Luminescence properties of undoped LiBaAlF₆single crystals

Abstract

This paper presents the results of the study of electronic excitations in undoped LiBaAlF(6) single crystals by means of luminescence spectroscopy and complimentary optical methods. The intrinsic emission at 4.2 eV due to self-trapped excitons was identified. The fast nanosecond defect-related luminescence was revealed at 3.0 eV. Both emissions degrade under electron beam irradiation, the most probable reason of which is defect creation introducing an additional non-radiative relaxation channel prohibiting energy transfer to luminescence centers. These defects can be recovered and luminescence intensity restored at higher temperatures (>200 K). The permanent damage by electron beam irradiation results only in overall growth of the absorption coefficient in the whole 1.5-6.5 eV spectral region studied. The analysis of thermally stimulated luminescence glow curves in the temperature range of 5-410 K revealed two shallow charge carrier traps with the activation energies of 0.22 and 0.33 eV, respectively. The luminescence of an impurity peaked at 2.5 eV was found and tentatively assigned to an oxygen-related emission center.

Optical and luminescence characterization of LiBaAlF6 single crystals

“…From [5] it follows that LBAF single crystal at 10 K has E g = 12.3 eV. This value is fairly consistent with the early reported estimation of E g = 12.1 eV [3]. Crystallographic data for the real LBAF crystals were presented in [6].…”

“…We are aware of only a few research works on this host. Luminescent properties and self-trapped excitons in undoped LBAF crystals have been studied in [3]. From the luminescence optical spectroscopy data it follows that the experimental estimation of the LBAF energy bandgap is E g % 12.1 eV [3].…”

“…Luminescent properties and self-trapped excitons in undoped LBAF crystals have been studied in [3]. From the luminescence optical spectroscopy data it follows that the experimental estimation of the LBAF energy bandgap is E g % 12.1 eV [3]. Luminescence of Pr 3+ ions in LBAF crystals has been studied in [4].…”

The luminescence microspectroscopy of Pr3+-doped LiBaAlF6 and Ba3Al2F12 crystals

“…It is homologous to the above-mentioned LiAEAlF 6 group but has a different, more complex structure described by Merkulov et al (2008). The luminescence properties of undoped LiBAF single crystals have been studied by us (Omelkov et al, 2010). Wet chemical synthesis and luminescent properties of Ce-and Eudoped LiBAF (Belsare et al, 2009a, b) have been briefly reported.…”

Photoluminescence of monoclinic Li3AlF6 crystals under vacuum ultraviolet and soft X-ray excitations

“…This applies not only to study of the crystal structure [9], but also to study of the luminescence and optical properties of both the undoped crystals [10][11][12], and crystals doped with Ce 3+ [13,14], Cr 3+ [15], and Pr 3+ [16]. Electronic properties of undoped Li M AlF 6 crystals have been studied experimentally using vacuum ultraviolet optical and luminescence spectroscopy [12,17], and X-ray photoelectron spectroscopy techniques [17].…”