ${\rm Lu}_{{\rm Al}}^{{\rm 3 + }} $ defect. The comparison of the TSL glow curves reported in Refs. 23, 33, 34 for the X‐irradiated SC and SCF of LuAG allows us to conclude that not only the TSL peaks in the 120–200 K range but also the 280 K peak arises from antisite defects.…”

“…In LuAG SC prepared in the reduced atmosphere or additively colored in the Al vapors, the fast 3.15 eV emission was observed in Ref. 44 and ascribed to the F + ‐type centers, consisting of an oxygen vacancy V O with one trapped electron located close to a ${\rm Lu}_{{\rm Al}}^{{\rm 3 + }} $ defect.…”

“…These peaks can be ascribed to the recombination of thermally released electrons trapped at ${\rm Lu}_{{\rm Al}}^{{\rm 3 + }} $ and ${\rm Lu}_{{\rm Al}}^{{\rm 3 + }} {-} {\rm V}_{{\rm O}} $ , respectively, with the holes trapped at Ce 3+ ions. Indeed, the F + ‐type centers in LuAG are destroying just in this temperature range 44. In the undoped X‐irradiated LuAG SC 23, the appearance of the ${\rm ex}^{0} \{ {\rm Lu}_{{\rm Al}}^{3 + } {-} {\rm V}_{{\rm O}} \} $ emission in the TSL spectrum can be due to the recombination of thermally released holes with the F + ‐type centers.…”

On the mechanisms of radiation damage and prospects of their suppression in complex metal oxides

“…LuAG:Ce 3+ are widely used as fast scintillators. There are many publications relating to optical, luminescent, and thermoactivation characteristics of LuAG:Ce 3+ 43–48. The realization of all the three mechanisms of radiation damage, considered in introduction, is expected in LuAG crystals with high values of mass ratio (Lu/O = 11 and Lu/Al = 6.5) under conditions of superhigh excitation density.…”

Defect Luminescence of Yag Nanopowders and Crystals

“…4c) in the decay kinetics of the 3.1 eV emission for the SCs and NPs studied. This is longer that the decay time of luminescence bands of F + -type centres in YAG SC (3 ns at RT [4]) and LuAG SC (3.14 ns at 10 K [11]) located at 3.1-3.15 eV. The amplitude of afterglow did not exceed 0.01% from that of the fast component.…”