Investigations of the high pressure synthesized osmium carbide by experimental and computational techniques

Abstract

We report the synthesis of hexagonal phase of osmium carbide by high pressure–high temperature technique using laser heated diamond anvil cell. The synthesis is carried out by laser heating the mixture of pure elements, Os and C at pressure of 8 GPa and T ∼ 2000 K. The temperature quenched high pressure phase is characterized by in situ high pressure x-ray diffraction (HPXRD), ex situ transmission electron microscope (TEM) imaging and diffraction. The lattice parameters of novel hexagonal Os2C at ambient pressure are found to be a = 2.536 Å and c = 12.526 Å. First-principle total energy calculations are used for exploring the electronic and mechanical properties of candidate structure types and understanding the synthesized hexagonal-Os2C phase with space group P63/mmc. The calculations reveal that the system is metallic in nature with a fair degree of covalence along the Os–C bond.