pith. sign in

arxiv: 1907.09033 · v1 · pith:2LCEN6CQnew · submitted 2019-07-21 · ❄️ cond-mat.mtrl-sci

Towards a better understanding of the structure of diamano\"ids and diamano\"id/graphene hybrids

Fabrice Piazza , Marc Monthioux , Pascal Puech , Iann C. Gerber This is my paper

Pith reviewed 2026-05-24 18:22 UTC · model grok-4.3

classification ❄️ cond-mat.mtrl-sci
keywords diamanoidsgraphene hybridsRaman T peaksp2-sp3 conversiontwisted coherent domainsDFT calculationslow-energy electron diffraction
0
0 comments X

The pith

DFT calculations show the Raman T peak originates from a mixed sp2-sp3 layer between a hydrogenated sp3 surface and underlying graphene in partially converted hybrids.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper investigates the atomic arrangement in diamanoids and diamanoid-graphene hybrids produced by partial hot-filament conversion of few-layer graphene. Low-energy electron diffraction reveals pairs of twisted coherent domains that form to relieve stress when conversion stops short of full sp3 sheets. Raman data combined with DFT calculations tie the previously unexplained T peak to vibrations within a mixed sp2-sp3 carbon layer that sits between the hydrogenated sp3 surface and the remaining graphene sheet below. A reader would care because the electronic and mechanical behavior of these new carbon nanoforms hinges on exactly where and how the sp2 and sp3 regions meet.

Core claim

Partial sp2-C to sp3-C conversion generates couples of twisted, superimposed coherent domains (TCD), supposedly because of stress relaxation, which are evidenced by electron diffraction and Raman spectroscopy. TCDs come with the occurrence of a twisted bilayer graphene feature located at the interface between the upper diamanoid domain and the non-converted graphenic domain underneath, as evidenced by a specific Raman signature consistent with the literature. DFT calculations show that the up-to-now poorly understood Raman T peak originates from a sp2-C-sp3-C mixt layer located between a highly hydrogenated sp3-C surface layer and an underneath graphene layer.

What carries the argument

The twisted coherent domains (TCD) produced by stress relaxation during partial conversion, together with the sp2-C-sp3-C mixed interface layer whose vibrations DFT assigns to the Raman T peak.

If this is right

  • Twisted coherent domains appear in pairs to accommodate stress when conversion remains incomplete.
  • A twisted bilayer graphene region forms at the boundary between each converted domain and the unconverted graphene beneath it.
  • The T peak intensity tracks the presence and extent of the mixed sp2-sp3 interface layer.
  • Electron diffraction patterns directly reflect the twist between the superimposed coherent domains.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • Varying the starting layer count or conversion time could systematically change the twist angles and thereby tune the hybrid's electronic band structure.
  • The same mixed-layer mechanism may operate at sp2-sp3 boundaries created by other low-pressure carbon conversion routes.
  • Imaging the interface twist angle in real space could test whether the Raman T peak strength scales with the mixed-layer area predicted by the model.

Load-bearing premise

The Raman signatures and low-energy electron diffraction patterns arise specifically from the proposed twisted coherent domains and the mixed sp2-sp3 interface layer rather than from other stacking faults, defects, or measurement artifacts in the partially converted material.

What would settle it

High-resolution imaging of a partially converted sample that shows neither twisted domains nor a mixed sp2-sp3 layer yet still exhibits the Raman T peak would falsify the proposed structural origin.

Figures

Figures reproduced from arXiv: 1907.09033 by Fabrice Piazza, Iann C. Gerber, Marc Monthioux, Pascal Puech.

