Dynamics, Structure and Glass Formation of Calcium Aluminate Liquids

TL;DR

This study explores the structure, dynamics, and glass formation of calcium aluminate liquids across an expanded compositional range, revealing fragile-to-strong transitions and polyamorphism through experiments and simulations.

Contribution

It is the first comprehensive analysis linking melt rheology, structure, and glass formation in calcium aluminate liquids over a broad composition range.

Findings

Discovered fragile-to-strong phase transitions in supercooled calcium-aluminates.

Extended the glass-forming region using contactless levitation furnaces.

Quantified thermo-physical and structural diversity, including polyamorphism.

Abstract

Crystalline calcium-aluminates include the phases essential in the setting of Portland cements developed over the last century. It is only within recent decades, however, that calcium-aluminate melts and glasses have begun to attract attention, bringing new functionalities in photonic and electronic applications. These studies, though, have been limited to compositions close to a deep eutectic from where glasses easily form. With the development of contactless levitation furnaces the glass forming region can now be hugely extended. We have taken advantage of these developments to rationalise, for the first time, melt rheology with structural properties across this expanded compositional range, substantiating this with atomistic simulation. In the process, we have discovered that supercooled calcium-aluminates comprise a new system where fragile-to-strong phase transitions are ubiquitous. Taking this holistic approach, we have quantified the common basis of thermo-physical and structural diversity in this novel glass-forming system, together with its inherent polyamorphism.