XANES studies on Eu-doped fluorozirconate based glass ceramics

The influence of adding InF₃ 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 InF₃ decreases the Eu²⁺-to-Eu³⁺ ratio significantly. PL spectroscopy proved that an annealing step leads to the formation of Eu-doped BaCl₂ and BaBr₂ nanocrystals in the FCZ and FBZ glasses, respectively. In the case of FCZ glass ceramics the hexagonal phase of BaCl₂ could be detected in indium-free and InF₃-doped ceramics, but only for InF₃ 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 BaBr₂ can be formed with and without indium doping, but only in the indium-free case a phase transition to orthorhombic BaBr₂ could be found.