Ultra-incompressible and hard technetium carbide and rhenium carbide: First-principles prediction

Using density functional theory, the author predicts that the compounds ReC and TcC with the hexagonal WC-like structure are ultra-incompressible and hard materials. This is concluded from the very large bulk and shear moduli. The phonon dispersion reveals no soft modes indicating the stability of the two materials. The calculated density of states shows that ReC and TcC are metallic. The structural and elastic properties of OsC, IrC, and PtC with hexagonal and cubic structure are also investigated for comparison. (C) 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.