Radial distribution function of a new form of amorphous diamond shock induced from<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">C</mml:mi></mml:mrow><mml:mrow><mml:mn>60</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>fullerene

Hirai, Hisako; Tabira, Yasunori; Kondo, Ken‐ichi; Oikawa, Tetsuo; Ishizawa, Nobuo

doi:10.1103/physrevb.52.6162

Cited by 47 publications

(35 citation statements)

References 16 publications

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“…Indeed, in early experiments very hard and stiff materials were synthesised (stable under ambient conditions) by compressing fullerite under high pressure [6]. Subsequently, these phases have been characterised experimentally by determining their structural, mechanical, and optical properties [7,8,9,10,11,12,13,14,15] revealing a plethora of ordered (polymerised fullerenes) and disordered (amorphous) carbon phases (see [7] for a review).Based on electron diffraction experiments, shockcompressed fullerite [16], has been conjectured to be a new form of amorphous diamond exhibiting IRO [7]. Furthermore, it has been argued that the mechanical properties are determined by remnants of (partially) intact fullerene cages distinguishing these phases from tetrahedrally coordinated amorphous carbon (ta-C) produced by ion-beam techniques.…”

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Understanding of the Phase Transformation from Fullerite to Amorphous Carbon at the Microscopic Level

et al. 2005

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We have studied the shock-induced phase transition from fullerite to a dense amorphous carbon phase by tight-binding molecular dynamics. For increasing hydrostatic pressures P , the C60-cages are found to polymerise at P < 10 GPa, to break at P ∼ 40GPa and to slowly collapse further at P > 60 GPa. By contrast, in the presence of additional shear stresses, the cages are destroyed at much lower pressures (P < 30 GPa). We explain this fact in terms of a continuum model, the snapthrough instability of a spherical shell. Surprisingly, the relaxed high-density structures display no intermediate-range order. The extraordinary elastic properties of the molecular cage of C 60 have inspired many to speculate about new carbon modifications with extraordinary mechanical performance [5]. Indeed, in early experiments very hard and stiff materials were synthesised (stable under ambient conditions) by compressing fullerite under high pressure [6]. Subsequently, these phases have been characterised experimentally by determining their structural, mechanical, and optical properties [7,8,9,10,11,12,13,14,15] revealing a plethora of ordered (polymerised fullerenes) and disordered (amorphous) carbon phases (see [7] for a review).Based on electron diffraction experiments, shockcompressed fullerite [16], has been conjectured to be a new form of amorphous diamond exhibiting IRO [7]. Furthermore, it has been argued that the mechanical properties are determined by remnants of (partially) intact fullerene cages distinguishing these phases from tetrahedrally coordinated amorphous carbon (ta-C) produced by ion-beam techniques.However, up to now, conjectures concerning the structural properties are based on indirect information; neither the process of formation of such structures nor the nature of the proposed intermediate range order is understood microscopically. Pioneering molecular-dynamics (MD) simulations have shown that subjecting fullerite to high pressure and high temperatures may give rise to a dense amorphous phase [17]. However, the sample in [17] had to be compressed to very high densities (4.4 g/cm 3 at T = 2500K) corresponding to pressures exceeding 100GPa, far beyond any experimentally obtainable conditions. Empirically, the transition from fullerite to amorphous carbon occurs in the range of 10 − 30 GPa, depending on the speed of compression and on temperature (room temperature in [6] and approximately 2000K in shock experiments [7,16]). How may this contradiction be resolved? There are indications that shear stress may play a role in the destabilisation of the cages [6]. However, at present it is not known which microscopic processes cause the transition from fullerite to amorphous carbon. There is thus a pressing need for a theoretical understanding of the exact microscopic mechanisms occurring during this phase transition. To which extent is a macroscopic picture of a rapidly imploding spherical shell appropriate? Is shear important? How strong is the dependence of the final structural properties on the details of the comp...

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Understanding of the Phase Transformation from Fullerite to Amorphous Carbon at the Microscopic Level

et al. 2005

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“…This is further illustrated by the rapid amorphization of the present phase and the fact that static hot compression experiments 9,39,40 yielded only amorphous material with mixed sp 2 − sp 3 bond hybridization at the pressure and temperature comparable to our experiment. Interestingly, conventional shock wave loading of C 60 yielded amorphous diamondlike material 25 at lower loading and unloading rates. The ultrafast nature of loading to elevated pressure and temperature in our experiment and the loss of the crystallinity of the present phase at ambient conditions over a short period ͑compared to diamond͒ indicate that the present structure indeed represents an intermediate structural stage in the graphite-diamond transition.…”

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confidence: 99%

“…23,24 Conventional shock wave loading of C 60 fullerene yielded amorphous diamond. 25 The differences in heating and strain rates, porosity, starting materials, pressure-temperature conditions, and inherent kinetics for phase transitions may strongly affect the nature of the structures formed upon loading and upon recovery.In this work, we utilize laser-induced shock wave loading 26,27 at higher strain and heating rates and shorter loading durations to probe possible transient structures on the path of graphite-diamond transition. The starting materials were a mixture of graphite and copper powders ͑3:16 by mass͒.…”

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Novel crystalline carbon-cage structure synthesized from laser-driven shock wave loading of graphite

