XANES studies on Eu-doped fluorozirconate based glass ceramics.

The influence of adding InF as a reducing agent on the oxidation state of Eu in fluorochloro- (FCZ) and fluorobromozirconate (FBZ) glass ceramics was investigated using x-ray absorption near edge (XANES) and photoluminescence (PL) spectroscopy. For both materials, it was found that InF decreases the Eu-to-Eu ratio significantly. PL spectroscopy proved that an annealing step leads to the formation of Eu-doped BaCl and BaBr nanocrystals in the FCZ and FBZ glasses, respectively. In the case of FCZ glass ceramics the hexagonal phase of BaCl could be detected in indium-free and InF-doped ceramics, but only for InF containing FCZ glass ceramics a phase transition of the nanoparticles from hexagonal to orthorhombic structure is observed. For the FBZ glass ceramics, the hexagonal phase of BaBr can be formed with and without indium doping, but only in the indium-free case a phase transition to orthorhombic BaBr could be found.