| About this Abstract |
| Meeting |
MS&T24: Materials Science & Technology
|
| Symposium
|
High Entropy Materials: Concentrated Solid Solutions, Intermetallics, Ceramics, Functional Materials and Beyond V
|
| Presentation Title |
Oxygen Vacancy Formation Energetics in MgO-Based High Entropy Oxides from DFT and Experimental Validation |
| Author(s) |
Oriyomi Opetubo, Ting Shen, Rajendra Bordia, Dilpuneet S. Aidhy |
| On-Site Speaker (Planned) |
Oriyomi Opetubo |
| Abstract Scope |
In contrast to single or double cation based oxides, high entropy oxides (HEOs) consist of equi- or near equimolar concentation of multiple cations randomly distributed on a crystal lattice. The random distribution causes a wide diversity of nearest-neigbor environments around oxygen atoms. Consequently, a range of bonding environments and oxygen vacancy formation energies are observed. We investigate oxygen vacancy formation energies in Mg(ZnCoNiCu)O-based HEO using density functional theory (DFT). We find that vacancy formation energy trends are controlled by the cation charge. We explicitly determine the effect of all cations on formation energies. Experimentally, a series of binary, ternary, quaternary and quinary HEOs are synthesized using a simple and scalable polymeric steric entrapment method. By annealing in inert environment, oxygen vacancies are analyzed by XPS and TGA. The experimental obseravtions agree with our DFT calculations. This understanding contributes to oxygen vacancy transport useful in microstructure evolution and electrochemical applications. |