Removing Auxetic Properties in f.c.c. Hard Sphere Crystals by Orthogonal Nanochannels with Hard Spheres of Another Diameter.

Jakub W Narojczyk,Dmitrij Morozow,Przemysław Kędziora,Mirosław Rucki,Krzysztof W Wojciechowski,Joseph N Grima,Mikołaj Bilski

doi:10.3390/ma15031134

Abstract

Negative Poisson’s ratio materials (called auxetics) reshape our centuries-long understanding of the elastic properties of materials. Their vast set of potential applications drives us to search for auxetic properties in real systems and to create new materials with those properties. One of the ways to achieve the latter is to modify the elastic properties of existing materials. Studying the impact of inclusions in a crystalline lattice on macroscopic elastic properties is one of such possibilities. This article presents computer studies of elastic properties of f.c.c. hard sphere crystals with structural modifications. The studies were performed with numerical methods, using Monte Carlo simulations. Inclusions take the form of periodic arrays of nanochannels filled by hard spheres of another diameter. The resulting system is made up of two types of particles that differ in size. Two different layouts of mutually orthogonal nanochannels are considered. It is shown that with careful choice of inclusions, not only can one impact elastic properties by eliminating auxetic properties while maintaining the effective cubic symmetry, but also one can control the anisotropy of the cubic system.

Highlights

Negative Poisson’s ratio (PR) [1] materials, or auxetics [2], as they are commonly referred to, are a relatively new class of materials exhibiting unusual elastic properties
Studies showed that periodic arrays of nanochannel inclusions of particles with increased diameters, introduced in one of the principal crystallographic directions (e.g., [001]), substantially decrease the PR, improving the auxetic properties of such systems [49]
Such a hybrid inclusion completely removes the auxetic properties from the system [51]

Summary

Introduction

Negative Poisson’s ratio (PR) [1] materials, or auxetics [2], as they are commonly referred to, are a relatively new class of materials exhibiting unusual elastic properties. The ever growing interest in auxetics was sparked by the early theoretical [4,5,6,7] and experimental [8] studies performed in the 1980s This interest is motivated by the vast potential applications [9,10,11,12] of materials that expand their transverse dimensions when stretched longitudinally (to point only one highly characteristic feature [13]). Since their discovery, auxetics have been extensively studied both theoretically [14,15,16,17,18] by computer simulations [19,20,21] and experimentally [22,23,24]. The study of materials with inclusions at the structural level is one of the possible directions of such optimizations [47,48,49,50,51]

Methods

Results

Conclusion