In-situ observation of radiation physics and chemistry of nanostructured cerium oxide in water

Muhammad Sajid Ali Asghar, Beverly Inkson, Sudipta Seal, Marco Molinari, Dean Sayle, and Guenter Moebus, 2019

Image courtesy of Protochips

Abstract

Room temperature electron irradiation in aqueous environment is applied to CeO2 nanoparticles using a transmission electron microscope equipped with liquid environmental cell. Oxide dissolution kinetics become accessible at unprecedented scale of spatial and time resolution through irradiation activation of water within a sub-μm size volume, allowing direct measurements of transformation rate and morphologies. Successful live-observation of the formation of nano-needles provides essential inside in how 1D-nanostructures can form. Furthermore, formation of hydrogen bubbles is found and interpreted in relation to the dose needed for ceria dissolution. The results are of importance for many research applications of ceria in water, e.g. for catalysis, environmental remediation, biomedical radiation protection, anti-corrosion coatings, and ultimately via analogy to UO2 also for fission-power fuel engineering and waste disposal.

Impact Statement

Cerium oxide nanoparticles are found in a large range of consumer products and understanding the dissolution and degradation behavior of these materials in water environments Is essential. The electron beam’s influence in in situ liquid cell TEM significantly speeds up many of these kinetic reactions enabling direct, real-time observation of the mechanistic pathways of cerium oxide degradation and dissolution.