Carbon-hydrogen bonding in near-frictionless carbon

Johnson, Jacqueline A.; Woodford, John; Rajput, Deepak; Kolesnikov, A. I.; Schleuter, J. A.; Eryilmaz, O. L.; Erdemir, Ali

doi:10.1063/1.2990757

Cited by 12 publications

(7 citation statements)

References 20 publications

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“…The presence of a flat mode at 360 meV in Fig. 5c confirms that the scattering at 170 meV arises from the C-H bending mode 44,45 . Figure 5d shows the scattering from liquid CYTOP-M at room temperature, where the 170 meV C-H bending mode in solidified CYTOP-M moves to 150 meV.…”

Section: Resultssupporting

confidence: 60%

“…4a), suggesting that the modes in both compounds do not have a magnetic origin. Since our FeSn and CoSn samples are glued on the aluminum plates by CYTOP-M which is an amorphous fluoropolymer but contains one hydrogen to facilitate bonding to metal surface 36,43 , the hydrogenated amorphous carbon films formed between sample and aluminum plates should have C-H bending and stretching vibrational modes occurring around 150-180 meV and 350-380 meV, respectively 44,45 . Indeed, a scan with incident neutron beam energy of 500 mV reveals the presence of a flat mode around 350-380 meV (Fig.…”

Section: Resultsmentioning

confidence: 99%

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Spin excitations in metallic kagome lattice FeSn and CoSn

Xie

Chen

et al. 2021

Commun Phys

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In two-dimensional (2D) metallic kagome lattice materials, destructive interference of electronic hopping pathways around the kagome bracket can produce nearly localized electrons, and thus electronic bands that are flat in momentum space. When ferromagnetic order breaks the degeneracy of the electronic bands and splits them into the spin-up majority and spin-down minority electronic bands, quasiparticle excitations between the spin-up and spin-down flat bands should form a narrow localized spin-excitation Stoner continuum coexisting with well-defined spin waves in the long wavelengths. Here we report inelastic neutron scattering studies of spin excitations in 2D metallic kagome lattice antiferromagnetic FeSn and paramagnetic CoSn, where angle resolved photoemission spectroscopy experiments found spin-polarized and nonpolarized flat bands, respectively, below the Fermi level. Our measurements on FeSn and CoSn reveal well-defined spin waves extending above 140 meV and correlated paramagnetic scattering around Γ point below 90 meV, respectively. In addition, we observed non-dispersive excitations at ~170 meV and ~360 meV arising mostly from hydrocarbon scattering of the CYTOP-M used to glue the samples to aluminum holder. Therefore, our results established the evolution of spin excitations in FeSn and CoSn, and identified anomalous flat modes overlooked by the neutron scattering community for many years.

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Section: Resultssupporting

confidence: 60%

Section: Resultsmentioning

confidence: 99%

Spin excitations in metallic kagome lattice FeSn and CoSn

Xie

Chen

et al. 2021

Commun Phys

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“…[Molecular hydrogen termination was a long-held hypothesis. However, recent studies suggest that only atomic hydrogen coverage of NFC surfaces is present (83).] Erdemir et al (82) believe that the hydrogen atoms lose their electron to the outer shell of the carbon atoms, leaving the positively charged hydrogen nucleus exposed.…”

Section: Extrinsic Solid Lubricantsmentioning

confidence: 99%

Chameleon Coatings: Adaptive Surfaces to Reduce Friction and Wear in Extreme Environments

Muratore

Voevodin

2009

Annu. Rev. Mater. Res.

