Ce3+luminescence in aLiBaF3single crystal at low temperatures

Abstract

The luminescence and decay kinetics of ${\mathrm{Ce}}^{3+}$-based centers in a ${\mathrm{LiBaF}}_3$ single crystal are reported in the 80–300 K temperature range. At about 130 K the leading low-temperature double-peak emission band at 270/296 nm is transformed into a single peak at 325 nm. The transformation is also well reflected in the decay kinetics of both emission bands. A simple two-level model with a separating thermal barrier is used to fit the experimental data. ${\mathrm{Ce}}^{3+}$-excitation-induced interchange of the ${\mathrm{Li}}_{\mathrm{Ba}}$ and ${\mathrm{Ba}}_{\mathrm{Ba}}$ surrounding ions in the [011] and [001] directions, respectively, is proposed to explain the observed band transformation. Thermoluminescence glow curves at low temperatures support the possibility of such ${\mathrm{LiBaF}}_3$ lattice instability.