Researchers from the Pacific Northwest National Laboratory and other institutions have developed a novel approach to study the properties of zirconia (ZrO2), a material widely used in high-temperature energy applications. The team, led by Ricardo Vidrio and including Yuhan Tong, Junliang Liu, and others, has combined different microscopy techniques to gain a deeper understanding of how nanoscale heterogeneities influence charge transport and mass transfer in oxides.
The researchers focused on thermally grown zirconia on zirconium alloys, which exhibits complex chemical and structural features. They used cross-sectional scanning electron microscope-cathodoluminescence (SEM-CL) to map spatial variations in luminescence in zirconia. This technique was combined with electron backscatter diffraction (EBSD) and electron probe micro-analysis (EPMA) to correlate the luminescence signals with the underlying chemistry and microstructure.
The study found that the SEM-CL signal in zirconia is dominated by a defect band at around 2.7 eV, but its intensity varies significantly across the oxide cross-section. The correlative EBSD-CL analysis revealed that the cathodoluminescence intensity increases with grain area and decreases at the grain boundaries, suggesting enhanced non-radiative recombination associated with microstructural disorder. Additionally, EPMA mapping showed that many of the CL-dark features co-localize with secondary phase precipitates enriched in iron.
These findings highlight the importance of using a multi-modal approach to interpret cathodoluminescence images in complex oxide cross-sections. By connecting electronic properties and luminescence signatures to the underlying chemistry and microstructure, this method provides a pathway to relate local defect landscapes to regions likely to bias electronic/ionic transport during oxidation.
The research was published in the journal Applied Physics Letters, and it offers a promising route for developing advanced materials for energy and electronic uses. Understanding how nanoscale heterogeneities influence charge transport and mass transfer in oxides is critical for improving the performance and lifetime of materials used in high-temperature applications, such as nuclear reactors and solid oxide fuel cells.
In practical terms, this research can help energy sector professionals better understand and control the properties of zirconia and other oxides used in energy technologies. By identifying the specific features that influence electronic and ionic transport, researchers can develop strategies to optimize material performance and extend the lifetime of energy devices. This can lead to more efficient and reliable energy systems, ultimately contributing to a more sustainable energy future.
This article is based on research available at arXiv.