Moreover, impurities may slow down normally accelerated growth along the c-axis causing crystals to have a shape with no preferential direction. A visible change of shape and color combined with no Sb-associated peaks on XRD patterns implies successful incorporation of the dopant in ZnO structure. Sometimes the resulting samples might represent a blend of orange spherical and dark rod-like particles (Fig. ), which indicates a non-uniform distribution of the dopant. This effect usually holds for higher concentrations of Sb (2-5%).