Charge and dimensionality effects on the properties of CaNiN

Abstract

Results of first-principles, density-functional, full-potential calculations on crystalline CaNiN and on single chains of NiN and CaNiN are presented. For crystalline CaNiN and single NiN chains we optimized the structural parameters. The role of dimensionality and charge transfer on the electronic structure is investigated by considering various related hypothetical crystalline structures of CaNiN where we have systematically turned off different interactions. This is achieved by expanding the lattice in different directions and/or rotating the layers of the NiN chains as well as considering structures where the Ca atoms have been removed. This is an unusual study of the dimensionality and charge effects in a crystalline compound and, although it is particularly well suited for CaNiN, it could also be applied to other quasi-low-dimensional materials like high-T c superconductors and quasi-one-dimensional spin-density materials. Finally, we explore the magnetic properties of pure CaNiN.

Crystal Chemistry and Electronic Structure of the Metallic Lithium Ion Conductor, LiNiN

“…Given that CaNiN and the title compound share some structural aspects, it is interesting to compare their electronic structure. A strong 1D character to the electronic properties of CaNiN has been demonstrated by Springborg et al However, interaction of the calcium atoms with the Ni−N chains in CaNiN is not solely ionic but also contains a significant covalent component. This confers some “pseudo-three-dimensional” properties to the electronic structure of CaNiN.…”

“…Perhaps unexpectedly, CaNiN is metallic, and no anomalies in the resistivity and magnetic susceptibility have been observed . The electronic structure of CaNiN has been studied a number of times since the discovery of the nitridonickelate. − The initial DFT calculations attributed the absence of distortions to 2D and 3D interchain coupling and a low likelihood of Fermi surface-driven charge density wave (CDW) or spin density wave (SDW) instabilities [NiN 2/2 ] 2- chains in suppressing such instabilities. , There are perhaps two important distinctions between CaNiN and LiNiN which may influence the electronic structure and behavior of the lithium compound.…”

“…The electronic structure of CaNiN has been studied a number of times since the discovery of the nitridonickelate. − The initial DFT calculations attributed the absence of distortions to 2D and 3D interchain coupling and a low likelihood of Fermi surface-driven charge density wave (CDW) or spin density wave (SDW) instabilities [NiN 2/2 ] 2- chains in suppressing such instabilities. , There are perhaps two important distinctions between CaNiN and LiNiN which may influence the electronic structure and behavior of the lithium compound. First, formal electron counting suggests the formulation LiNi(II)N, although the charge balance may be achieved by the formation of holes in bands dominated by N states as proposed for Li 3- x Co x N compounds .…”