Auxetic Properties of a f.c.c. Crystal of Hard Spheres with an Array of [001]‐Nanochannels Filled by Hard Spheres of Another Diameter

Preliminary results on the influence of periodically distributed cylindrical nanoinclusions introduced into the f.c.c. hard sphere crystal on its elastic properties and the Poisson's ratio are presented. The nanoinclusions are oriented along the [001]‐direction and filled with hard spheres of diameter different from the spheres forming the matrix crystal. The Monte Carlo simulations show that symmetry of the crystal changes from the cubic to tetragonal one. In the case when spheres inside the inclusion are smaller than spheres forming the crystal, the changes of Poisson's ratio are qualitatively similar to the changes observed earlier in the Yukawa sphere crystal, that is, the introduction of nanochannels causes simultaneous decrease of the Poisson's ratio in the [110][10]‐direction, and its increase in [110][001]‐direction. Filling the nanochannel with spheres having diameters greater than that of the spheres in the crystalline matrix, causes a decrease of the Poisson's ratio value from 0.065 down to −0.365 in [111][11]‐direction. The dependence of the minimal Poisson's ratio on the direction of the applied load is shown in a form of surfaces in spherical coordinates, for selected values of nanochannel particle diameters. The most negative value of the Poisson's ratio found amongst all systems studied was as low as −0.873.