Experimental evidence for the existence of the four possible structures of diamond

Abstract

Experimental evidence has been obtained for the existence of the four possible structures of diamond from X-ray and spectroscopic studies. The co-existence of the two variants of the tetrahedral structure in one and the same specimen and the heterogeneity arising therefrom have been confirmed from the observed increased intensities of X-ray reflections in such diamonds. Using the oscillating crystal method and a diamond in which the two structures of the octahedral type co-exist in adjacent layers of the crystal, it is observed that the Bragg reflections exhibit a waviness such as should be observed if there be a difference in the crystal spacings of the alternate layers. The observed difference in crystal spacings thus deduced is of the order of 5 parts in 10,000. The Raman line corresponding to the fundamental lattice vibration shows a definite width in the case of the octahedral type of diamond which agrees at least in the order of magnitude, with the expected difference in the vibration frequencies of the two octahedral structures.