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Metallurgy of soft spheres with hard core: from BCC to Frank-Kasper phases

2017/07/25 by Brigitte Pansu, Pansu, Brigitte, Jean‐François Sadoc +2
Materials Science · Physics and Astronomy · #Block Copolymer Self-Assembly #FOS: Physical sciences #Material Dynamics and Properties #Polymer crystallization and properties #Soft Condensed Matter (cond-mat.soft) #cond-mat.soft

paper · pdf · doi:10.48550/arxiv.1707.07897

To appear in EPJE

openalex publication_date 2017/07/25 · arxiv created 2017/11/09 · arxiv updated 2017/11/10 · openalex created_date 2022/10/02 · openalex updated_date 2026/07/28

Abstract

Understanding how soft particles can fill the space is still an open question. Structures far from classical FCC or BCC phases are now commonly experimentally observed in many different systems. Models based on pair interaction between soft particle are at present much studied in 2D. Pair interaction with two different lengths have been shown to lead to quasicrystalline architectures. It is also the case for a hard core with a square repulsive shoulder potential. In 3D, global approaches have been proposed for instance by minimizing the interface area between the deformed objects in the case of foams or micellar systems or using self-consistent mean field theory in copolymer melts. In this paper we propose to compare a strong van der Waals attraction between spherical hard cores and an elastic energy associated to the deformation of the soft corona. This deformation is measured as the shift between the deformed shell compared to a corona with a perfect spherical symmetry. The two main parameters in this model are: the hard core volume fraction and the weight of the elastic energy compared to the van der Waals one. The elastic energy clearly favours the BCC structure but large van der Waals forces favors Frank and Kasper phases. This result opens a route towards controlling the building of nanoparticle superlattices with complex structures and thus original physical properties.

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