Neutron-scattering studies of the structure of highly tetrahedral amorphous diamondlike carbon

Ph, Gaskell; Saeed, Adnan; Chieux, P.; McKenzie, David R.

doi:10.1103/physrevlett.67.1286

Cited by 172 publications

(59 citation statements)

References 12 publications

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“…We note here that in amorphous silicon films [22], there is a surprising difference in the ring statistics between the models prepared by 'splat cooling' and by atom-by-atom deposited network. The ratio of the sp 1 , sp 2 and sp 3 sites obtained are almost the same in our constructed structures. Only one extra atom with Z ¼ 4 appeared in the e1T100LQ film, compared to the e1T100L model.…”

Section: Resultssupporting

confidence: 55%

“…Coexistence of sp 2 and sp 3 atomic sites can produce non-crystalline structures with a wide range of gap in the density of states. A neutron diffraction study of an amorphous carbon (a-C) sample prepared by a filtered vacuum-arc method, proposed almost one hundred percent of sp 3 atomic configuration (ta-C) [1]. A measurement on another a-C sample [2] showed mostly sp 2 atomic arrangements.…”

Section: Introductionmentioning

confidence: 99%

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Time development during growth and relaxation of amorphous carbon films. Tight-binding molecular dynamics study

Koháry

Kugler

2002

Journal of Non-Crystalline Solids

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The growth of amorphous carbon (a-C) thin film on a [1 1 1] diamond surface has been studied by a tight-binding (TB) molecular dynamics (MD) technique. Six different three-dimensional networks were constructed with periodic boundary conditions in two dimensions. Time-dependent non-equilibrium growth was simulated with atom-by-atom deposition and it was described as in real experiments without an artificial model of energy dissipation. An additional seventh structure was constructed by a melt quenching procedure which is widely used in computer generations of amorphous networks. The final structures consist of over 100 atoms. Densities, radial distribution functions (RDFs), coordination numbers, bond angle distributions and ring statistics were analyzed. During relaxation the temperature in the amorphous film decreases with stretched-exponential function. The time dependence of bond length and bond angle deviations were also investigated. Ó

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Section: Resultssupporting

confidence: 55%

Section: Introductionmentioning

confidence: 99%

Time development during growth and relaxation of amorphous carbon films. Tight-binding molecular dynamics study

Koháry

Kugler

2002

Journal of Non-Crystalline Solids

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“…Extensive efforts in making diamond-like amorphous carbon [16][17][18] and tetrahedral amorphous carbon [19][20][21][22][23][24] using subplantation of incident ions have produced thin films with exceptional properties of high hardness, inertness, transparency and wide-bandgap semiconductivity for applications such as protective coatings for optical, electronic, mechanical, and biomedical components. However, these carbon films have less than 88% sp 3 -bonding, often contain a significant amount of hydrogenated carbon and nanocrystalline diamond, and are significantly different from a fully sp 3 -bonded bulk amorphous material.…”

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confidence: 99%

Amorphous Diamond: A High-Pressure Superhard Carbon Allotrope

et al. 2011

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Compressing glassy carbon above 40 GPa, we have observed a new carbon allotrope with a fully sp 3 -bonded amorphous structure and diamond-like strength. Synchrotron x-ray Raman spectroscopy revealed a continuous pressure-induced sp 2 -to-sp 3 bonding change, while x-ray diffraction confirmed the perseverance of non-crystallinity. The transition was reversible upon releasing pressure. Used as an indenter, the glassy carbon ball demonstrated exceptional strength by reaching 130 GPa with a confining pressure of 60 GPa. Such an extremely large stress difference of >70 GPa has never been observed in any material besides diamond, indicating the high hardness of this high-pressure carbon allotrope.

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“…Experimental investigations [10] and theoretical considerations of ta-C [9] have shown that it is appropriate to use prescribe an effective mass m* ≅ 0.9 m e for the valence electrons when calculating the specimen density from the plasmon peak position, where m e is the rest mass of the electron. However, for the sake of simplicity, the approximate densities in this paper are quoted using m* = m e .…”

Section: Lbnl-59023mentioning

confidence: 99%

Plasma biasing to control the growth conditions of diamond-like carbon

Anders¹,

Pasaja²,

Lim³

et al. 2007

Surface and Coatings Technology

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It is well known that the structure and properties of diamond-like carbon, and in particular the sp /sp ratio, can be controlled by the energy of the condensing carbon ions or atoms. In many practical cases, the energy of ions arriving at the surface of the growing film is determined by the bias applied to the substrate. The bias causes a sheath to form between substrate and plasma in which the potential difference between plasma potential and surface potential drops. In this contribution, we demonstrate that the same results can be obtained with grounded substrates by shifting the plasma potential. This "plasma biasing" (as opposed to "substrate biasing") is shown to work well with pulsed cathodic carbon arcs, resulting in tetrahedral amorphous carbon (ta-C) films that are comparable to the films obtained with the conventional substrate bias. To verify the plasma bias approach, ta-C films were deposited by both conventional and plasma bias and characterized by transmission electron microscopy (TEM) and electron energy loss spectrometry (EELS). Detailed data for comparison of these films are provided.

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Neutron-scattering studies of the structure of highly tetrahedral amorphous diamondlike carbon

Cited by 172 publications

References 12 publications

Time development during growth and relaxation of amorphous carbon films. Tight-binding molecular dynamics study

Time development during growth and relaxation of amorphous carbon films. Tight-binding molecular dynamics study

Amorphous Diamond: A High-Pressure Superhard Carbon Allotrope

Plasma biasing to control the growth conditions of diamond-like carbon

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