Structural, mechanical and electronic properties of 4d transition metal mononitrides by first-principles

The structural, electronic and mechanical properties of 4d transition metal mononitrides from YN to CdN are studied by first-principles calculations considering three structures for each nitride, i.e., rocksalt, NiAs-type and WC-type structures. The results indicate that the bulk modulus increases initially, reaches the maximum at MoN, and then decreases. The formation enthalpy tends to increase from YN to AgN. Among the considered structures, rocksalt structure is the most stable for YN, ZrN, AgN and CdN, NiAs-type for the nitrides from MoN to PdN, and WC-type for NbN. The most stable structures for each nitride are mechanically stable, except for PdN. From YN to MoN, the formation enthalpy is negative for the considered structures, indicating that they can be synthesized easily. The density of states shows that only YN is a semiconductor. MoN in NiAs-type structure has the largest bulk modulus 351 GPa and shear modulus 239 GPa among the considered structures.