Effect of uniaxial stress on the Raman spectra of graphite fibers

Abstract

Measurements of the effect of uniaxial stress on the frequency of the k≊0 optical phonons in heat-treated benzene-derived graphite fibers have been performed using first-order Raman scattering. Application of uniaxial stress along the fiber axis is found to cause polarization-dependent splittings and shifts of the Raman peaks of the k≊0 doubly degenerate optical phonons. From these observed splittings and shifts, experimental values for the phenomenological coefficients which describe the changes in the elastic constant of these phonons with strain are determined. It is concluded that Raman spectroscopy can be used to characterize the local stress or strain conditions of graphite fibers nondestructively.