Atomic-Scale Characterization of Impurity Enrichment to High-Purity Alumina Lattice Defects.

High-purity alumina (HPA) is a cornerstone material in advanced energy and electronic technologies necessary for the global energy transition. Traditionally, HPA is routinely studied using bulk analytical techniques, which overlook nanoscale inhomogeneities. However, as industrial demand shifts toward increasingly higher purity standards, a fundamental understanding of the structural and chemical nanoscale characteristics of HPA becomes essential. In this study, electron microscopy and atom probe tomography are used to reveal that crystallographic defect structures within HPA act as major sinks for bulk impurities. These impurities are preferentially accumulated via dislocation-mediated diffusion. These findings challenge the conventional homogeneous view of pure bulk materials and show that HPA can be chemically and structurally inhomogeneous at the nanoscale level. The results highlight the critical role of nanoscale characterization of high-end materials and reveal new opportunities to develop innovative pathways for precision design and manufacturing of next-generation high-performance materials.