About Negativity of the Poisson’s Ratio for Anisotropic Materials

摘要

By the example of hexagonal layered and cubic crystals, we give a brief analysis of changes in the Pois son’s ratios with variation of the orientation angles of stretched crystalline samples relative to their crystal lattice. In many cases under discussion, the Poisson’s ratio proves to be either negative or to attain high positive values (higher than 0.5 and even unity). Angular regions of similar extreme behavior are found for this elastic coefficient. Abnormal elastic behavior without restriction on the sign proves to be widely spread among cubic crystals. At the same time, it is only molybdenum disulphide (MoS2) single crystals among the analyzed layered crystals that can have a significant negative Poisson’s ratio.