Effect of tin-doping on polytypism of melt-grown crystals of cadmium iodide

The effect of doping of metallic tin in cadmium iodide crystals has been systematically studied. The method of zone melting has been employed both for purification and for the growth of single crystals of cadmium iodide. The doping has been carried out by zone levelling technique. The as-grown crystals have been characterized by X-ray diffraction and physical methods. All the crystals have been found to consist of the most common polytype 4H. Unlike the case of pure undoped crystals of cadmium iodide grown from melt, all the X-ray photographs showed the presence of arcing. None of the photographs showed the presence of streaking. Besides, the doped crystal were found to be harder than the crystals of undoped cadmium iodide. Unlike the undoped crystals, cleavage in the doped crystals was found to be difficult and highly localized. The results have been discussed.