Poisson's Ratio of f.c.c. Hard‐Sphere Crystals with Cubic Supercells Containing Four Nanochannels Filled by Hard Spheres of Another Diameter

Abstract

It is known that a face centered cubic (f.c.c.) crystal of identical hard spheres containing a periodic array of nanochannels, oriented along one of the principal crystallographic directions and filled by hard spheres of another diameter, shows a significant decrease of its Poisson's ratio with respect to pristine crystal. This indicates an essential enhancement of auxetic properties by such nanoinclusions. The present work describes studies of the f.c.c. hard‐sphere crystal containing four nanochannel arrays, oriented along the [ 111 ] direction and its images with respect to cubic symmetry group transformations and selected in such a way as to not affect the symmetry of the crystal. The elastic properties of the current model are analyzed under different thermodynamic conditions and for different sizes of inclusions. These studies reveal that the auxetic properties of the system vanish when the diameters of inclusion spheres are greater than the ones forming the matrix f.c.c. crystal and, in the case of the widest nanochannels, also when these diameters are smaller. The studies are performed by Monte Carlo computer simulations in the isothermal–isobaric (NpT) ensemble, using the Parrinello–Rahman approach.

Variability of Elastic Properties of Two-Layered Tubes from Six-Constant Tetragonal Crystals

“…A change in auxeticity occurs in the presence of defects in cubic crystals. The role of one-dimensional and two-dimensional defects, such as nanochannels and nanolayers, in model cubic crystals has been studied in a number of works: [34][35][36][37][38][39][40][41][42][43][44][45]. The auxeticity of cylindrically anisotropic crystalline tubes from cubic and six-constant tetragonal crystals was investigated partially in [46,47].…”