Chemistry Proposal Defense – Henry Anderson

About the event

Speaker: Henry Anderson

Group: Dr. Xiaofeng Guo

Title: Isolating Corrosion Contributions in Rare Earth Disilicate Solid Solutions Through Thermodynamic Methods

Abstract: Rare-earth disilicates are promising environmental barrier coatings to mitigate corrosion in silicon carbide-based turbine systems. However, their application is limited by complex polymorphism and an incomplete understanding of the driving mechanisms of corrosion resistance in multicomponent systems. While recent research has shown that high-entropy disilicates exhibit improved corrosion resistance, preliminary results in two-end member systems indicate that endothermic enthalpies of mixing dominate configurational entropy contributions. It remains unclear whether this trend persists in higher entropy systems, nor is it clear what factors in high-entropy disilicate design contribute to stability.

This project proposes to use thermodynamic methods to decouple enthalpic, entropic, and kinetic contributions to stability in RE disilicate solid solutions. Various disilicate compositions will be synthesized with varying levels of configurational entropy, varying distributions of metal ionic radii, and varying quantities of polymorph-forming disilicates. These compositions will be synthesized with controlled mean ionic radii to isolate the influence of lattice strain, phase separation, and non-ideal mixing on stability. The resulting experimental measurements of enthalpy and entropy will enable the determination of composition-dependent Gibbs free energies of mixing, providing the quantitative basis for extracting interaction parameters and linking observed stability trends to predictive thermodynamic models, including CALPHAD-based assessment of phase equilibria, polymorph stability, and thermodynamic driving forces.