Elastic and mechanical properties of hexagonal diamond under pressure

Abstract

Hexagonal diamond is the harder and stiffer alternative of traditional cubic diamond for today’s technology. Although several theoretical attempts have been performed to understand the ground-state elastic properties of hexagonal diamond, little is known about the high-pressure elastic properties of this key material. Unlike previous theoretical methods, we report the application of second-generation reactive bond order potential for the first time to elaborate the pressure-dependent properties of hexagonal diamond in conjunction with geometry optimization calculations up to 500 GPa. Pressure dependency of density, five independent elastic constants, bulk, shear and Young moduli, Poisson ratio, elastic wave velocities, anisotropy parameter, Kleinman parameter, and stability conditions of hexagonal diamond were evaluated. Overall, considered properties of hexagonal diamond display evident increments under pressure, and their ground-state values are in reasonable agreement with available theoretical data. © 2015, Springer-Verlag Berlin Heidelberg.