Elastic and piezoresistive properties of nickel carbides from first principles

Abstract

The nickel-carbon system has received increased attention over the past years due to the relevance of nickel as a catalyst for carbon nanotube and graphene growth, where Nickel carbide intermediates may be involved or carbide interface layers form in the end. Nickel-carbon composite thin films comprising Ni 3 C are especially interesting in mechanical sensing applications. Due to the metastability of nickel carbides, formation conditions and the coupling between mechanical and electrical properties are not yet well understood. Using first-principles electronic structure methods, we calculated the elastic properties of Ni 3 C, Ni 2 C and NiC, as well as changes in electronic properties under mechanical strain. We observe that the electronic density of states around the Fermi level does not change under the considered strains of up to 1 %, which correspond to stresses up to 3 GPa. Relative changes in conductivity of Ni 3 C range up to maximum values of about 10 %.

Carbon Modification of Nickel Catalyst for Depolymerization of Oxidized Lignin to Aromatics

“…The optimized lattice constant of bulk fcc Ni, 3.393 Å, is in accord with the experimental value of 3.52 Å . The optimized lattice constants of bulk cubic NiC, a = 4.047 Å, are also quite close to the reported theoretic value, a = 4.073 Å . The Ni(111) surface was modeled using a hexagonal p(2 × 2) supercell with four atomic layers separated by a vacuum with a depth of 15 Å.…”

“…14 The optimized lattice constants of bulk cubic NiC, a = 4.047 Å, are also quite close to the reported theoretic value, a = 4.073 Å. 15 The Ni(111) surface was modeled using a hexagonal p(2 × 2) supercell with four atomic layers separated by a vacuum with a depth of 15 Å. The bottom two layers were fixed to their bulk positions, while the top two layers were allowed to fully relax.…”

In Situ Observations of Phase Transitions in Metastable Nickel (Carbide)/Carbon Nanocomposites

“…Substantial efforts in nonequilibrium deposition techniques, such as sputter deposition, have enabled the controllable fabrication of nanocomposite thin films with thermodynamically metastable filler phases, such as metastable carbides (e.g., Ni 3 C). ,− These metastable filler phases can provide novel functionalities and are hard to obtain in a scalable manner with other deposition techniques. Also bottom-up self-organized nanoscale structuring of filler and matrix phases has been realized. − …”

Influence of Nickel Catalyst Morphology on Layer‐Exchange‐Based Carbon Crystallisation of Ni/a‐C Bilayers

“…First MIC with LE experiments of amorphous carbon (a‐C) were reported by Konno and Sinclair . Following studies of MIC of a‐C focused on the synthesis of graphene by annealing Ni/a‐C bilayers, utilising the small lattice mismatch of nickel (111) and graphene (002) lattice planes and the low solubility of carbon in the nickel lattice . During these studies, models for the mechanisms behind the MIC of a‐C were suggested, employing Raman spectroscopy, electron microscopy and differential scanning calorimetry.…”

“…[3] Following studies of MIC of a-C focused on the synthesis of graphene by annealing Ni/a-C bilayers, utilising the small lattice mismatch of nickel (111) and graphene (002) lattice planes and the low solubility of carbon in the nickel lattice. [8][9][10][11][12][13] During these studies, models for the mechanisms behind the MIC of a-C were suggested, employing Raman spectroscopy, electron microscopy and differential scanning calorimetry. In situ TEM and XRD studies gave insight into the processes during the MIC.…”