The defect properties of anion-excess alkaline-earth fluorides. I. Low defect concentrations

Modelling and analyzing the glass-like heat transfer behavior of rare-earth doped alkaline earth fluoride crystals

The heat conduction of solids has always been an important issue in material science. Some structure-ordered crystals deliver the heat transfer characteristic similar to amorphous solids, which endows such crystals...

Luminescence Properties and Judd-Ofelt Analysis of Various ErF3 Concentration-Doped BaF2 Crystals

The influence of erbium ion concentration on the optical properties of BaF₂:ErF₃ crystals was investigated. Four ErF₃ concentration (0.05, 0.08, 0.15 and 0.5 mol% ErF₃)-doped BaF₂ crystals were obtained using the Bridgman technique. Room temperature optical absorption in the 250–850 nm spectral range was measured, and the photoluminescence (PL) and decay times were also investigated. The Judd–Ofelt (JO) approximation was used, taking into account four absorption peaks (at 377, 519, 653 and 802 nm). The JO intensity parameters, Ω_t (t = 2, 4, 6), were calculated. The influence of the ErF₃ concentration on the JO parameters, branching ratio, radiative transition probability and radiative lifetime were studied. The obtained results were compared with measured values and with those reported in the literature. Under excitation at 380 nm, the well-known green (539 nm) and red (668 nm) emissions were obtained. The calculated and experimental radiative lifetimes were in millisecond range for green and red emissions. The intensity of the PL spectra varied with the Er³⁺ ion concentration. The emission intensity increased linearly or exponentially, depending on the ErF₃ concentration. Under excitation at 290 nm, separate to the green and red emissions, a new UV emission band (at 321 nm) was obtained. Other research has not reported the UV emission or the influence of ErF₃ concentration on emission behavior.

Reversible polarized bleaching in hydrogenated rare-earth-doped fluorites

By using site-selective laser spectroscopy, several sites in hydrogenated and deuterated rare-earth-doped fluorite crystals have been found to exhibit reversible bleaching. The site orientations can be switched between orthogonal directions by corresponding changes in the laser polarization. Such effects are a form of photochemical hole burning and are attributed to laser-induced migration of H(-) or D(-) ions between equivalent interstitial positions adjacent to the rare-earth ion.