Phonon Spectrum of Graphite

Young, James A.; Koppel, J.U.

doi:10.1063/1.1695699

Cited by 106 publications

(35 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…For these lattice directions also the Debye-Waller factors have been determined and from them the mean-square vibration amplitudes of the atoms and the effective Debye temperatures have been calculated. Graphit kristallisiert in einem nach ihm benannten hexagonalen Gitter (Bernal, 1924;Wyckoff, 1963) (Yoshimori & Kitano, 1956;Young & Koppel, 1965) berechnet werden. Die hierzunotwendige umfangreiche Maschinenrechnung ist bisher noch nicht durchgeffihrt worden.…”

Section: Bestimmung Der )[Nderung Der Gitterkonstanten Mad Des Anisotunclassified

“…Die hierzunotwendige umfangreiche Maschinenrechnung ist bisher noch nicht durchgeffihrt worden. Auf Rechenanlagen wurde ffir Graphit nur das Frequenzspektrum ermittelt (Yoshimori & Kitano, 1956;Young & Koppel, 1965). Dieses ist zerlegt in ein Spektrum g ~ (co) mit dem Polarisationsvektor e ~ parallel zur c-Achse und in ein Spektrum g±(og) mite 2 senkrecht zur c-Achse (Fig.…”

Section: Bestimmung Der )[Nderung Der Gitterkonstanten Mad Des Anisotunclassified

“…Gitters (A(u~)) im Bereich yon 300-2150°K etwa 4 mal so gross wie senkrecht zu c (A(uZ,) Aus den Frequenzspektren von Young & Koppel (1965) kiSnnen ffir den Temperaturbereich yon 300-1150 °K mittlere Debye-Temperaturen yon 625 °K f/Jr e ~ parallel c und yon 1460°K f/Jr e ~ senkrecht c berechnet werden. Diese Werte sind in guter fJbereinstimmung mit dem Experiment (vergl.…”

Section: A(uz)=[(u2(t))-(u2(300))] Parallel Zur C-achse Desunclassified

See 2 more Smart Citations

Bestimmung der Ånderung der Gitterkonstanten und des anisotropen Debye–Waller-Faktors von Graphit mittels Neutronenbeugung im Temperaturbereich von 25 bis 1850°C

Ludsteck¹

1972

Acta Cryst Sect A

View full text Add to dashboard Cite

With a double-axis spectrometer the neutron-scattering cross section da/dI2 of polycrystalline graphite has been measured as a function of temperature. The elastic coherent scattering yielded the variations of the lattice constants for the directions parallel and perpendicular to the c axis of the hexagonal graphite lattice. For these lattice directions also the Debye-Waller factors have been determined and from them the mean-square vibration amplitudes of the atoms and the effective Debye temperatures have been calculated. Einleitung und theoretische Grundlagen

show abstract

Section: Bestimmung Der )[Nderung Der Gitterkonstanten Mad Des Anisotunclassified

Section: A(uz)=[(u2(t))-(u2(300))] Parallel Zur C-achse Desunclassified

See 1 more Smart Citation

Bestimmung der Ånderung der Gitterkonstanten und des anisotropen Debye–Waller-Faktors von Graphit mittels Neutronenbeugung im Temperaturbereich von 25 bis 1850°C

Ludsteck¹

1972

Acta Cryst Sect A

View full text Add to dashboard Cite

show abstract

“…A band was observed at 1332 cm −1 [73], with a better understanding of the first and second orders reported in 1970 [74]. The phonon spectrum of graphite was modelled and obtained for the first time in 1965 [75,76]. Only two modes are Raman active according to the point group symmetry analysis.…”

Section: Historical Aspectsmentioning

confidence: 99%

A Guide to and Review of the Use of Multiwavelength Raman Spectroscopy for Characterizing Defective Aromatic Carbon Solids: from Graphene to Amorphous Carbons

