Raman spectroscopic studies of stress-induced structure alteration in diamond-like carbon films

Zhu, Wenliang; Arao, Kazuyuki; Nakamura, Morimasa; Takagawa, Yuka; Miura, Kenichiro; Kobata, Junpei; Marin, Elia; Pezzotti, Giuseppe

doi:10.1016/j.diamond.2019.02.020

Cited by 24 publications

(11 citation statements)

References 35 publications

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“…Yet that reduction was not accompanied by so significant downshift of G peak position. While, according to Zhu et al [37], in the case of undoped DLC films, the downshift of G peak position was at the level of several cm −1 , or no shift was found despite significant stress changes in 3 GPa range. Therefore, possible reduction of the internal stress in DLC:Si films cannot explain such a significant G peak downshift.…”

Section: Structurementioning

confidence: 84%

Diamond Like Carbon Films Containing Si: Structure and Nonlinear Optical Properties

et al. 2020

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In the present research diamond-like carbon (DLC) films containing 4–29 at.% of silicon were deposited by reactive magnetron sputtering of carbon target. Study by X-ray photoelectron spectroscopy revealed the presence of Si–C bonds in the films. Nevertheless, a significant amount of Si–O–C and Si–Ox bonds was present too. The shape of the Raman scattering spectra of all studied diamond-like carbon containing silicon (DLC:Si) films was typical for diamond-like carbon. However, some peculiarities related to silicon doping were found. Studies on the dependence of DLC:Si of the optical transmittance spectra on the Si atomic concentration have shown that doping by silicon affects linear, as well as nonlinear, optical properties of the films. It is shown that the normalized reflectance of DLC:Si films decreased with the increased exciting light fluence. No clear relation between the normalized reflectance and photoexcited charge carrier relaxation time was found. It was suggested that that the normalized reflectance decrease with fluence can be related to nonlinear optical properties of the hydrogenated diamond-like carbon phase in DLC:Si film.

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Section: Structurementioning

confidence: 84%

Diamond Like Carbon Films Containing Si: Structure and Nonlinear Optical Properties

et al. 2020

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“…The intensity ratio R ( I D / I G ) reflects the structural characteristics of the carbon nanomaterial. A smaller ratio represents a higher degree of graphitisation and a lower degree of disorder 67,68 . As shown in Figure 12, the value of I D / I G decreases with increasing the relative Ni content in the catalyst, suggesting that the CNTs obtained with the 40%Ni‐10%Co/SBA‐15 catalyst have the highest degree of graphitisation and minimal disorder.…”

Section: Resultsmentioning

confidence: 93%

“…A smaller ratio represents a higher degree of graphitisation and a lower degree of disorder. 67,68 As shown in Figure 12, the value of I D /I G decreases with increasing the relative Ni content in the catalyst, suggesting that the CNTs obtained with the 40%Ni-10%Co/SBA-15 catalyst have the highest degree of graphitisation and minimal disorder. Gallego et al 30 reported a value of I D /I G = 0.6 for CNTs prepared by ethanol catalytic decomposition.…”

Section: Tga Of the Deposited Cntsmentioning

confidence: 91%

Simultaneous production of hydrogen and carbon nanotubes from cracking of a waste cooking oil model compound over Ni‐Co / SBA ‐15 catalysts

Liu

2020

Int J Energy Res

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Hydrogen is considered an ideal energy carrier. However, the use of fossil fuels to produce hydrogen depletes natural resources and causes environmental problems. Therefore, there is an urgent need to find alternative raw materials and technologies for the production of hydrogen. Waste cooking oil (WCO) is a renewable energy source that has emerged as a potential raw material for hydrogen production. This study describes the production of hydrogen and carbon nanotubes (CNTs) by catalytic cracking of a WCO model compound (WCOMC) performed in a lab-scale fixed bed using Ni-Co/SBA-15 catalysts. The phase, structure and reduction properties of the catalyst were analysed by using different characterisation methods. The effects of the nickel-cobalt metal content and the reaction temperature on both the hydrogen production and the quality of the CNTs were investigated. The deposited carbonaceous products were characterised to analyse their external appearance, internal structure, oxidation stability and graphitisation degree. The results indicated that the catalyst containing 20% Ni and 30% Co showed the highest activity. When reaction temperature was 800 C, the instantaneous volume fraction of hydrogen was close to 43.5 vol% and the content of hydrogen in the gas product was close to 66.5 vol%. A few multi-walled CNTs having a small diameter and some CNTs with an open-topped structure were deposited on 10%Ni-40%Co/SBA-15 and 30%Ni-20%Co/SBA-15, respectively. Thermogravimetric analysis and Raman spectroscopic analysis indicated that all CNTs showed high oxidation stability and a high degree of graphitisation.

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“…Another peak located at 1,670 cm −1 was also detected for low-energy-deposited PLC films. According to previous studies, this peak might result from the combination of C=O stretching vibration peak around 1,700 cm −1 and the unpolymerized methacrylate peak at 1,640 cm −1 [46,93,94], which represented the oxidization of carbon.…”

Section: Bonding Evolution Governed By Ion Energymentioning

confidence: 81%

Ion energy-induced nanoclustering structure in a-C:H film for achieving robust superlubricity in vacuum

Chen

Zhang

et al. 2022

Friction

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Hydrogenated amorphous carbon (a-C:H) films are capable of providing excellent superlubricating properties, which have great potential serving as self-lubricating protective layer for mechanical systems in extreme working conditions. However, it is still a huge challenge to develop a-C:H films capable of achieving robust superlubricity state in vacuum. The main obstacle derives from the lack of knowledge on the influencing mechanism of deposition parameters on the films bonding structure and its relation to their self-lubrication performance. Aiming at finding the optimized deposition energy and revealing its influencing mechanism on superlubricity, a series of highly-hydrogenated a-C:H films were synthesized with appropriate ion energy, and systematic tribological experiments and structural characterization were conducted. The results highlight the pivotal role of ion energy on film composition, nanoclustering structure, and bonding state, which determine mechanical properties of highly-hydrogenated a-C:H films and surface passivation ability and hence their superlubricity performance in vacuum. The optimized superlubricity performance with the lowest friction coefficient of 0.006 coupled with the lowest wear rate emerges when the carbon ion energy is just beyond the penetration threshold of subplantation. The combined growth process of surface chemisorption and subsurface implantation is the key for a-C:H films to acquire stiff nanoclustering network and high volume of hydrogen incorporation, which enables a robust near-frictionless sliding surface. These findings can provide a guidance towards a more effective manipulation of self-lubricating a-C:H films for space application.

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Raman spectroscopic studies of stress-induced structure alteration in diamond-like carbon films

Cited by 24 publications

References 35 publications

Diamond Like Carbon Films Containing Si: Structure and Nonlinear Optical Properties

Diamond Like Carbon Films Containing Si: Structure and Nonlinear Optical Properties

Simultaneous production of hydrogen and carbon nanotubes from cracking of a waste cooking oil model compound over Ni‐Co / SBA ‐15 catalysts

Ion energy-induced nanoclustering structure in a-C:H film for achieving robust superlubricity in vacuum

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