Optical and interferometric studies on the cleavages of synthetic diamonds and their etch patterns

Abstract

Synthetic diamonds manufactured by the General Electric Company, U.S.A., have been cleaved and optical and interferometric studies made on the cleavage faces. These are compared with similar studies made on cleavages of natural diamonds. The technique developed for cleaving small synthetic diamonds is described. The cleavage faces have been etched in potassium nitrate at 600° C. The etch patterns produced consist only of isolated pits having rectilinear sides and sharp corners. They are of various sizes. The usual stratigraphical etch pattern and large number of crowded tiny pits observed on natural diamond cleavages are missing on the cleavages of our synthetic diamonds. The absence may be attributed to the controlled conditions of growth and infrequency of impurity atoms. It is conjectured that the different sizes of the pits may be due to local precipitation of large numbers of impurities and not because of local variation in rates of etching. Matched cleavage faces have been etched and some correspondence in localization and sizes of the pits is established in the etch pattern. Etched cleavage faces have been examined interferometrically and it is shown that the pits produced are very shallow and that the attack starts only at surface defects and there is no surface dissolution in general. The cleavage faces have also been etched in KC1O3. It is conjectured that our synthetic diamond is more resistant to etch than natural diamond.