The effect of uniaxial stress along [001] and [111] on the zone-center optical phonon of diamond has been studied, and the corresponding deformation potentials determined. The results are interpreted in terms of a valence-field-force model. A fit to the theory of our experimental results and the measured variation of the elastic constants under hydrostatic stress, a total of six data with three adjustable parameters, allows all the third-order elastic constants to be determined.

• Received 24 March 1978

DOI:https://doi.org/10.1103/PhysRevB.18.901