Unravelling the role of titanium in glass melts: a modern systematic approach based on in-situ characterization and containerless melting
Synthesis and Properties of Functional Materials
Thermodynamics and Kinetics as well as Properties of Phases and Microstructure of Materials
Final Report Abstract
The research project targeted the elucidation of the role of TiO2 in (alumino)silicate melts by containerless melting and high-temperature in-situ analytics, taking advantage of the state-ofthe-art experimental facilities available at CNRS CEMHTI in Orléans (France). Although glass synthesis by aerodynamic levitation coupled to laser heating was more challenging than originally expected (melts need to be sufficiently fluid to achieve a stable droplet levitation, high-temperature evaporation is a constant risk), it was possible to adjust the planned experimental approach and shed new light on the behavior of transition metal oxides in glassforming melts. Firstly, it was possible to confirm that Ti4+ is homogenously distributed and assumes a prevalent tetrahedral coordination in SiO2-TiO2 glasses, governing their technologically key properties such as zero thermal expansion. Comparing glasses obtained by melt-quenching and by the sol-gel route, the TiO2 saturation threshold of these materials was identified and set at 10 mol%, independently from the synthesis route. Secondly, the incorporation of TiO2 in more complex matrices (lithium aluminosilicates and sodium aluminosilicates) enabled a clarification of its complex role as "nucleating agent” in commercially available glass-ceramics: although TiO2 addition invariably affects glass stability and crystallization path, it is important to stress that this oxide acts only occasionally as a classical seed former, while it tends to react with other glass components to form more complex phases during devitrification. Thirdly, the acquired understanding of the role of TiO2 in undercooled glass-forming melts was then employed to reinterpret the behavior of basalt melts erupted by Mt. Etna and Stromboli volcanoes, in which nanocrystallization of titanomagnetite can induce an increase in viscosity, affect bubble nucleation and cause explosive paroxysms. This particular study stresses the importance of interdisciplinary research to solve complex scientific questions. Finally, the scope of the project was enlarged by pursuing a number of collateral research topics revolving around the incorporation of transition metal oxides in aluminosilicate glasses. For instance, the saturation limits of ZrO2 in magnesium aluminosilicate glasses were examined to isolate possible compositional strategies for the synthesis of tougher and harder glass-ceramics containing ZrO2 crystals. Glasses containing up to 20 mol% ZrO2 and with interesting phase separated nanostructures could be obtained, paving the way for the development of novel functional materials.
Publications
-
Glass-forming ability and ZrO2 saturation limits in the magnesium aluminosilicate system. Ceramics International, 48(6), 8433–8439.
Zandonà, Alessio; Moustrous, Marine; Genevois, Cécile; Véron, Emmanuel; Canizarès, Aurélien & Allix, Mathieu
-
A chemical threshold controls nanocrystallization and degassing behaviour in basalt magmas. Communications Earth & Environment, 3(1).
Scarani, Alex; Zandonà, Alessio; Di, Fiore Fabrizio; Valdivia, Pedro; Putra, Rizaldi; Miyajima, Nobuyoshi; Bornhöft, Hansjörg; Vona, Alessandro; Deubener, Joachim; Romano, Claudia & Di, Genova Danilo
-
Glass formation and devitrification behavior of alkali (Li, Na) aluminosilicate melts containing TiO2. Journal of Non-Crystalline Solids, 582, 121448.
Zandonà, Alessio; Ory, Sandra; Genevois, Cécile; Véron, Emmanuel; Canizarès, Aurélien; Pitcher, Michael J. & Allix, Mathieu
-
Glass-forming ability and structural features of melt-quenched and gel-derived SiO2-TiO2 glasses. Journal of Non-Crystalline Solids, 598 (2022, 12), 121967.
Zandonà, Alessio; Chesneau, Erwan; Helsch, Gundula; Canizarès, Aurélien; Deubener, Joachim; Montouillout, Valérie; Fayon, Franck & Allix, Mathieu
