Redox-induced crystallisation in Ti-bearing glass-forming melts: a Ti K-edge XANES study
Résumé
Ti is usually tetravalent in silicate glasses. It may be trivalent under very reduced conditions, but this remains unclear. In this study, in situ Ti K-edge XANES experiments were performed on four different Tibearing melts, equilibrated at high temperatures using a micro-furnace with controlled atmosphere. No formation of Ti 3+ was observed, even at fO 2 ~ 10-15 (estimated). Instead, systematic crystallization of the melts was observed. In experiments at fO 2 ≤ 10-12 , the system favours Ti 4+ crystallization instead of reduction to Ti 3+ in the studied melts. Fluxing melts with reduced gas mixtures, like Ar-2% H 2 , may be a novel way to induce surface crystallisation and produce ceramic-coated glass materials.
Domaines
Planète et Univers [physics]
Origine : Fichiers produits par l'(les) auteur(s)