Partially Auxetic Properties of Face‐Centered Cubic Hard‐Sphere Crystals with Nanochannels of Different Sizes, Parallel to [001]‐direction and Filled by Other Hard Spheres

Results of constant pressure and temperature Monte Carlo (MC) simulations with varying shapes of the periodic box are presented for face‐centered cubic (FCC) hard‐sphere crystals with periodic inclusions––arrays of channels parallel to the crystalline axis and forming a square lattice with and axes in the plane. The channels, referred to as nanochannels because their diameters do not exceed a few lattice constants of the matrix crystal, are filled by hard spheres of slightly different diameters from the spheres forming the matrix crystal. Fourteen types of nanochannels with different sizes, formed by the spheres lying on the nanochannel axis and up to those being their thirteenth nearest neighbor, are simulated. The nanochannel axes are distanced by six lattice constants of the monoatomic FCC crystal and arranged in a square lattice with main axes parallel to one of the main axes of the FCC lattice, formed by identical spheres. It is shown that small differences in: 1) channel sizes, 2) their geometry; and 3) diameter ratios of inclusion to matrix spheres can lead to large differences in the elastic properties of the studied nanocomposite structures. This is well seen in the minimum and maximum values of Poisson's ratio.