Luo

Tschauner

Tierney

et al. 2005

The Journal of Chemical Physics

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We report a novel crystalline carbon-cage structure synthesized from laser-driven shock wave loading of a graphite-copper mixture to about 14± 2 GPa and 1000± 200 K. Quite unexpectedly, it can be structurally related to an extremely compressed three-dimensional C 60 polymer with random displacement of C atoms around average positions equivalent to those of distorted C 60 cages. Thus, the present carbon-cage structure represents a structural crossing point between graphite interlayer bridging and C 60 polymerization as the two ways of forming diamond from two-dimensional and molecular carbon. Understanding the graphite-diamond transition mechanisms including transitory or intermediate phases may open windows for a more efficient synthesis of diamond. The graphite-diamond transition is also interesting by itself as a paradigm of reconstructive transitions involving changes in coordination, bonding and dimensionality, and for its possible relations with other transition routes to diamond from, for instance, C 60 polymers. However, the detailed mechanisms still remain unsettled despite considerable experimental and theoretical efforts motivated by the technological and scientific significance.Carbon is a complicated system 1 rich in polymorphs due to its ability to form sp-, sp 2 -, and sp 3 -hybridized C-C bonds including molecular phases such as buckyballs and buckytubes, the two-dimensional ͑2D͒ graphite, and threedimensional ͑3D͒ tetrahedral network of diamond. C 60 polymers, 2-5 carbyne, 6 and hypothetical cage structures such as carbon zeolites 7 establish intermediate phases intriguing for their structures and properties. The phase diagram and other high-pressure properties of C 60 have been investigated extensively using static techniques. 4,[8][9][10][11][12][13][14][15] The transitions of graphite and buckyballs to diamond involve major reconstruction of bonding and coordination, and thus are loadingrate-dependent processes. Dynamic experiments such as shock waves may be advantageous for revealing the transition mechanisms by metastable recovery of transient structures formed upon ultrafast loading. We have demonstrated for silica ͑another paradigm system͒ that a transient structure intermediate between tetrahedrally and octahedrally coordinated phases forms upon shock wave loading of quartz and coesite. 16 Diamond was synthesized by conventional shock wave ͑explosives or gas guns͒ loading of graphite alone or graphite-copper powder mixture to about 20 GPa and above. [17][18][19][20] Recent explosive-driven shock wave loading of pyrolytic graphite to about 15 GPa yielded several carbon allotropes including carbyne, a diamondlike phase and possibly fullerene. 21 It is worth noting that C 60 fullerene synthesis was pioneered by vaporizing graphite using lasers. 22 Naturally occurring fullerenes in meteorites and sediments were inferred to have formed during terrestrial impact. 23,24 Conventional shock wave loading of C 60 fullerene yielded amorphous diamond. 25 The differences in heating and strain rates, po...

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“…The formation of covalent bonds makes the new phases very stable. Hirai et al [12] reported amorphous diamond prepared from C 60 by shock compression. Based on the indirect scratching observations [13] and measurements made by time-resolved acoustic microscopy [ 14], Blank et aL [9] postulated that superhard and ultrahard phases could be synthesized from C 60 .…”

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confidence: 99%

Acoustic Microscopy and Surface Brillouin Scattering of Amorphous Carbon Pressure-Synthesized From C₆₀

Zinin¹,

Manghnani²,

Tkachev³

et al. 2001

MRS Proc.

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Here, we report successful measurements by surface Brillouin scattering (SBS) and scanning acoustic microscopy (SAM) of the elastic properties of small specimens of amorphous carbon obtained from C 60 under high pressure and temperature. The superhard phases of amorphous carbon were synthesized from C 60 at pressure 13 -13.5 GPa and temperature 800-900 0 C. Two types of acoustic waves have been detected by SBS in superhard samples: surface Rayleigh wave and bulk longitudinal wave. The longitudinal velocity (VL) in the hardest sample is slightly lower than longitudinal wave velocity in diamond in [110] direction. Simultaneous measurements of the Rayleigh and longitudinal wave velocities make it possible to determine shear and bulk elastic moduli of the specimens. Obtained elastic properties for amorphous carbon synthesized under pressure 13.5 GPa and temperature 900'C are close to those for diamond, indicating that bonds among amorphous carbon network are diamond bonding dominated.

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Radial distribution function of a new form of amorphous diamond shock induced fromC60fullerene

Cited by 47 publications

References 16 publications

Understanding of the Phase Transformation from Fullerite to Amorphous Carbon at the Microscopic Level

Understanding of the Phase Transformation from Fullerite to Amorphous Carbon at the Microscopic Level

Novel crystalline carbon-cage structure synthesized from laser-driven shock wave loading of graphite

Acoustic Microscopy and Surface Brillouin Scattering of Amorphous Carbon Pressure-Synthesized From C₆₀

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Radial distribution function of a new form of amorphous diamond shock induced fromC60fullerene

Cited by 47 publications

References 16 publications

Understanding of the Phase Transformation from Fullerite to Amorphous Carbon at the Microscopic Level

Understanding of the Phase Transformation from Fullerite to Amorphous Carbon at the Microscopic Level

Novel crystalline carbon-cage structure synthesized from laser-driven shock wave loading of graphite

Acoustic Microscopy and Surface Brillouin Scattering of Amorphous Carbon Pressure-Synthesized From C60

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Acoustic Microscopy and Surface Brillouin Scattering of Amorphous Carbon Pressure-Synthesized From C₆₀