Figure 1
Figure 1. Figure 1: FIG. 1. (a) [PITH_FULL_IMAGE:figures/full_fig_p006_1.png] view at source ↗
Figure 3
Figure 3. Figure 3: FIG. 3 [PITH_FULL_IMAGE:figures/full_fig_p008_3.png] view at source ↗
Figure 4
Figure 4. Figure 4: FIG. 4. (a) [PITH_FULL_IMAGE:figures/full_fig_p010_4.png] view at source ↗
Figure 5
Figure 5. Figure 5: FIG. 5. (a) [PITH_FULL_IMAGE:figures/full_fig_p012_5.png] view at source ↗
read the original abstract

Hot-filament process was recently employed to convert, totally or partially, few-layer graphene (FLG) with Bernal stacking into crystalline sp$^3$-C sheets at low pressure. Those materials constitute new synthetic carbon nanoforms. The result reported earlier relies on Raman spectroscopy and Fourier transform infrared microscopy. As soon as the number of graphene layers in the starting FLG is higher than 2-3, the sp$^2$-C to sp$^3$-C conversion tends to be partial only. We hereby report new evidences confirming the sp$^2$-C to sp$^3$-C conversion from electron diffraction at low energy,Raman spectroscopy and Density Functional Theory (DFT) calculations. Partial sp$^2$-C to sp$^3$-C conversion generates couples of twisted, superimposed coherent domains (TCD), supposedly because of stress relaxation, which are evidenced by electron diffraction and Raman spectroscopy. TCDs come with the occurrence of a twisted bilayer graphene feature located at the interface between the upper diamano\"id domain and the non-converted graphenic domain underneath, as evidenced by a specific Raman signature consistent with the literature. DFT calculations show that the up-to-now poorly understood Raman T peak originates from a sp$^2$-C-sp$^3$-C mixt layer located between a highly hydrogenated sp$^3$-C surface layer and an underneath graphene layer.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

2 major / 2 minor

Summary. The manuscript examines partial hot-filament conversion of few-layer Bernal graphene into diamanoid/graphene hybrids. It reports low-energy electron diffraction evidence for twisted coherent domains (TCDs) arising from stress relaxation, a Raman signature consistent with twisted bilayer graphene at the diamanoid-graphene interface, and DFT calculations that assign the Raman T peak to vibrational modes of a mixed sp2-sp3 layer located between a hydrogenated sp3 surface and an underlying graphene sheet.

Significance. If the DFT assignment is shown to be unique to the proposed interface, the work would clarify the atomic structure of these partially converted carbon nanoforms and strengthen the interpretation of their Raman spectra, which are central to characterizing the new materials. The multi-technique approach (diffraction + Raman + computation) is appropriate for the problem.

major comments (2)
  1. [DFT calculations section] The central DFT claim (that the T peak arises specifically from the sp2-C-sp3-C mixed layer) is load-bearing for the structural model. The manuscript must demonstrate that plausible alternative interfaces—different twist angles, stacking faults, or hydrogenation gradients that can also form during partial conversion—do not produce Raman intensity at the observed T frequency. No such control calculations are described.
  2. [Electron diffraction results] § on electron diffraction: the assignment of the observed patterns to twisted coherent domains (TCDs) rather than other stacking faults or measurement artifacts requires quantitative comparison of simulated diffraction intensities for the proposed TCD geometry versus competing defect models.
minor comments (2)
  1. [Abstract] The abstract contains the typographical error 'mixt layer' (should be 'mixed layer') and inconsistent quotation marks around 'diamanoïd'.
  2. [Raman spectroscopy section] Notation for the Raman T peak and its assignment should be cross-referenced explicitly to the DFT vibrational-mode table or figure.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the constructive comments on our manuscript. We address the two major comments point-by-point below and will revise the manuscript to incorporate additional calculations where feasible.

read point-by-point responses

  1. Referee: [DFT calculations section] The central DFT claim (that the T peak arises specifically from the sp2-C-sp3-C mixed layer) is load-bearing for the structural model. The manuscript must demonstrate that plausible alternative interfaces—different twist angles, stacking faults, or hydrogenation gradients that can also form during partial conversion—do not produce Raman intensity at the observed T frequency. No such control calculations are described.

    Authors: We agree that the uniqueness of the T-peak assignment would be strengthened by explicit control calculations on alternative interfaces. The current DFT section focuses on the interface model consistent with our experimental observations (twisted domains and partial conversion). In the revised manuscript we will add a set of control calculations exploring different twist angles, stacking faults, and hydrogenation gradients to confirm that they do not produce intensity at the observed T frequency. These results will be presented alongside the existing calculations. revision: yes

  2. Referee: [Electron diffraction results] § on electron diffraction: the assignment of the observed patterns to twisted coherent domains (TCDs) rather than other stacking faults or measurement artifacts requires quantitative comparison of simulated diffraction intensities for the proposed TCD geometry versus competing defect models.

