|About this Abstract
||Materials Science & Technology 2019
||Phase Transformations in Ceramics: Science and Applications
||Changes to the local environment during the entropic phase transformation in high entropy oxides.
||Alexander D. Dupuy, Elke Arenholz, I-Ting Chiu, Padraic Shafer, Yayoi Takamura, Julie M Schoenung
|On-Site Speaker (Planned)
||Alexander D. Dupuy
High entropy oxide (HEO) materials contain at least five oxide components, which form a single phase that is stabilized through configurational entropy. A unique characteristic of HEO materials is their reversible entropy-driven phase transformation between the single phase and multiphase states. Here we explore the changes to the local cation electronic and structural environment in sintered (CoCuMgNiZn)O ceramics during the entropic phase evolution. Using x-ray absorption spectroscopy (XAS) we show that three of the five cations (Co, Cu, and Zn) experience changes in oxidation state and coordination as the phase transformation occurs. Co in particular experiences a complex change to its local environment due to the expected segregation of the Cu-rich multicomponent tenorite phase, as well as the unexpected segregation of a Co-rich phase. Additionally, the behavior of the three cations is strongly influenced by the grain size of the sintered sample.
||Definite: At-meeting proceedings