iridium carbide

Comparison of the Performance of Iridium Carbides with Different Stoichiometric Ratios

Li, Xiang, et al. The Journal of Physical Chemistry C, 2011, 115(14), 6948-6953.

This work used the first-principles method to study iridium carbides with different stoichiometric ratios and compared the structure, mechanical stability and physical properties of various iridium carbides. The important conclusions are as follows:
· The iridium carbides possessing iridium germanium structures exhibit notably high values for bulk modulus, B, shear modulus, G, and elastic constants. The presence of entirely positive eigenvalues in the elastic constant matrix indicates their elastic stability.
· Among these carbides, RhSn2-IrC2 stands out with the highest bulk modulus, highlighting its exceptional incompressibility. In the case of iridium carbides with iridium germanium structures, the values of shear modulus and G/B ratio tend to increase alongside carbon content, with the exception of Ir4C5.
· Unlike other examined iridium carbides, Ir4Ge5-Ir4C5 acts as a semiconductor with an indirect band gap of 0.5 eV.
· The low B/G ratio observed in TcP3-IrC3 and IrGe4-IrC4 suggests their brittleness.
· Trigonal IrGe4-IrC4, while not displaying the highest energetic stability, boasts significant mechanical strength due to a higher bulk modulus, superior shear modulus, and minimal Poisson's ratio.
· With such promising physical characteristics, tetragonal Ir4Ge5-Ir4C5 and trigonal IrGe4-IrC4 emerge as appealing candidates for advanced superhard and highly incompressible materials.