188

104

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Adaptive nanocomposite coating materials that automatically and reversibly adjust their surface composition and morphology via multiple mechanisms are a promising development for the reduction of friction and wear over broad ranges of ambient conditions encountered in aerospace applications, such as cycling of temperature and atmospheric composition. Materials selection for these composites is based on extensive study of interactions occurring between solid lubricants and their surroundings, especially with novel in situ surface characterization techniques used to identify adaptive behavior on size scales ranging from 10 −10 to 10 −4 m. Recent insights on operative solid-lubricant mechanisms and their dependency upon the ambient environment are reviewed as a basis for a discussion of the state of the art in solid-lubricant materials. 297 Click here for quick links to Annual Reviews content online, including: • Other articles in this volume • Top cited articles • Top downloaded articles • Our comprehensive search Further ANNUAL REVIEWS Tribology: the study of surfaces in relative motion, from the Greek word tribos, meaning rubbing Friction coefficient: the ratio of tangential force to applied normal force, or the ratio of shear strength to pressure if both forces are divided by contact area Abrasive wear: the plowing away of softer material by harder particles at contact interfaces Adhesive wear: asperities from both surfaces in contact adhere, and material from the softer surface is sheared away as the counterface moves Fatigue wear: the removal of material due to crack growth and propagation over repeated load cycles Wear rate: the rate of material loss from a surface due to sliding contact, often reported in units of volume lost per unit sliding distance per unit of applied normal force (e.g., mm 3 m −1 N −1) FUNDAMENTALS OF SOLID LUBRICATION IN DIVERSE ENVIRONMENTS A spray of liquid lubricant from a can available at the hardware store solves most familiar friction and wear problems on Earth under ordinary conditions of ambient pressure, humidity, and temperature. When any one of those operating parameters reaches the limits of advanced engineering materials, however, the availability of suitable lubricants is diminished significantly. Moreover, if operation throughout a broad range of any one of these environmental factors is desired, the number of choices becomes exactly zero; tribologists have found that no single surface can lubricate effectively outside a narrow span of ambient humidity or temperature (1-3). In fact, one of the primary technological barriers for the development of new jet engines for sustained highmach-number (>5) flights and other key aerospace advances is the ability to lubricate mechanical assemblies from ambient temperature to >1000 • C. Only recently have discoveries of self-adaptive mechanisms and subsequent developments in tribological coatings, made possible with modern instrumentation and pioneering efforts to observe phenomena at atomic through microscopic size scales at contact ...

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“…Diamond-like carbon (DLC) containing a large proportion of combined sp 3 /sp 2 -hybrid bonds has extreme properties similar to diamonds [1][2][3][4][5]. It is possible to prepare DLC films for several important applications in the fields of mechanical manufacturing, solar energy devices, electricity devices, and so forth, owing to their excellent properties, including high hardness, high thermal conductivity, high electrical resistivity, low infrared (IR) absorption, transparency to visible light, hydrophobic behavior, and chemical inertness [6][7][8][9][10][11].…”

Section: Introductionmentioning

confidence: 99%

Fabrication of High Transparency Diamond-Like Carbon Film Coating on D263T Glass at Room Temperature as an Antireflection Layer

Lin

Chang

2013

International Journal of Photoenergy

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This study intends to deposit high transmittance diamond-like carbon (DLC) thin films on D263T glass substrate at room temperature via a diamond powder target using the radio frequency (RF) magnetron sputtering technique. Moreover, various process parameters were used to tune the properties of the thin films by using the Taguchi method. Experimental results show that the content of sp3bonded carbon decreases in accordance with the effect of the substrate temperature. In addition, the hardness of all as-deposited single-layer DLC films ranges from 13.2 to 22.5 GPa, and the RMS surface roughness was improved significantly with the decrease in sputtering pressure. The water repellent of the deposited DLC films improved significantly with the increase of the sp3content, and its contact angle was larger than that of the noncoated one by 1.45 times. Furthermore, the refraction index (n) of all as-deposited DLC films ranges from 1.95 to 2.1 atλ= 600 nm. These results demonstrate that the thickness increased as the reflectance increased. DLC film under an RF power of 150 W possesses high transmissive ability (>81%) and low average reflectance ability (<9.5%) in the visible wavelengths (atλ= 400–700 nm).

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Carbon-hydrogen bonding in near-frictionless carbon

Cited by 12 publications

References 20 publications

Spin excitations in metallic kagome lattice FeSn and CoSn

Spin excitations in metallic kagome lattice FeSn and CoSn

Chameleon Coatings: Adaptive Surfaces to Reduce Friction and Wear in Extreme Environments

Fabrication of High Transparency Diamond-Like Carbon Film Coating on D263T Glass at Room Temperature as an Antireflection Layer

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