    Authors: We acknowledge that a quantitative intensity comparison would make the TCD assignment more robust. The experimental patterns are interpreted as TCDs on the basis of the observed spot splitting and the known stress-relaxation mechanism during partial conversion. In the revised manuscript we will include simulated diffraction patterns for the proposed TCD geometry together with quantitative intensity comparisons against competing models (alternative stacking faults and possible measurement artifacts) to demonstrate that the TCD model provides the best match. revision: yes

Circularity Check

0 steps flagged

No significant circularity detected

full rationale

The paper's central claim rests on new low-energy electron diffraction patterns, Raman spectra, and DFT calculations that assign the T peak to a proposed sp2-sp3 mixed interface layer. No equations, fitted parameters presented as predictions, or self-definitional steps appear in the provided text. References to 'consistent with the literature' for twisted bilayer signatures are standard external support rather than load-bearing self-citations that reduce the result to the paper's own inputs. The derivation chain is observational plus computational interpretation and remains self-contained against external benchmarks.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

Abstract-only review; no explicit free parameters, axioms, or invented entities are stated. The structural model (TCDs, mixed interface layer) is treated as interpretive rather than derived from first principles.

pith-pipeline@v0.9.0 · 5792 in / 1166 out tokens · 17151 ms · 2026-05-24T18:22:35.045112+00:00 · methodology

discussion (0)

Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.

Reference graph

Works this paper leans on

30 extracted references · 30 canonical work pages

  1. [1]

    Diamond -Like C2H Nanolayer, Diamane: Simulation of the Structure and Properties., J Exp Theor Phys Lett (2009) 90, 134-138

    Chernozatonskii L.A.; Sorokin P.B.; Kvashnin A.; Kvashnin D.G. Diamond -Like C2H Nanolayer, Diamane: Simulation of the Structure and Properties., J Exp Theor Phys Lett (2009) 90, 134-138

    work page 2009

  2. [2]

    Low Temperature, Pressureless sp2 to sp3 Transformation of Ultrathin, Crystalline Carbon Films., Carbon (2019) 145, 10-22

    Piazza F.; Gough K.; Monthioux M.; Puech P.; Gerber I.; Wiens R.; Paredes G.; Ozoria C. Low Temperature, Pressureless sp2 to sp3 Transformation of Ultrathin, Crystalline Carbon Films., Carbon (2019) 145, 10-22

    work page 2019

  3. [3]

    Influence of Size Effect on the Electronic and Elastic Properties of Diamond Films with Nanometer Thickness., J Phys Chem C (2011) 115,132-136

    Chernozatonskii L.A.; Sorokin P.B.; Kuzubov A.A.; Sorokin B.P.; Kvashnin A.G.; Kvashnin D.G.; et al. Influence of Size Effect on the Electronic and Elastic Properties of Diamond Films with Nanometer Thickness., J Phys Chem C (2011) 115,132-136

    work page 2011

  4. [4]

    Determination of ultrathin diamond films by Raman spectroscopy., Phys Status Solidi B (2012) 249, 1550-1554

    Chernozatonskii L.A.; Mavrin B.N.; Sorokin P.B. Determination of ultrathin diamond films by Raman spectroscopy., Phys Status Solidi B (2012) 249, 1550-1554

    work page 2012

  5. [5]

    Personal perspectives on graphene: New graphene-related materials on the horizon., Mat Res Soc Bulletin (2012) 37, 1314-1318

    Ruoff R.S. Personal perspectives on graphene: New graphene-related materials on the horizon., Mat Res Soc Bulletin (2012) 37, 1314-1318

    work page 2012

  6. [6]

    Two -Level Quantum Systems in Two -Dimensional Materials for Single Photon Emission., Nano Lett (2019) 19(1) 408-414

    Gupta S.; Yang J.H.; Yakobson B.I. Two -Level Quantum Systems in Two -Dimensional Materials for Single Photon Emission., Nano Lett (2019) 19(1) 408-414

    work page 2019

  7. [7]

