Kavli Affiliate: Wei Gao
| First 5 Authors: Ziye Deng, Ziye Deng, , ,
| Summary:
Molecular dynamics simulations using a Gaussian Approximation Potential (GAP)
reveal a stress triaxiality driven, two-step Si-I (diamond cubic) to Si-V
(simple hexagonal) phase transition pathway in a spherical Si nanoparticle with
a 10 nm diameter under triaxial compression. A transient amorphous phase first
forms at the surface and propagates inward around Si-I core, where stress
triaxiality is low (shear-dominated). Within the amorphous shell, the material
recrystallizes into Si-V at locations of elevated stress triaxiality and
hydrostatic pressure. The resulting Si-V structure transforms into a fully
amorphous state upon unloading. A subsequent loading-unloading cycle applied to
this amorphous nanoparticle reveals a reversible amorphous to Si-V
transformation, demonstrating a nanoscale phase memory effect.
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