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.
@article{arxiv.2509.10960,
title = {Amorphization-Mediated Si-I to Si-V Phase Transition and Reversible Amorphous-Si-V Phase Memory in Silicon Nanoparticles},
author = {Ziye Deng and Reza Namakian and Wei Gao},
journal= {arXiv preprint arXiv:2509.10960},
year = {2025}
}