ZrO2 addition in soda-lime aluminoborosilicate glasses containing rare earths: Impact on the network structure

The influence of increasing ZrO2 content on the structural features of a rare earths (RE = Nd, La) bearing soda-lime aluminoborosilicate glass was investigated through a multi-spectroscopic approach (Raman, Zr-EXAFS, 29Si, 11B, 27Al and 23Na MAS NMR). Particular attention was paid to the modifications occurring in the glassy network and on the distribution of Na+ and Ca2+ ions. Zr4+ ions were shown to be located in (ZrO6)2− sites, connected to the silicate network, and preferentially charge compensated by Na+ ions. A favorable competition of Zr4+ ions against RE3+ ions and (BO4)− entities for charge compensators was observed, but no effect was detected on the environment of (AlO4)− entities. This competition resulted in a modification of the RE3+ ions environment with the ZrO2 content that may affect their solubility in the glassy network.