Cancellation of Auxetic Properties in F.C.C. Hard Sphere Crystals by Hybrid Layer-Channel Nanoinclusions Filled by Hard Spheres of Another Diameter

Abstract

The elastic properties of f.c.c. hard sphere crystals with periodic arrays of nanoinclusions filled by hard spheres of another diameter are the subject of this paper. It has been shown that a simple modification of the model structure is sufficient to cause very significant changes in its elastic properties. The use of inclusions in the form of joined (mutually orthogonal) layers and channels showed that the resulting tetragonal system exhibited a complete lack of auxetic properties when the inclusion spheres reached sufficiently large diameter. Moreover, it was very surprising that this hybrid inclusion, which can completely eliminate auxeticity, was composed of components that, alone, in these conditions, enhanced the auxeticity either slightly (layer) or strongly (channel). The study was performed with computer simulations using the Monte Carlo method in the isothermal-isobaric (NpT) ensemble with a variable box shape.

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

“…This would not have been possible without extensive theoretical studies in the form of basic research [ 42 , 43 , 44 ] or analysis and optimizations [ 45 , 46 ] of novel auxetic model structures and metamaterials. The study of materials with inclusions at the structural level is one of the possible directions of such optimizations [ 47 , 48 , 49 , 50 , 51 ].…”

“…Recently, inclusions in the form of periodic arrays of channels [ 49 ], layers [ 50 ], or their combination [ 51 ] on elastic properties of hard sphere face centered cubic (f.c.c.) crystal, have been investigated.…”

“…The inclusion in the form of an array of nanochannels oriented in -direction filled by particles with larger diameters resulted in a significant enhancement of auxetic properties (e.g., PR in -direction decreased from to , and the minimal value of PR decreased to [ 49 ]), while the inclusion of similar particles forming nanolayers orthogonal to the -direction showed only a slight enhancement of auxetic properties [ 50 ]. A surprising effect has been discovered while studying the effects of hybrid (joined) nanolayer and nanochannel inclusions in one system [ 51 ]. It was found that inclusion in such a form completely eliminated auxetic properties of the system.…”

The Extreme Values of Young’s Modulus and the Negative Poisson’s Ratios of Rhombic Crystals

“…Tretiakov, J.W. Narojczyk, P.M. Piglowski and their collaborators has concerned the auxeticity of 3D model materials with 2D thin layers and 1D narrow channels ("nanolayers" and "nanochannels") [24][25][26][27][28][29][30][31][32]. The auxetic properties of the composites of spherical particles in some main matrix and nanochannels [24,25,[28][29][30] or nanolayers [26,27,31] depended on their orientations, relative particle diameters and filling densities.…”

“…The auxetic properties of the composites of spherical particles in some main matrix and nanochannels [24,25,[28][29][30] or nanolayers [26,27,31] depended on their orientations, relative particle diameters and filling densities. It was shown in [32] that the orthogonal combination of nanochannels and nanolayers can lead, with a sufficiently large size of spherical inclusions, to the absence of auxetic properties of the composite.…”