All Physics Faculty Presentations

Title

Structural Evolution of Annealed Graphitic Amorphous Carbon

Document Type

Conference Paper

Journal/Book Title/Conference

Bulletin of the American Physical Society

Volume

40

Publication Date

1995

Abstract

We have used Raman scattering to investigate the effects of annealing on graphitic amorphous carbon (g-C). g-C is an amorphous phase of carbon primarily composed of sp^2 -planar-bonded carbon and no long-range order. g-C samples were annealed in 100^\circ C steps up to 1050^\circ C . Using 2.54 eV and 2.71 eV laser excitations, the Raman spectra show a clear progression from an amorphous phase to a nanocrystalline phase as the g-C is annealed to higher temperatures. The 1580 cm^-1 band emerges from the broad g-C spectrum and narrows, indicating ordering as the material slowly evolves toward graphite, but remains substantially broader than the 1581 cm^-1 E_2g^2 phonon of bulk graphite. Simultaneously, the 1350 cm^-1 (zone-edge) mode appears as structural order is gradually established. The Raman spectra were found to have a dependence on the excitation used: 2.41 eV excitation enhanced the 1350 cm^-1 band as compared to 1.92 , 2.54 , and 2.71 eV light. There is precedence for this type of enhancement in both graphite-like and diamond-like disordered materials, and the origin of this effect in our samples will be discussed.

Comments

Bull. Am. Phys. Soc. 40(3), 538 (1995). APS Meeting, San Jose, CA