PNNL

Abstract

Isotopic engineering is developing into a key approach to study the nucleation, diffusion, phase transitions, and reactions of materials at an atomic level. It aims to uncover transport pathways, kinetics, and operational and failure mechanisms of functional materials and devices. Understanding these phenomena leads to deeper insights into important physical processes, such as the transport and intercalation of ions in energy conversion and storage devices and the role of active sites and supports during heterogeneous catalytic reactions. Likewise, isotopic engineering is being pursued as a means of modifying functionality to enable future technological applications. In this report, we summarize our recent work employing isotope labeling (e.g., 18O2 and 57Fe) during thin film synthesis and post-growth processing to reveal growth mechanisms, defect chemistry, and elemental diffusion under working and extreme conditions. Isotope-resolved analysis techniques with high spatial resolution, such as time-of-flight secondary ion mass spectrometry and atom probe tomography, facilitate the accurate quantification of isotopic placement and concentration in our well-defined heterostructures with precisely positioned, isotope-enriched layers. Finally, we highlight future research directions that can benefit from the use of isotopically pure materials, such as qubit architectures for quantum information processing. This Account illustrates the great potential of isotopic engineering to enable fundamental mechanistic insights into physical processes and engineer functional properties in epitaxial films, heterostructures, and superlattices.