Phase transformations studies on a disordered structure of lead iodide

Phase transformation studies on disordered crystals of lead iodide grown by the “gel” technique have been performed. It has been shown that the degree of disorder is reduced as a result of annealing, and that an ordered structure may appear. In some cases the disorder is completely eliminated and only the ordered structure is the product of transformation. The results have been explained in terms of the annihilation of randomly distributed stacking faults and the nucleation of new ordered stacking faults, or the migration of extended defects to a more stable configuration. Electron microscope evidence is presented in support of the above explanation.