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Synthesis of diamond-like phase from graphite by ultrafast laser driven dynamical compression.

Maia FC, Samad RE, Bettini J, Freitas RO, Vieira Junior ND, Souza-Neto NM - Sci Rep (2015)

Bottom Line: Here, by exposing polycrystalline graphite to 25 fs laser pulses at 4 J/cm(2) fluence under standard air atmosphere, we demonstrated the synthesis of translucent micrometer-sized structures carrying diamond-like and onion-like carbon phases.Texturized domains of the diamond phase were also identified.Concerning different synthesized carbon forms, pulse superposition and singularities of the thermodynamical process, we pinpoint the synthesis mechanism by the laser-induced subsequent products energetically evolving to attain the diamond-like phase.

View Article: PubMed Central - PubMed

Affiliation: Laboratório Nacional de Luz Síncrotron (LNLS), Campinas, São Paulo 13083-970, Brazil.

ABSTRACT
Rapid variations of the environmental energy caused by ultrashort laser pulses have induced phase transitions in carbon allotropes, therefore bringing the promise of revealing new carbon phases. Here, by exposing polycrystalline graphite to 25 fs laser pulses at 4 J/cm(2) fluence under standard air atmosphere, we demonstrated the synthesis of translucent micrometer-sized structures carrying diamond-like and onion-like carbon phases. Texturized domains of the diamond phase were also identified. Concerning different synthesized carbon forms, pulse superposition and singularities of the thermodynamical process, we pinpoint the synthesis mechanism by the laser-induced subsequent products energetically evolving to attain the diamond-like phase.

No MeSH data available.


Related in: MedlinePlus

High Resolution Electron Diffraction analysis of the diamond-like phase.SADs of the (a) laser created structures, and (b) its graphite precursor; (c) HREM micrograph of the laser created structure with the characteristic 0.205 nm d-spacing of the diamond phase evidenced by the zoom of a small area shown in the bottom inset; the upper inset shows the Fourier Transform of the whole image; (d) exhibits the corresponding electron diffraction peaks as a function of the inverse of the d-spacing for the polycrystalline graphite (PG, gray spectrum) and diamond-like phase (blue spectrum).
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f2: High Resolution Electron Diffraction analysis of the diamond-like phase.SADs of the (a) laser created structures, and (b) its graphite precursor; (c) HREM micrograph of the laser created structure with the characteristic 0.205 nm d-spacing of the diamond phase evidenced by the zoom of a small area shown in the bottom inset; the upper inset shows the Fourier Transform of the whole image; (d) exhibits the corresponding electron diffraction peaks as a function of the inverse of the d-spacing for the polycrystalline graphite (PG, gray spectrum) and diamond-like phase (blue spectrum).

Mentions: The Raman spectrum of the laser-created structure transferred to a Cu grating (Fig. 1e) shows an expressively pronounced G-band at 1580 cm−1. While this band nearly dominates the spectrum, less intense vibrational resonances similar to the ones for the laser modified surface are also present. The dominance of the G-band closely resembles the Raman spectrum of HOPG26, therefore, indicating that the laser shockwaves induced reconstruction of the disordered arrangement of the pristine graphite into a more ordered graphitic phase. However, Selected Area of Diffraction (SAD) analysis of crystallites at multiple regions of this laser created structure (Fig. 1f) turned out being rather different from graphite, as can be noted in Fig. 2a (laser created particle) and 2b (polycrystalline graphite precursor). By assessing the related diffraction peaks plotted as a function of the inverse of the d-spacing (Fig. 2d), the laser induced changes are corroborated by the clear absence of the 0.338 nm interlayer distance – a signature of graphitic phase – in the created structure. Moreover, the electron diffraction pattern of this laser synthesized carbon form reasonably matches that of zinc blend diamond phase1030 and, accordingly, lead us to argue that the laser excitation synthesized a diamond-like phase. Figure 2c exhibits a High Resolution Image corresponding to a small region of the diffraction pattern area shown in the Fig. 2a. The whole image area (16 × 16 nm2) of the Fig. 2c presents planes with 0.205 nm distance (diamond characteristic plane distance) and an amorphous background, which is also noticed in Fig. 2a.


