Compositionally-Complex Fluorite-based Oxides

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NON-TECHNICAL DESCRIPTION: This project explores and expands a new class of compositionally -complex oxides in the fluorite-based crystal structure, which resemble the cubic zirconia gemstone but often contain five or more metal cations. These new materials can exhibit exceptional properties, such as having thermal insulation while being mechanically stiff and hard. This fundamental research delves into a new research field to create new classes of ceramics. Potential applications as new classes of thermal barrier coatings to protect gas turbine engines used in airplanes, ships, and land-based power plants are envisioned. Moreover, creating new thermally insulating ceramics can have impacts in other fields. For example, these materials may be used to increase the efficiency and reduce the cost of solar thermal energy generation in concentrated solar power plants. This project trains and mentors diverse students in a manufacturing-related critical area of ceramic science and technology for the aerospace, defense, and energy industries. TECHNICAL DETAILS: This research project broadens the emerging field of high-entropy ceramics (HECs) to compositionally complex ceramics (CCCs) using the fluorite-based oxides as model systems. This research provides opportunities to tailor and improve properties in a vast compositional space via the interplay between disorder and order. A central scientific hypothesis is that the disorder versus order in CCCs can be utilized to tailor the phase stability, nanoscale heterogeneity, and thermal and mechanical properties, where medium-entropy compositions can outperform their high-entropy counterparts. The fundamental understandings of disorders, short- and long-range orders, oxygen vacancies, and heterogeneity have broad scientific implications. Graduate and undergraduate students are mentored and trained in a critically important mainstay area of ceramic science and technology. Hispanic high school and college students are inspired and trained through summer research projects.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.