Structural stability, electronic structure and mechanical properties of 4d transition metal nitrides TMN (TM=Ru, Rh, Pd)

• Electronic, structural and mechanical properties of RuN, RhN, and PdN are investigated.
• A pressure induced structural phase transition is predicted under high pressure.
• Electronic structure reveals that these materials exhibit metallic behavior.
• Computed elastic moduli obey traditional mechanical stability condition.
• Among these nitrides RuN is found to be the hardest material.
• The Debye temperature values are computed for RuN, RhN, and PdN.

Ab initio calculations are performed to investigate the structural stability, electronic, structural and mechanical properties of 4d transition metal nitrides TMN (TM=Ru, Rh, Pd) for five different crystal structures, namely NaCl, CsCl, zinc blende, NiAs and wurtzite. Among the considered structures, zinc blende structure is found to be the most stable one among all three nitrides at normal pressure. A structural phase transition from ZB to NiAs phase is predicted at a pressure of 104 GPa, 50.5 GPa and 56 GPa for RuN, RhN and PdN respectively. The electronic structure reveals that these nitrides are metallic. The calculated elastic constants indicate that these nitrides are mechanically stable at ambient condition.