Synthesis of diamond-like phase from graphite by ultrafast laser driven dynamical compression.

Maia FC, Samad RE, Bettini J, Freitas RO, Vieira Junior ND, Souza-Neto NM - Sci Rep (2015)

High Resolution Electron Diffraction analysis of the diamond-like phase.SADs of the (a) laser created structures, and (b) its graphite precursor; (c) HREM micrograph of the laser created structure with the characteristic 0.205 nm d-spacing of the diamond phase evidenced by the zoom of a small area shown in the bottom inset; the upper inset shows the Fourier Transform of the whole image; (d) exhibits the corresponding electron diffraction peaks as a function of the inverse of the d-spacing for the polycrystalline graphite (PG, gray spectrum) and diamond-like phase (blue spectrum).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4493556&req=5

f2: High Resolution Electron Diffraction analysis of the diamond-like phase.SADs of the (a) laser created structures, and (b) its graphite precursor; (c) HREM micrograph of the laser created structure with the characteristic 0.205 nm d-spacing of the diamond phase evidenced by the zoom of a small area shown in the bottom inset; the upper inset shows the Fourier Transform of the whole image; (d) exhibits the corresponding electron diffraction peaks as a function of the inverse of the d-spacing for the polycrystalline graphite (PG, gray spectrum) and diamond-like phase (blue spectrum).
Mentions: The Raman spectrum of the laser-created structure transferred to a Cu grating (Fig. 1e) shows an expressively pronounced G-band at 1580 cm−1. While this band nearly dominates the spectrum, less intense vibrational resonances similar to the ones for the laser modified surface are also present. The dominance of the G-band closely resembles the Raman spectrum of HOPG26, therefore, indicating that the laser shockwaves induced reconstruction of the disordered arrangement of the pristine graphite into a more ordered graphitic phase. However, Selected Area of Diffraction (SAD) analysis of crystallites at multiple regions of this laser created structure (Fig. 1f) turned out being rather different from graphite, as can be noted in Fig. 2a (laser created particle) and 2b (polycrystalline graphite precursor). By assessing the related diffraction peaks plotted as a function of the inverse of the d-spacing (Fig. 2d), the laser induced changes are corroborated by the clear absence of the 0.338 nm interlayer distance – a signature of graphitic phase – in the created structure. Moreover, the electron diffraction pattern of this laser synthesized carbon form reasonably matches that of zinc blend diamond phase1030 and, accordingly, lead us to argue that the laser excitation synthesized a diamond-like phase. Figure 2c exhibits a High Resolution Image corresponding to a small region of the diffraction pattern area shown in the Fig. 2a. The whole image area (16 × 16 nm2) of the Fig. 2c presents planes with 0.205 nm distance (diamond characteristic plane distance) and an amorphous background, which is also noticed in Fig. 2a.

Bottom Line: Here, by exposing polycrystalline graphite to 25 fs laser pulses at 4 J/cm(2) fluence under standard air atmosphere, we demonstrated the synthesis of translucent micrometer-sized structures carrying diamond-like and onion-like carbon phases.Texturized domains of the diamond phase were also identified.Concerning different synthesized carbon forms, pulse superposition and singularities of the thermodynamical process, we pinpoint the synthesis mechanism by the laser-induced subsequent products energetically evolving to attain the diamond-like phase.

View Article: PubMed Central - PubMed

Affiliation: Laboratório Nacional de Luz Síncrotron (LNLS), Campinas, São Paulo 13083-970, Brazil.

ABSTRACT
Rapid variations of the environmental energy caused by ultrashort laser pulses have induced phase transitions in carbon allotropes, therefore bringing the promise of revealing new carbon phases. Here, by exposing polycrystalline graphite to 25 fs laser pulses at 4 J/cm(2) fluence under standard air atmosphere, we demonstrated the synthesis of translucent micrometer-sized structures carrying diamond-like and onion-like carbon phases. Texturized domains of the diamond phase were also identified. Concerning different synthesized carbon forms, pulse superposition and singularities of the thermodynamical process, we pinpoint the synthesis mechanism by the laser-induced subsequent products energetically evolving to attain the diamond-like phase.

No MeSH data available.


Related in: MedlinePlus