    Neumaier D

    Fiori G.; Bonaccorso F.; Iannaccone G.; Palacios T. ; Neumaier D. ; Seabaugh A.; Banerjee S.K.; Colombo L.; Electronics based on two-dimensional materials., Nature Nanotechnology (2014) 9(10) 768-779

    work page 2014

  8. [8]

    Interlayer carbon bond formation induced by hydrogen adsorption in few-layer supported graphene., Phys Rev Lett (2013) 111, 085503-1-058503-5

    Rajasekaran S.; Abild-Pedersen F.; Ogasawara H.; Nilsson A.; Kaya S. Interlayer carbon bond formation induced by hydrogen adsorption in few-layer supported graphene., Phys Rev Lett (2013) 111, 085503-1-058503-5

    work page 2013

  9. [9]

    Diamond-like amorphous carbon., Mater Sci Eng R (2002) 37, 129-281

    Robertson J. Diamond-like amorphous carbon., Mater Sci Eng R (2002) 37, 129-281

    work page 2002

  10. [10]

    Hard -hydrogenated tetrahedral amorphous carbon films by distributed electron cyclotron resonance plasma., Int J Refract Met Hard Mater (2006) 24, 39-48

    Piazza F. Hard -hydrogenated tetrahedral amorphous carbon films by distributed electron cyclotron resonance plasma., Int J Refract Met Hard Mater (2006) 24, 39-48

    work page 2006

  11. [11]

    Room temperature compression -induced diamondization of few -layer graphene., Adv Mater (2011) 23, 3014-3017

    Barboza A.P.M.; Guimaraes M.H.D.; Massote D.V.P.; Campos L.C.; Barbosa Neto N.M.; Cancado L.G.; et al. Room temperature compression -induced diamondization of few -layer graphene., Adv Mater (2011) 23, 3014-3017. Piazza et al. 20

    work page 2011

  12. [12]

    Raman evidence for pressure-induced formation of diamondene., Nat Comm (2017) 8 (1) 96 (9 pages)

    Martins L.G.P.; Matos M.J.S.; Paschoal A.R.; Freire P.T.C.; Andrade N.F.; Aguiar A.L.; Kong J.; Neves B.R.A.; de Oliveira A.B.; Mazzoni M.S.C.; Filho A.G.S.; Cancado L.G. Raman evidence for pressure-induced formation of diamondene., Nat Comm (2017) 8 (1) 96 (9 pages)

    work page 2017

  13. [13]

    Ultrahard carbon film from epitaxial two-layer graphene., Nature Nanotechnology (2018) 13, 133- 138

    Gao Y.; Cao T.; Cellini F.; Berger C.; de Heer W.A.; Tosatii E.; Riedo E.; Bongiorno A. Ultrahard carbon film from epitaxial two-layer graphene., Nature Nanotechnology (2018) 13, 133- 138

    work page 2018

  14. [14]

    Chemically Induced Transformation of CVD -Grown Bilayer Graphene into Single Layer Diamond

    Bakharev P.V.; Huang M.; Saxena M.; Lee S.W.; Jo o S.H; Park S.O.; Dong J.; Camacho - Mojica D.; Jin S.; Kwon Y.; Biswal M.; Ding F.; Kwak S.K.; Lee Z.; Ruoff R.S. Chemically Induced Transformation of CVD -Grown Bilayer Graphene into Single Layer Diamond. (2019) Arxiv.org/abs/1901.02131v1

    work page arXiv 2019

  15. [15]

    A direct transfer of layer-area graphene

    Regan W, Alem N, Aleman B, Geng B, Girit C, Masareti L et al. A direct transfer of layer-area graphene. Appl Phys Lett 2010;96:113102-1-113102-3

    work page 2010

  16. [16]

    Carbon nanotubes coated with diamond nanocrystals and silicon carbide by hot -filament chemical vapor deposition below 200 C substrate temperature

