Study of elementary steps on the (0Â 0Â 1), (1Â 0Â 0) and (0Â 1Â 0) cleavage faces of potassium bichromate single crystals

The elementary cleavage steps on the (0 0 1), (1 0 0) and (0 1 0) faces of potassium bichromate crystals are analysed by calculations of the step energy. The steps of minimum energy determined theoretically are confronted with those observed on the cleavage planes. It was found that: (1) the occurrence of cleavage steps oriented along low-index directions on the cleavage faces of KBC crystals corresponds to steps of low energy, (2) the structure of crystals has an pronounced influence on the morphology of cleavage faces regarding their perfection, (3) the relative perfection of different cleavage faces can be explained in terms of χ coefficient defined as the ratio of the surface energy of the (h k l) plane to the minimum step energy on this plane and (4) the lower the value of the coefficient χ, the better is the cleavage perfection of the face.