The bonding characteristics between rare-earth elements and fluorine in fluorozirconate glasses

The bonding characteristics between Rare-Earth (RE) elements and fluorine in fluorozirconate glasses doped with RE fluorides are studied by X-ray absorption near edge structure. The RE elements include La, Pr, Nd, Eu and Er. The intensities of the White Lines (WLs) at RE L_II, and L_III absorption edges in these glasses increase as those in the corresponding fluorides. On the other hand, the WL intensity ratios of L_III to L_II, in the studied materials deviate from the statistical value of two to one, but this deviation in the glasses is also larger than that in the corresponding fluorides. Besides, the changes of the WLs at RE L_{II, III} edges between the glasses containing different RE fluorides and the corresponding fluorides are different for various REs. The reason for these differences is discussed.