2D Structures Exhibiting Negative Area Compressibility

Abstract

This paper proposes an in‐plane negative area compressibility (NAC) material not due to Lifshitz mode, but due to all around in‐plane pressure. The NAC system consists of an array of two‐dimensional material in the form of n‐sided polygon with n/2 number of connecting rods, where n is an even number. Two types of NAC microstructural geometries are introduced herein: 8‐sided polygon in square array and 6‐sided polygon in hexagonal array. The polygons are permitted to change in shape – and hence change in area – at constant side lengths with accompanying translational motion of the connecting rods, thereby changing the overall area of the cell. Results reveal that negative compressibility is observed in the square array NAC when the material shape is in between a regular octagon and a square, and in the hexagonal array NAC when the material shape is in between a regular hexagon and an equilateral triangle.