Micro-Raman study of diamondlike atomic-scale composite films modified by continuous wave laser annealing

Wan, Jian Wei; Pollak, Fred H.; Dorfman, Benjamin F.

doi:10.1063/1.364421

Cited by 11 publications

(13 citation statements)

References 14 publications

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“…Thermal expansion has the same effect on bond lengths (hence on n) as a tensile stress[472] 35. This equation neglects the statistical wavenumber dispersion in the reference and supposes wavenumbers are corrected for any instability of the Raman spectrometer.…”

mentioning

confidence: 99%

Raman Spectroscopy of nanomaterials: How spectra relate to disorder, particle size and mechanical properties

Gouadec

Colomban

2007

Progress in Crystal Growth and Characterization of Materials

928

724

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The purpose of this review is to provide non-specialists with a basic understanding of the information micro-Raman Spectroscopy (mRS) may yield when this characterization tool is applied to nanomaterials, a generic term for describing nano-sized crystals and bulk homogeneous materials with a structural disorder at the nanoscale e typically nanoceramics, nanocomposites, glassy materials and relaxor ferroelectrics. The selected materials include advanced and ancient ceramics, semiconductors and polymers developed in the form of dots, wires, films, fibres or composites for applications in the energy, electronic and aeronauticseaerospace industries. The text is divided into five sections:

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mentioning

confidence: 99%

Raman Spectroscopy of nanomaterials: How spectra relate to disorder, particle size and mechanical properties

Gouadec

Colomban

2007

Progress in Crystal Growth and Characterization of Materials

928

724

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“…Raman bands being a projection on the energy axis of the configurations distribution, crystallization of amorphous phases and subsequent grain-growth drastically reduce the bandwidths. Concerning carbon Raman spectra, resonance allows for sp 3 hybridization specific probing [25,27,67,68] . Comparison of sp 3 and sp 2 hybridization in fibers from different grades becomes possible.…”

Section: Raman Spectroscopy and Sic Fibers Micro/nano-structurementioning

confidence: 99%

Non-destructive mechanical characterization of SiC fibers by Raman spectroscopy

Gouadec

Colomban

2001

Journal of the European Ceramic Society

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The paper provides a comprehensive study on Raman spectroscopy versatility as a fast and non destructive tool for the prediction of the mechanical properties of SiC fibers derived from a polymeric precursor (NLM™, Hi™, Hi-S™, SA™ and Sylramic™ grades) or produced by CVD (SCS-6™ fiber), including in situ analysis in CMCs or MMCs. We show how the results of very simple spectra fitting are correlated with Young's modulus, tensile strength and microhardness. The reason why such a correlation exists, the common dependency of Raman signal and mechanical behavior to the micro/nanostructure of ceramics, is discussed. Keywords :SiC-fibers / Raman spectroscopy / Mechanical properties / Microstructure / Carbon ∂ Author to whom correspondence should be addressed Fax : 33 (0) 1 49 78 13 18 e-mail : colomban@glvt-cnrs.fr IntroductionThe reinforcement of ceramic materials by long ceramic fibers leads to low density and refractory materials, of high damage tolerance, that should be appropriate for metal alloys substitution in advanced engines (turbines) and waste treatment energy plants [1] . Ceramic fibers can also be incorporated directly in metal matrices to increase their high temperature mechanical properties [1] .SiC fibers, which are among the most stable fibers, have always been produced by the 3D reticulation of a polymeric precursor. This synthesis route leads to a high matter homogeneity and very smooth surfaces, the lack of defects explaining tensile strengths σ r as high as 3 GPa. SiC fibers have been widely studied, especially their aging [2][3][4][5][6][7] which evidenced that densification is linked to compositional changes (for instance the loss of some residual hydrogen [8] ). A peculiarity of ceramics issued from polymeric precursors is no impurities are concentrated at the grains boundaries. Abnormal grain growth is very common in the lack of such usual diffusion regulators [9] and the know-how of SiC fibers manufacturers consists in postponing the onset of SiC crystallization and grain growth, since a high correlation is anticipated with mechanical degradation. A close relationship has been evidenced, for instance, between the micro-hardness and short-range ordering in sol-gel prepared nanocrystalline oxides [10] and some authors have already pointed out fibers overall mechanical ability is governed by their microstructure [5,7,11] .The purpose of this paper is to try correlating, to the best extent possible, the tensile strength (σ r ), the Young's modulus (E) and the micro-hardness (μH) of different SiC fibers, either to Raman spectra or to "Raman Extensometry" S coefficient (measuring the straininduced shifts of Raman bands). Unlike most experimental methods intended to measure directly σ r and E, Raman analysis does not require extracting fibers from the matrix, either by mechanical grinding/crushing [12] or by chemical attack [13] . Only the most resistant fibers are extracted in the former case while fibers surface might be altered in the latter. Besides, it will always be difficult to extract...

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“…It is, therefore, of considerable interest to exam ine the influence of heat treatments on the electrical properties of silicon-carbon nanocomposite films. As shown by Wan et al [10], laser annealing leads to changes in Raman spectra of silicon-carbon nano composite films, which indicate that the hybridization of electron orbitals for some of the carbon atoms changes from sp 3 (characteristic of diamond) to sp 2 (characteristic of graphite). From this finding, they inferred that laser radiation led to graphitization of the films (the formation of graphite nanocrystals).…”

Section: Resultsmentioning

confidence: 82%

Effect of nanocrystalline phase on the electrical conductivity of amorphous tantalum-containing silicon-carbon films

et al. 2014

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We have studied the effect of metal concentration on the electrical conductivity of tantalum con taining silicon-carbon nanocomposite films. The results demonstrate that carrier transport in the films fol lows different mechanisms at low and high metal concentrations. When the concentration of the conducting nanocrystalline tantalum carbide phase is under 28 at %, conduction is due to hopping. Conducting phase concentrations from 28 to 34 at % correspond to a percolation threshold. At higher tantalum carbide concen trations, conduction is through the tantalum carbide nanocrystals. The effect of heat treatments on the elec trical conductivity of the material is analyzed.

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Micro-Raman study of diamondlike atomic-scale composite films modified by continuous wave laser annealing

Cited by 11 publications

References 14 publications

Raman Spectroscopy of nanomaterials: How spectra relate to disorder, particle size and mechanical properties

Raman Spectroscopy of nanomaterials: How spectra relate to disorder, particle size and mechanical properties

Non-destructive mechanical characterization of SiC fibers by Raman spectroscopy

Effect of nanocrystalline phase on the electrical conductivity of amorphous tantalum-containing silicon-carbon films

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