Schematic outlining some potentially tunable properties of interest with the addition of various elements to (Mg,Co,Cu,Ni,Zn)O high entropy oxide.
2x2x2 supercell of rare-earth HEO, F1, in a fluorite (a) and bixbyite (b) structure with an oxygen vacancy and its diffusion path along the x-axis indicated by the black arrow. (c) A possible migration configuration for the hop mechanism showing the Ce-Pr migration edge (middle) and the initial (left) and final (right) vacancy positions. Polyhedra rotated for clarity.
Computational investigation of high-entropy crystals within an inter-disciplinary research group. Most classical computational discovery paths are enthalpy stabilized, however instead, configurational disorder is employed as the thermodynamic driver to realize new crystalline solids. This work explores complex oxides with cation sublattices populated by many elements at random, known as high entropy oxides (HEOs). This research, which is part of the Materials Research Science and Engineering Center (MRSEC), explores the crystal chemistry rules of entropy-driven phases in search of transformational advances in materials properties by integrating synthesis, characterization, theoretical development, and computational modeling. Our current computational investigations are focused on the prototypical HEO, J14 [(Mg, Co, Cu, Ni, Zn)0.2O], as well as the leading HEO example for ionic conduction, F1 [Ce, La, Pr, Sm, Y)0.2O2-δ] where δ is some amount of oxygen vacancies. The investigators of this work acknowledge the funding from the National Science Foundation (NSF), the Penn State MRSEC-Center for Nanoscale Science under award number DMR-2011839.
Students working on projects in this area are Mary Kate Caucci and Jacob Sivak.
Publications
“Chemical Environment and Structural Variations in High Entropy Oxide Thin Film Probed with Electron Microscopy”, L. Miao, J.T. Sivak, G. Kotsonis, J. Ciston, C.L. Ophus, I. Dabo, J.P. Maria, S.B. Sinnott, N. Alem, ACS Nano 2024 18(23), 14968-14977. DOI: 10.1021/acsnano.4c00787
“Fluorite-structured high-entropy oxide sputtered thin films from bixbyite target”, G.N. Kotsonis, S.S.I Almishal, L. Miao, M.K. Caucci, G.R. Bejger, S.V.G. Ayyagari, T.W. Valentine, B.E. Yang, S.B. Sinnott, C.M. Rost, N. Alem, J.P. Maria, Appl. Phys. Lett., 2024 124(17), 171901. DOI: https://doi.org/10.1063/5.0201419
“What is in a name: Defining “high entropy” oxides”, B. Matthew, M. Gazda, V. Keppens, A.R. Mazza, S.J. McCormack, A. Mielewczyk-Gryn, B. Musico, K. Page, C.M. Rost, S.B. Sinnott, C. Toher, T.Z. Ward, A. Yamamoto, APL Mater. 2022 10(11), 110902. DOI: https://doi.org/10.1063/5.0122727