Ab initio investigation of osmium carbide

Osmium carbide has been synthesized by Kempter and Nadler 46 years ago. According to the authors, OsC crystallizes in WC-type structure and has a hardness equal to 2000 kg mm(-2). Up to date, almost nothing is known about the physical properties of this carbide. We studied electronic, elastic, plastic and mechanical properties of this carbide using an approach based on the density-functional theory. We found that the work of the above mentioned authors is sound. The calculated lattice parameters are in good agreement with that given by Kempter and Nadler and a rough estimate also showed that the measured hardness is reasonable. However, we found that the hexagonal structure of osmium carbide is unstable. (C) 2007 Elsevier Ltd. All rights reserved.