2017

View full text Add to dashboard Cite

sp 2 hybridized carbons constitute a broad class of solid phases composed primarily of elemental carbon and can be either synthetic or naturally occurring. Some examples are graphite, chars, soot, graphene, carbon nanotubes, pyrolytic carbon, and diamond-like carbon. They vary from highly ordered to completely disordered solids and detailed knowledge of their internal structure and composition is of utmost importance for the scientific and engineering communities working with these materials. Multiwavelength Raman spectroscopy has proven to be a very powerful and non-destructive tool for the characterization of carbons containing both aromatic domains and defects and has been widely used since the 1980s. Depending on the material studied, some specific spectroscopic parameters (e.g., band position, full width at half maximum, relative intensity ratio between two bands) are used to characterize defects. This paper is addressed first to (but not limited to) the newcomer in the field, who needs to be guided due to the vast literature on the subject, in order to understand the physics at play when dealing with Raman spectroscopy of graphene-based solids. We also give historical aspects on the development of the Raman spectroscopy technique and on its application to sp 2 hybridized carbons, which are generally not presented in the literature. We review the way Raman spectroscopy is used for sp 2 based carbon samples containing defects. As graphene is the building block for all these materials, we try to bridge these two worlds by also reviewing the use of Raman spectroscopy in the characterization of graphene and nanographenes (e.g., nanotubes, nanoribbons, nanocones, bombarded graphene). Counterintuitively, because of the Dirac cones in the electronic structure of graphene, Raman spectra are driven by electronic properties: Phonons and electrons being coupled by the double resonance mechanism. This justifies the use of multiwavelength Raman spectroscopy to better characterize these materials. We conclude with the possible influence of both phonon confinement and curvature of aromatic planes on the shape of Raman spectra, and discuss samples to be studied in the future with some complementary technique (e.g., high resolution transmission electron microscopy) in order to disentangle the influence of structure and defects.

show abstract

“…As it can be seen, the agreement is remarkable and clearly illustrates the power and utility of the ab initio approach. The figure also shows the ab initio phonon frequency distribution for graphite compared to the one used in the current (ENDF/B-VII) compilations of thermal neutron scattering cross sections [22]. The agreement is reasonable, however, in the low energy region that is of interest in thermal neutron scattering calculations, the ab intio model shows higher frequency values.…”

Section: Graphitementioning

confidence: 77%

Development and Validation of Temperature Dependent Thermal Neutron Scattering Laws for Applications and Safety Implications in Generation IV Reactor Designs

Hawari¹

2008

View full text Add to dashboard Cite

Project Objective: The overall objectives of this project are to critically review the currently used thermal neutron scattering laws for various moderators as a function of temperature, select a well documented and representative set of experimental data sensitive to the neutron spectra to generate a data base of benchmarks, update models and models parameters by introducing new developments in thermalization theory and condensed matter physics into various computational approaches in establishing the scattering laws, benchmark the results against the experimental set. In the case of graphite, a validation experiment is performed by observing neutron slowing down as a function of temperatures equal to or greater than room temperature. In addition, an analysis is performed to understand the implications of the obtained results on the ability to accurately determine the operating and safety characteristics (e.g., the moderator temperature coefficient of reactivity, buildup and depletion of transuranium elements) of given reactor designs, which include Generation IV nuclear power systems, advanced research reactors and power reactors for space applications.Final Project ReportJune 20, 2008 DE-FG07-02SF22514 Background:This project performs a thorough evaluation and update of the thermal neutron scattering kernels for several materials that are of interest in the nuclear technology field. This includes materials of primary interest to modern reactor concepts such as graphite, zirconium hydride, beryllium, beryllium oxide, light water and polyethylene, which are well known neutron moderators/reflectors. The work includes updating the computational models that are used in current thermal neutron calculations, and introducing modern Ab-Initio methods for computing the fundamental vibrational data that are needed to generate the scattering kernel for crystalline materials. A neutron slowing-down-time experiment will be conducted to benchmark the temperature dependent scattering kernel in graphite. Finally, an assessment will be made of the potential implications of the results on the operating characteristics of reactors. Summary:The project resulted in a general refinement of the treatment of thermal neutron scattering for the studied materials. For materials that are considered to be strong coherent scatterers of neutrons (e.g., graphite and beryllium), a more complete theoretical approach was developed and implemented for calculating inelastic thermal neutron scattering cross sections. In addition, a general ab initio approach for obtaining the basic information needed for thermal scattering calculations (e.g., the phonon frequency distributions) was developed. Furthermore, experimental measurements were performed to benchmark thermal neutron interactions in graphite. A transmission measurement was performed at the National Institute of Standards and Technology using 1 meV neutrons. This measurement produced total cross section values (below the Bragg Cut-off) for samples of pyrolitic and reactor grade graphite. A s...

show abstract

Phonon Spectrum of Graphite

Cited by 106 publications

References 6 publications

Bestimmung der Ånderung der Gitterkonstanten und des anisotropen Debye–Waller-Faktors von Graphit mittels Neutronenbeugung im Temperaturbereich von 25 bis 1850°C

Bestimmung der Ånderung der Gitterkonstanten und des anisotropen Debye–Waller-Faktors von Graphit mittels Neutronenbeugung im Temperaturbereich von 25 bis 1850°C

A Guide to and Review of the Use of Multiwavelength Raman Spectroscopy for Characterizing Defective Aromatic Carbon Solids: from Graphene to Amorphous Carbons

Development and Validation of Temperature Dependent Thermal Neutron Scattering Laws for Applications and Safety Implications in Generation IV Reactor Designs

Contact Info

Product

Resources

About