Watching in situ the hydrogen diffusion dynamics in magnesium on the nanoscale.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 32494706.
- Also identified by DOI 10.1126/sciadv.aaz0566 and PMC identifier 7210000.
- Licence recorded as CC BY-NC.
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Abstract
Active plasmonic and nanophotonic systems require switchable materials with extreme material contrast, short switching times, and negligible degradation. On the quest for these supreme properties, an in-depth understanding of the nanoscopic processes is essential. Here, we unravel the nanoscopic details of the phase transition dynamics of metallic magnesium (Mg) to dielectric magnesium hydride (MgH<sub>2</sub>) using free-standing films for in situ nanoimaging. A characteristic MgH<sub>2</sub> phonon resonance is used to achieve unprecedented chemical specificity between the material states. Our results reveal that the hydride phase nucleates at grain boundaries, from where the hydrogenation progresses into the adjoining nanocrystallites. We measure a much faster nanoscopic hydride phase propagation in comparison to the macroscopic propagation dynamics. Our innovative method offers an engineering strategy to overcome the hitherto limited diffusion coefficients and has substantial impact on the further design, development, and analysis of switchable phase transition as well as hydrogen storage and generation materials.