Novel Material Development. Thermodynamic Engineering. Structural Characterization.
The need for improved technologies across a broad range of applications demands development and discovery of novel materials to set a new technological precedent. Our focus is on the synthesis and characterization methods of such novel and advanced materials. We are specifically interested in gaining fundamental insight into the structure-process-property relationships in advanced oxide ceramics created through thermodynamic engineering via configurational entropy. Some of our current research efforts are highlighted below!
Localized structural disorder in high entropy and entropy-stabilized ceramics.
The intrinsic properties we observe in materials are a direct consequence of their composition and local structure. High entropy ceramics do not have a primary composition, rather they are a near-equimolar distribution of several elements where no single element serves as host. Such compositional disorder is accompanied by a unique distribution of localized structural distortions that can have a profound effect on properties such as thermal conductivity, diffusion, magnetic interaction, and more. Using extended x-ray absorption fine structure (EXAFS), we are able to determine localized structure and composition around specific cation species. We use EXAFS in conjunction with complementary, larger scale techniques including x-ray diffraction (XRD) and STEM-EDS, enabling a multi-length scale understanding of the disorder in these type of systems.
Figure 1. Fitted Fourier transform of EXAFS around the Co absorber, 7709 eV. Chi(R) and imaginary part of Chi(R) for MgCoNiCuZnO5 thin films grown at (left) 300 °C and (right) 400 °C. EXAFS data collected at beamline 10-BM, Advanced Photon Source, Argonne National Laboratory.
Figure 2: Long-range assumptions vs. short-range reality. EXAFS measurements enables us to understand the local disorder around specific elemental species, strengthening our understanding of some of the unique properties being studied in this new class of materials.