Phase transformation pathways of ultrafast-laser-irradiated Ln2O3(Ln=Er–Lu)
| Autor: | Cameron L. Tracy, Wendy L. Mao, Jonathan M. Solomon, Rodney C. Ewing, Steven M. Yalisove, Dylan R. Rittman, Chien-Hung Chen, Mark Asta |
|---|---|
| Rok vydání: | 2018 |
| Předmět: |
Diffraction
Materials science Ab initio 02 engineering and technology 021001 nanoscience & nanotechnology 01 natural sciences Crystallography Transmission electron microscopy Phase (matter) Vacancy defect 0103 physical sciences Production (computer science) Irradiation 010306 general physics 0210 nano-technology Excitation |
| Zdroj: | Physical Review B. 97 |
| ISSN: | 2469-9969 2469-9950 |
| DOI: | 10.1103/physrevb.97.024104 |
| Popis: | Ultrafast laser irradiation causes intense electronic excitations in materials, leading to transient high temperatures and pressures. Here, we show that ultrafast laser irradiation drives an irreversible cubic-to-monoclinic phase transformation in ${\mathrm{Ln}}_{2}{\mathrm{O}}_{3}\phantom{\rule{4pt}{0ex}}(\mathrm{Ln}=\mathrm{Er}--\mathrm{Lu})$, and explore the mechanism by which the phase transformation occurs. A combination of grazing incidence x-ray diffraction and transmission electron microscopy are used to determine the magnitude and depth-dependence of the phase transformation, respectively. Although all compositions undergo the same transformation, their transformation mechanisms differ. The transformation is pressure-driven for $\mathrm{Ln}=\mathrm{Tm}--\mathrm{Lu}$, consistent with the material's phase behavior under equilibrium conditions. However, the transformation is thermally driven for $\mathrm{Ln}=\mathrm{Er}$, revealing that the nonequilibrium conditions of ultrafast laser irradiation can lead to novel transformation pathways. Ab initio molecular-dynamics simulations are used to examine the atomic-scale effects of electronic excitation, showing the production of oxygen Frenkel pairs and the migration of interstitial oxygen to tetrahedrally coordinated constitutional vacancy sites, the first step in a defect-driven phase transformation. |
| Databáze: | OpenAIRE |
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