In situ atomic-resolution imaging of water vapor-driven multistep oxidation dynamics in strontium cobaltite.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 40845113.
- Also identified by DOI 10.1126/sciadv.adx8890 and PMC identifier 12372878.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Understanding how water vapor interacts with transition metal oxides (TMOs) is critical for tailoring material properties to improve performance and enable new technologies. Despite extensive research efforts, atomic-scale mechanisms underpinning dynamic reactions and reaction-induced phase transitions remain elusive. Here, we use in situ environmental transmission electron microscopy to investigate how water vapor oxidizes vacancy-ordered SrCoO<sub>2.5</sub> at moderately elevated temperatures, demonstrating that water molecules can initiate oxidation more effectively than oxygen under comparable conditions. We discover a distinct "staging" behavior during the oxidation process: A fully ordered intermediate phase, SrCoO<sub>2.75</sub>, forms before transitioning into a near-perovskite SrCoO<sub>3-δ</sub>. In addition, antiphase boundaries, originating at step terraces of SrTiO<sub>3</sub>, alleviate strain by creating reversible nanoscale "gaps" during lattice contraction under oxidation, providing a pathway for preserving structural integrity throughout redox cycling. This work provides atomic-level guidance for engineering TMOs by leveraging water vapor to control their redox behavior and tailor functional properties.