Plastic deformation of crystalline materials is
caused by nucleation and multiplication of dislocations under an external force
(A and B). It has been generally believed that brittle inorganic semiconducting
materials have difficulty in formation of dislocations because of their strong
chemical bonds. However, researchers found that a great number of dislocations
are generated and multiplied in ZnS crystals during deformation in darkness
(C), resulting in the extraordinary plasticity that researchers observed. Image courtesy of Atsutomo Nakamura.