where n is the number of corners, r i the radius of the i th corner curvature, and r max the radius of the maximum inscribed circle (Fig. ). It is clear on the graph of the Figure that most of the particles display a soft edge morphology [0.6-0.95], with a median roundness factor of 0.73 (Fig. ) compared to a cube geometry (0.53). Taken altogether, the morphology of the crystals are more of a 'potato-like' shape rather than a single crystal with sharp facets. Only a small number of particles (less than 15%) display surfaces with significant flatness than can be attributed to aligned crystallographic planes, i.e. with roundness between 0.5 and 0.6. More research is required to understand the relationship between crystal quality and particle shape, which is readily accessible from electron microscopy.