MSE Colloquium: Dr. Alexandra Navrotsky, Energy Landscapes and Thermodynamic Control of Synthesis Pathways in Complex Ceramics
Many complex ceramic materials can be synthesized in a variety of structural states, with polymorphism, grain size and order-disorder on several length scales among the parameters desirable to be controlled. Such control can be achieved by choosing appropriate initial synthesis conditions and progressing downhill in free energy by appropriate thermal treatment. Understanding the relations among structure, processing and thermodynamic driving forces versus kinetic barriers is critical to choosing a path to desired products. This talk shows how calorimetric study of the closely spaced energetics of various intermediate states provides insight and control into the products formed. Three very different examples illustrate common underlying thermodynamic principles of control. The first is polymorphism and synthesis of new structures in mechanochemical synthesis of metal organic frameworks. The second is control of order-disorder linking pyrochlore, weberite, defect fluorite and amorphous structures, with radiation damage, grinding, and low and high temperature processing as variables. The third is particle size control at the nanoscale in producing thermodynamic crossovers of polymorph stability in simple oxides. In each case, new materials with distinct and interesting properties can be produced by stopping the reactions at intermediate states.
Dr. Alexandra Navrotsky’s research focuses on relating atomic-level structure and bonding characteristics to macroscopic thermodynamic behavior in minerals, ceramics and other complex materials. By advancing high– and low-temperature reaction calorimetry as a foundational research tool, she has contributed to a broad spectrum of applications, from mineral thermodynamics to ceramic processing to zeolites.
Dr. Navrotsky has published more than 900 scientific papers and received many honors, including the Harry Hess Medal, the Goldschmidt Medal, and the Kingery Award. She serves on numerous advisory committees and panels in government and academia, promoting collaborative research across disciplines and institutions.