Crystallization characteristics and chemical bonding properties of nickel carbide thin film nanocomposites

Abstract

The crystal structure and chemical bonding of magnetron-sputtering deposited nickel carbide Ni₁-xCx (0.05 ⩽ x⩽0.62) thin films have been investigated by high-resolution x-ray diffraction, transmission electron microscopy, x-ray photoelectron spectroscopy, Raman spectroscopy, and soft x-ray absorption spectroscopy. By using x-ray as well as electron diffraction, we found carbon-containing hcp-Ni (hcp-NiCy phase), instead of the expected rhombohedral-Ni₃C. At low carbon content (4.9 at%), the thin film consists of hcp-NiCy nanocrystallites mixed with a smaller amount of fcc-NiCx. The average grain size is about 10-20 nm. With the increase of carbon content to 16.3 at%, the film contains single-phase hcp-NiCy nanocrystallites with expanded lattice parameters. With a further increase of carbon content to 38 at%, and 62 at%, the films transform to x-ray amorphous materials with hcp-NiCy and fcc-NiCx nanodomain structures in an amorphous carbon-rich matrix. Raman spectra of carbon indicate dominant sp(2) hybridization, consistent with photoelectron spectra that show a decreasing amount of C-Ni phase with increasing carbon content. The Ni 3d-C 2p hybridization in the hexagonal structure gives rise to the salient double-peak structure in Ni 2p soft x-ray absorption spectra at 16.3 at% that changes with carbon content. We also show that the resistivity is not only governed by the amount of carbon, but increases by more than a factor of two when the samples transform from crystalline to amorphous.

Fabrication of NiC/MoC/NiMoO4 Heterostructured Nanorod Arrays as Stable Bifunctional Electrocatalysts for Efficient Overall Water Splitting

“…As shown in Figure a and Figure S3 in the Supporting Information, a set of strong Raman bands for both NiMoO 4 and annealed NiC/MoC/NiMoO 4 ‐30 were observed at 818, 892, and 940 cm −1 , which were consistent with previously reported Mo−O vibrations of NiMoO 4 . A new band located at 181 cm −1 in the spectrum of NiC/MoC/NiMoO 4 ‐30, and another two bands, denoted as the D and G bands, could be ascribed to the new materials NiC and MoC, owing to the similarity of the D and G bands in NiC and MoC . These Raman features revealed the existence of NiC, MoC, and NiMoO 4 in the sample after carbonization.…”

Self‐Construction from 2D to 3D: One‐Pot Layer‐by‐Layer Assembly of Graphene Oxide Sheets Held Together by Coordination Polymers

“…At least seven peaks are found in the C1 sX PS spectrum after deconvolution. [11] Additionally,f our types of carbon atoms in different functional groups can be observed:non-oxygenated ring (284.5 eV), C-O (286.01 eV), C=O( 288.42 eV), and O-C=O( 292 eV). [11] Between these two peaks,athird feature at 284.3 eV can be assigned to sp 2 hybridized carbon atoms in C = Cb onds.…”

“…Thep eak at 283.3 eV is assigned to NiÀCbonds, [11] with asecond peak at 285.5 eV assigned sp 3 -hybridized carbon atoms in CÀC bonds. At least seven peaks are found in the C1 sX PS spectrum after deconvolution.…”

Investigation of multilayered TiSiC/NiC protective coatings

“…Consequently, they are considered as promising candidates for tribological applications [31,38,39], as well as for high performance electrical sliding contacts [32,35]. The NiC coatings exhibit a low level of internal stress, superior friction characteristics and significant variation of the electrical conductivity with the carbon concentration [42][43][44][45][46][47]. Therefore, these coatings have been subject of growing interest due to their possible use in both tribological and electrical applications.…”

“…Therefore, these coatings have been subject of growing interest due to their possible use in both tribological and electrical applications. Also, a particular interest to the study of TiSiC and NiC films was determined by the large variety of nanocrystalline and amorphous (a) phases, with different properties, which can be formed in TiSiC (TiC, Ti 5 Si 4 , Ti 3 SiC 2 , Ti 4 SiC 3 , Ti 5 Si 3 C x , SiC, a-C sp 2 and a-C sp 3 [33,34,38,40]) and NiC (Ni, NiC x , Ni 3 C, a-C sp 2 and a-C sp 3 [45,47]) systems. Combining TiSiC and NiC films in a multilayered architecture to form a non-isostructural system is expected to lead to superior film characteristics as compared to those of TiSiC and NiC monolayers.…”