Copper and nitrogen compounds and silver and nitrogen compounds have been researched with the first-principle linear combination of the atomic orbitals in full-screen basis with the local gradient and hybrid potential of the density functional theory (DFT) realized in the CRYSTAL09 program code. We have found the structural N 2MN (M: Cu, Ag) dinitride-nitride phase having an orthorhombic structure, the spatial group of the Ibam symmetry and four formula units in the primitive cell that have not been reported before. The structure was found to be layered, the metal atoms are linearly circled by the nitride N atoms, whereas, the other two atoms make a molecule with a small negative charge of ∼0.02e. The volume elastic modules in N 2CuN, N 2AgN crystals are equal to 4.3 and 6.6GPa, respectively, and their pressure derivatives are equal to 6.7 and 5.3, respectively. The electron energy spectrum makes a superposition of weakly interacting molecular states of N 2 and metal states of MN. The bandgap width equals ∼0.05eV. The estimations of the enthalpy energies show that N 2MN possess large energy content and in its decomposition into metal and gaseous nitride the energy release can reach 8eVcell -1, which appears to be higher than that in the known metal azides. Thus, the new structure of the dinitride-nitride N 2MN combines the properties of molecular and semiconductor crystals: high compressibility, strong mechanical anisotropy, localized vacant states in the zone spectrum, and small bandgap. The unique physical properties can ensure their application as energy materials, the source of chemically pure nitride, and in semiconductor and optical material science.
ASJC Scopus subject areas
- Condensed Matter Physics
- Electronic, Optical and Magnetic Materials