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

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 10K, 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-Al(3+)) 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. (C) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim