Size dependent lattice pseudosymmetry for frustrated decahedral nanoparticles

Journal Article · Wed Apr 01 00:00:00 EDT 2026 · Advanced Materials

DOI:https://doi.org/10.48550/arXiv.2507.14781· OSTI ID:3010805

Lin, Oliver ^[1]; Lyu, Zhiheng ^[1]; Ni, Hsu-Chih ^[1]; Wang, Xiaokang ^[1]; Jia, Yetong ^[1]; Hwang, Chu-Yun ^[1]; Yao, Lehan ^[1]; Zuo, Jian-Min ^[1]; Chen, Qian ^[1]

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1. University of Illinois at Urbana-Champaign

Geometric frustration—where geometry prevents simultaneous satisfaction of local interactions—generates pseudosymmetry and emergent behaviors across physical and biological systems. At the nanoscale, pseudosymmetric features in crystalline materials manifest as local strain and distortion, but how they depend on particle size and control structural stability remains unclear. Here, we report the first study of a size-dependent crossover in pseudosymmetry in multi-twinned gold nanoparticles (NPs), combining four-dimensional scanning transmission electron microscopy with nanoscale strain mapping grounded in continuum solid mechanics. Analysis of more than 20 decahedral NPs (20–55 nm) reveals pronounced heterogeneity in multiple modes of in-plane strain and displacement field in small NPs as five tetrahedral grains close the geometric gap, without extended defects. With increasing particle size, strain fields homogenize across grains and local phases shift from predominantly low-symmetry body-centered tetragonal motifs at small sizes to face-centered cubic character approaching the bulk limit. We identify a crossover particle size of ~35 nm, well below bulk, correlating with a transition from modified-Wulff shapes to pentagonal bipyramids, consistent with finite element predictions. This quantitative framework for mapping size-dependent strain and pseudosymmetry enables precise design and control of functional crystalline solids and phase transformation for catalysis, photonics, electronics, and energy storage.

• Research Organization: Board of Trustees of the University of Illinois
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division (MSE)
• Grant/Contract Number: SC0024064
• OSTI ID: 3010805
• Journal Information: Advanced Materials, Journal Name: Advanced Materials
• Country of Publication: United States
• Language: English