Crack nucleation in mgo single crystals

Three main types of crack formation in plastically deformed MgO crystals have been observed. They are all due to internal stresses of macroscopic character resulting from the difficulty of mutual penetration of perpendicular dislocation bands and the consequent geometrical incompatibilities of plastic deformation. The accompanying internal stresses are strongly reduced by plastic deformation, mainly in the form of kinking; however, they often give rise to crack formation.