The structural phase transition and elastic properties of IrN under high pressure from first-principles calculations

The structural phase transition and elastic properties of IrN are studied by using the pseudopotential plane wave methods within the Perdew–Burke–Ernzerhof (PBE) form of generalized gradient approximation (GGA). Six candidate structures are chosen to investigate for IrN, namely, rocksalt (B1), cesium chloride (B2), zinc blende (B3), wurtzite (B4), NiAs (B8) and tungsten carbide (Bh) type. On the basis of enthalpy versus pressure is data obtained from the theoretical calculations for high-pressure, the results show that the phase sequence of IrN is B3 → B4 → B8 → B2. The obtained phase transitions are respectively at ca. 1.98, 97.90 and 296.64 GPa. Especially, the elastic properties of B4 IrN under high pressure are studied for the first time. It is found that the elastic constants, the bulk moduli, shear moduli, compressional and shear wave velocities as well as Debye temperature of B4 IrN increase monotonically with increasing pressure. By analyzing G/B, the brittle–ductile behavior of IrN is assessed. This is a quantitative investigation on the structural and thermodynamic properties of IrN, and it still awaits experimental confirmation.

► We find that the phase sequence of IrN is B3 → B4 → B8 → B2.
► The obtained phase transitions are at ca. 1.98, 97.90 and 296.64 GPa.
► The elastic properties of B4 IrN under high pressure are studied for the first time.