Femtosecond Diffraction and Dynamic High Pressure Science

Wark, J. S.; McMahon, M. I.; Eggert, J. H.

doi:10.48550/arxiv.2203.02545

Cited by 1 publication

(1 citation statement)

References 215 publications

(270 reference statements)

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“…Our prediction for the final phase is the following: Above the melting temperature T m (800 K), compression will melt clathrate; between T m and the glass transition temperature T g , compression will result in β-tin recrystallized from supercooled liquid; and finally, at sufficiently low temperature below T g , compression will create a metastable HDA amorphous phase. It might also be possible to monitor the time evolution of the structure across the transition experimentally and to directly detect the presence of the amorphous intermediate, e.g., by means of femtosecond x-ray diffraction [41].…”

Section: Discussionmentioning

confidence: 99%

Pressure-induced structural transformation of clathrate Ge136 via ultrafast recrystallization of an amorphous intermediate

2022

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We study the pressure-induced structural transformation of Ge 136 clathrate by ab initio molecular dynamics and metadynamics. The system under pressure first undergoes amorphization followed by an ultrafast recrystallization to the β-tin structure on the time scale of 30 ps. The initial pressure-induced amorphization of clathrate is triggered by high pressure while the subsequent fast recrystallization to β-tin is driven by low temperature. Interestingly, the amorphous intermediate is still diffusive even at room temperature in spite of very strong undercooling, making the ultrafast recrystallization possible. The system provides an explicit example of structural transformation between two crystalline phases proceeding via noncrystalline intermediate. On fast decompression of the amorphous structure with incipient crystalline order, the recrystallization is blocked and the system instead proceeds to the tetrahedral low-density amorphous (LDA) phase.

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Section: Discussionmentioning

confidence: 99%