Ab initio study of thermodynamic, electronic, magnetic, structural, and elastic properties of Ni4N allotropes

0421173 - ÚFM 2014 RIV US eng J - Journal Article
Hemzalová, P. - Friák, Martin - Šob, Mojmír - Ma, D. - Udyansky, A. - Raabe, D. - Neugebauer, J.
Ab initio study of thermodynamic, electronic, magnetic, structural, and elastic properties of Ni4N allotropes.
Physical Review. B. Roč. 88, č. 17 (2013), Art. no. 174103. ISSN 1098-0121
R&D Projects: GA ČR(CZ) GAP108/12/0311; GA ČR GD106/09/H035; GA AV ČR IAA100100920
Institutional support: RVO:68081723
Keywords : nitrides * ab initio * thermodynamics * elasticity
Subject RIV: BM - Solid Matter Physics ; Magnetism
Impact factor: 3.664, year: 2013

We have employed density functional theory calculations to study the thermodynamic stability and structural, elastic and electronic properties of Ni4N in 8 crystallographic phases. In agreement with experiments, the cubic structure with Pearson symbol cP5, space group Pm-3m (221) is found to be the most stable (and the only stable phase at T = 0 K with respect to decomposition to the elemental Ni crystal and N2 gas phase). We determine structural parameters, bulk moduli, and their pressure derivatives for all eight allotropes. The thermodynamic stability and bulk modulus are shown to be anticorrelated. Comparing ferromagnetic and nonmagnetic states, we find common features between the magnetism of elemental Ni and studied ferromagnetic Ni4N structures. For the ground-state Ni4N structure and other two Ni4N cubic allotropes, we predict single-crystalline elastic constants (in the equilibrium and under hydrostatic pressure), the Young and area moduli, and homogenized polycrystalline elastic moduli. We demonstrate that the elastic anisotropy of the ground-state Ni4N is qualitatively opposite to that in the elemental Ni. One of the studied metastable cubic phases is found auxetic, i.e., exhibiting negative Poisson ratio.
Permanent Link: http://hdl.handle.net/11104/0227595