Elastic properties of superconducting MAX phases from first-principles calculations

Using first-principles density functional calculations, a systematic study of the elastic properties for all known superconducting MAX phases (Nb2SC, Nb2SnC, Nb2AsC, Nb2InC, Mo2GaC, and Ti2InC) was performed. As a result, the optimized lattice parameters, independent elastic constants, indicators of elastic anisotropy, and brittle/ductile behavior as well as the so-called machinability indexes were calculated. We also derived bulk and shear moduli. Young's moduli, and Poisson's ratios for ideal polycrystalline MAX aggregates. The results obtained are discussed in comparison with available theoretical and experimental data and elastic parameters for other layered superconductors. (C) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim