Undoped ZnO crystals grown from the melt are known to form lightly colored and nearly transparent nanorods of hexagonal shape due to a higher growth rate along the c-axis 30 . Crystals of ZnO doped in low (1-2 %) concentrations grow without a preferential growth orientation and with a relatively uniform size distribution often with deformed hexagonal facets and colors ranging from yellow-orange for the samples doped with Sb to black for the As-doped samples (Fig. ). As concentration of a dopant increases, samples demonstrate a tendency to form a blend of rod-like crystals very similar to undoped ZnO (but of a much smaller size) and colored deformed aggregates of crystals attributing to doped ZnO (Fig 1b). Addition of an impurity expectedly impedes crystal growth and leads to formation of smaller crystals.