Phase transformations in lead iodide polytypic crystals

Lead iodide polytypic crystals have been found to undergo phase transformation when annealed under vacuum (10 -4 torr) at temperatures ranging between 290 and 310 °C. Structural transformations involving several low identity period polytypes have been reported. The possible mechanism for phase transformation based on the nucleation, propagation and rearrangement of stacking faults has been suggested.