M. Rabah

Structural stabilities, elastic, and electronic properties of iridium mononitride: a first-principles study

We theoretically study the structural, elastic, and electronic properties as well as the pressure induced solid–solid phase transitions of iridium mononitride (IrN) by using the full potential linear muffin-tin orbital method with the local density approximation as exchange and correlation functional. Six different crystal structures; the zinc-blende (B3), rock salt (B1), wurtzite (B4), NiAs (B81), CsCl (B2), and the tungsten carbide (Bh) have been considered. The transition pressures at which IrN undergoes the structural phase transition from (B3) to (B81), (B1), (Bh), and (B2) phases are calculated. The elastic constants of IrN in its different structures are determined by using the total energy variation with strain technique. The ductility mechanism is discussed via the calculated elastic constants Cij . The Debye temperature of this compound in its stable (B3) phase is estimated from the average sound velocity. Band structure reveals that this compound has a metallic character. The obtained results classified IrN as superhard material in its (B3) phase. To our knowledge this is the first quantitative theoretical prediction of the elastic and high-pressure properties for this compound and still awaits experimental confirmations.