Oxides with High Entropy

Author:

Almishal, Saeed

Graduate Program:

Materials Science and Engineering

Degree:

Doctor of Philosophy

Document Type:

Dissertation

Date of Defense:

December 19, 2024

Committee Members:

Venkatraman Gopalan, Major Field Member
Jon-Paul Maria, Chair & Dissertation Advisor
Vincent Crespi, Outside Unit & Field Member
Long-Qing Chen, Major Field Member
John Mauro, Program Head/Chair

Keywords:

Entropy
Thin Films
Pulsed Laser Deposition
Bulk Ceramic Synthesis
Chemical Disorder
Correlated Electron Oxides
Epitaxy

Abstract:

The hunt for new phases of matter is among the most exciting endeavors in materials research. The excitement originates from the active property engineering possibilities and advanced technology opportunities that serve societal needs. Oxides with high entropy emerge as a parallel approach to the near-saturated enthalpy-driven exploration of complex oxides. In this entropy-enabled approach, many cations are distributed at random among a single sublattice creating a high degree of configurational disorder. These high-entropy configurations can be kinetically trapped at ambient conditions, forming metastable states that are chemically disordered yet positionally ordered. This thesis delves into the design, synthesis, and functional properties of these kinetically metastable phases. The core of this work explores the entropy-enabled configurational landscape across temperature, time, and chemical potential space, uncovering pathways to expand the discovery space of complex oxide materials, and potentially engineer novel functionalities.