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Structure, mechanical, electronic, and thermodynamic properties of marcasite‐structure TMN 2 (TM = Ru, Rh, Os, and Ir) under high pressure: A first‐principles study
Author(s) -
Dong Bing,
Liu Ke,
Zhou XiaoLin,
Tan Jiao,
Mao XiaoChun,
Chang Jing
Publication year - 2016
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.201552545
Subject(s) - pseudopotential , orthorhombic crystal system , density functional theory , nitride , metastability , chemistry , formula unit , thermodynamics , castep , crystallography , materials science , computational chemistry , atomic physics , crystal structure , physics , organic chemistry , layer (electronics)
The structural, mechanical, and electronic properties of four orthorhombic noble‐metal nitrides TMN 2 (TM = Ru, Rh, Os, and Ir) (space group of Pnnm, No: 58) under 100 GPa were investigated through the first‐principles calculation using the generalized gradient approximation within the plane‐wave pseudopotential density‐functional theory. The obtained equilibrium structures are in excellent agreement with other experimental and theoretical results. The calculated formation energy indicates that the nitrides are thermodynamically metastable but mechanically stable at zero pressure. The calculated B / G ratio indicated RhN 2 possesses a ductile nature at 0 GPa, while RuN 2 , OsN 2 , and IrN 2 are prone to brittleness under pressures of around 20.8, 20.0, and 4.3 GPa, respectively. Then, we calculated the partial and total densities of states. The results show that these four noble‐metal nitrides are metallic and the order of metallicity from high to low is: RhN 2 > IrN 2 > RuN 2 > OsN 2 . Through the charge‐density distributions, we find that strong covalency is present in the interstitial dinitrogen units for the four orthorhombic compounds. The calculated hardness of orthorhombic RuN 2 , RhN 2 , OsN 2 , and IrN 2 are 13.66, 11.54, 16.33, and 17.92 GPa, respectively. Through the quasiharmonic Debye model, we also investigated the thermodynamic properties of these four compounds.