UC San Diego

Functional materials with tunable chemical, electronic, and magnetic properties play a pivotal role in advancing modern technology and addressing critical global challenges. A detailed understanding of the structure-property relations in these materials can unlock breakthroughs in their development. Nanoscale structures can have profound effects onthe functionality of a material. This dissertation presents how advanced coherent X-ray techniques can be used to probe these nanoscale structures. In particular, Bragg coherent diffractive imaging is used to map lattice strain and defects, while resonant elastic X-ray scattering can probe nanoscale magnetic domains. The results in Chapter 3 demonstrate the superior electrochemical homogeneity of cathode material fabricated using a novel dry approach, compared to the conventional slurry method, helping to explain observed performance improvements. We further observe a gradient in the electrochemical performance of the cathode as a function of distance from the battery separator. Chapter 4 is an investigation of the strain and defects found in a novel Na-Y-Zr-Cl solid-state electrolyte, as well as the co-existence of two competing crystalline phases. Finally, Chapter 5 presents the discovery of an anomalous order in Fe electrons in magnetite (Fe3O4) thin films with a strong magnetic signature. Based on the modeling of the observed reciprocal space structure, this order is likely to be ultra-thin spin domains with a thickness of 0.5 unit cells.