Eu oxidation state in fluorozirconate-based glass ceramics

Abstract

The influence of InF 3 doping and remelting on Eu-doped fluorozirconate-based glass ceramics was investigated using near-edge x-ray absorption and optical spectroscopy. It was found that the addition of InF 3 to the melt decreases the Eu 2+ / Eu 3+ mole ratio, while remelting leads to a significant change in the Eu 2+ / Eu 3+ ratio in favor of Eu 2+ . Photoluminescence spectroscopy shows that additional annealing steps lead to the formation of BaCl 2 nanoparticles in the glass. In as-made glass ceramics containing InF 3 , a phase transition of the nanoparticles from hexagonal to orthorhombic structure is observed. This phase transition is not observed in the remelted glasses studied here.

Optical and selected thermal properties of samarium-doped fluorochlorozirconate (FCZ) glass-ceramics: Formation and growth of BaCl2 nanocrystals in FCZ glass-ceramics

“…Two main peaks A and B may be tentatively associated with Ba-Zr and Na-Zr compounds respectively, while the low temperature crystallization peak D is known to appear in the presence of chlorine, and corresponds to a quasi-superposition of an initial glass transition followed immediately by a partial crystallization of Cl-enriched phase of the glass, leading to the formation of BaCl 2 nanocrystals inside the host glass. This superposition of the glass transition and crystallization regions may vary substantially with the concentration of Cl [11,12] and is discussed later below. It can be clearly seen that there is a large temperature range between the crystallization of the Cl-enriched phase, peak D, and the beginning of the total crystallization of the glass, peak A.…”

XANES Studies on Eu-doped Fluorozirconate Based Glass Ceramics

“…Due to the low Eu-doping level of 3 mol%, the R value is set to 1.5, which was determined for dilute systems from an “in situ” XANES analysis of electrochemical conversion between Eu 2+ and Eu 3+ in a EuCl 3 solution [5]. For the Eu-doped FCZ glasses the curve fitting results and the calculated mole fractions are listed in [2]. …”

“…In such a complex system, the addition of each new chemical and each change in processing affects the material properties. In an earlier work on Eu-doped FCZ glass ceramics, the influence of InF 3 and remelting on the Eu 2+ -to-Eu 3+ ratio was investigated [2]. It was shown that the addition of InF 3 decreases the Eu 2+ -to-Eu 3+ ratio whereas remelting increases the Eu 2+ -to-Eu 3+ ratio.…”

Distribution of luminescent centers in Ce3+-ion doped amorphous stoichiometric glass BaO–2SiO2 and dedicated glass ceramics

“…It was suggested that Eu 3+ -ions delivering the red luminescence are preferably localized in the amorphous glass, while the Eu 2+ -ions emitting in the blue-green region become dominating after partial crystallization of the glass. The results published in [6] showed that the significant amount of Eu 3+ -ions is always present in fluorozirconate based glass ceramics reducing the performance of these materials as both scintillators and storage phosphors. Besides Eu luminescence, strong UV luminescent band was observed in barium disilicate phosphore at the doping with Pb ions [7].…”