# How to manipulate nanoparticle morphology with vacancies

**Authors:** Ilia Smirnov, Zbigniew Kaszkur, Riccardo Ferrando  
**arXiv:** [2409.01254](https://arxiv.org/abs/2409.01254)  
**Date:** 2024-09-02  
**Summary page:** https://www.summarizepaper.com/en/paper/2409.01254v1/

## Key points

- Researchers explore impact of stacking defects in noble metal nanoparticles on optical, catalytic, and electrical properties
- Introduction of novel mechanism called vacancy-driven twinning transforms fcc gold structures into hcp configurations
- Computational simulations demonstrate creation of realistic multi-twinned nanoparticle models
- Use of multidomain X-ray diffraction method to quantitatively assess degree of twinning in structures
- Presentation of various models illustrating different spatial arrangements of vacancies within nanoparticles
- Configuration #3 stands out with unique XRD pattern showing additional peak at ~53.2 degrees corresponding to hcp gold phase
- Molecular dynamics simulations show stability of model #3 up to its melting temperature
- Potential stability and utility of vacancy-driven twinning in manipulating nanoparticle morphology for materials science and nanotechnology applications

## Summary

In the study "How to manipulate nanoparticle morphology with vacancies," researchers explore the impact of stacking defects in noble metal nanoparticles on their optical, catalytic, and electrical properties. Previous research has investigated the mechanisms behind these defects, but there is still a significant gap in understanding how to intentionally manipulate the bulk morphology of nanoparticles. The authors introduce a novel mechanism called vacancy-driven twinning, which transforms face-centered cubic (fcc) gold structures into locally hexagonal close-packed (hcp) configurations. Computational simulations demonstrate how this approach allows for the creation of realistic, randomly multi-twinned nanoparticle models. Using a multidomain X-ray diffraction method (MDXRD), they quantitatively assess the degree of twinning in these structures, bridging theoretical studies with practical applications and developing tools for modifying and controlling fcc nanoparticle structure. The study presents various models illustrating different spatial arrangements of vacancies within the nanoparticles, ranging from weakly defected structures to strongly defected ones. Among these models, one particular configuration (#3) stands out due to its unique XRD pattern with an additional peak at ~53.2 degrees corresponding to the hcp gold phase. This configuration features a 6-layer thick hexagonal phase that penetrates the entire cluster, resembling experimentally observed fcc-2H-fcc gold nanorods. Furthermore, molecular dynamics simulations using a semi-empirical potential show that model #3 remains stable up to its melting temperature. This finding highlights the potential stability and utility of vacancy-driven twinning in manipulating nanoparticle morphology for various applications in materials science and nanotechnology.