Self-trapped holes and recombination luminescence in LiBaF3 crystals

We investigated electron paramagnetic resonance (EPR) angular dependencies, recombination afterglow and thermostimulated luminescence of undoped LiBaF 3 crystals, X-irradiated at low temperatures. EPR parameters of the F-2(-) molecule oriented along the [110] direction have been obtained. Based on th e value of the g-shift Deltag = g(perpendicular to) - g(II) = 0.02, charact eristic for the V-K-centres in similar perovskites, we propose that we inde ed observed the V-K-centres, not the H-centres. X-irradiation below 170 K r esults in creation of a long-time temperature-independent afterglow due to the tunnelling recombination between close electron and hole centres, The F -type electron centres and the V-K as well as probably O2- centres are prop osed to be the tunnelling recombination partners, responsible for the 4.1 a nd 3.15 eV luminescence bands, respectively. (C) 2001 Elsevier Science Ltd, All rights reserved.