    Piazza F, Morell G, Beltran -Huarac J, Paredes G, Ahmadi M, Guinel M. Carbon nanotubes coated with diamond nanocrystals and silicon carbide by hot -filament chemical vapor deposition below 200 C substrate temperature. Carbon 2014;75, 113-123

    work page 2014

  17. [17]

    Neverov, V. S. (2017). XaNSoNS: GPU-accelerated simulator of diffraction patterns of nanoparticles. SoftwareX, 6, 63-68

    work page 2017

  18. [18]

    Ab initio molecular dynamics for liquid metals

    Kresse G, Hafner J. Ab initio molecular dynamics for liquid metals. Phys Rev B 1993;47:558- 561

    work page 1993

  19. [19]

    Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set

    Kresse G, Furthmüller J. Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set. Phys Rev B 1996; 54: 11169-11186

    work page 1996

  20. [20]

    Projector augmented-wave method

    Blöchl PE. Projector augmented-wave method. Phys Rev B 1994;50:17953-17979

    work page 1994

  21. [21]

    From ultrasoft pseudopotentials to the projector augmented-wave method

    Kresse G, Joubert D. From ultrasoft pseudopotentials to the projector augmented-wave method. Phys Rev B 1999; 59: 1758-1775

    work page 1999

  22. [22]

    Generalized Gradient Approximation Made Simple

    Perdew JP, Burke K, Ernzerhof M. Generalized Gradient Approximation Made Simple. Phys Rev Lett 1996;77:3865-3668

    work page 1996

  23. [23]

    A consistent and accurate ab initio parametrization of density functional dispersion correction (DFT-D) for the 94 elements H-Pu

    Grimme S, Antony J, Ehrlich S, Krieg H. A consistent and accurate ab initio parametrization of density functional dispersion correction (DFT-D) for the 94 elements H-Pu. J Chem Phys 2010;132:154104-1-154104-1-19

    work page 2010

  24. [24]

    Piazza et al

    Togo A, Tanaka I, First principles phonon calculations in materials science, Scripta Material 2015;108: 1–5. Piazza et al. 21

    work page 2015

  25. [25]

    2018 International Centre for Diffraction Data

    work page 2018

  26. [26]

    Structural and electron diffraction scaling of twisted graphene bilayers, J Mechanics Phys Solids 2018; 112: 225-238

    Zhang K, Tadmor Ellad B. Structural and electron diffraction scaling of twisted graphene bilayers, J Mechanics Phys Solids 2018; 112: 225-238

    work page 2018

  27. [27]

    Atomic and electronic reconstruction at the van der Waals interface in twisted bilayer graphene, Nature Materials 2019; https://doi.org/10.1038/s41563-019-0346-z

    Yoo H, Engelke R, Carr S, Fang S, Zhang K, Cazeaux P et al. Atomic and electronic reconstruction at the van der Waals interface in twisted bilayer graphene, Nature Materials 2019; https://doi.org/10.1038/s41563-019-0346-z

    work page doi:10.1038/s41563-019-0346-z 2019

  28. [28]

    Intralayer and interlayer electron -phonon interactions in twisted graphene heterostructures, Nature Communications 2018, 9:1221; DOI:10.1038/s41467-018-03479-3

    Eliel GSN, Moutinho MVO, Gadelha AC, Righi A, Campos LC, Ribeiro HB. Intralayer and interlayer electron -phonon interactions in twisted graphene heterostructures, Nature Communications 2018, 9:1221; DOI:10.1038/s41467-018-03479-3

    work page doi:10.1038/s41467-018-03479-3 2018

  29. [29]

    Preparation and properties of highly tetrahedral hydrogenated amorphous carbon, Phys Rev B (1996); 53: 1594 - 1608

    Weiler M, Sattel S, Giessen T, Jung K, Ehrhardt, Veerasamy VS, Robertson J. Preparation and properties of highly tetrahedral hydrogenated amorphous carbon, Phys Rev B (1996); 53: 1594 - 1608

    work page 1996

  30. [30]

    Graphite under pressure: Equation of state and first-order Raman modes, Phys

    Hanfland M., Beister H., Syassen K. Graphite under pressure: Equation of state and first-order Raman modes, Phys. Rev. B (1989); 39 (17), 12598-12603

    work page 1989