Can you obtain a crystal free of line defects? Solution Dislocations are linear defects around which some of the atoms of the crystal lattice are misaligned.There are two basic types of dislocations, the edge dislocation and the screw dislocation. \"Mixed\" dislocations, having both aspects are also very common. It is the dislocations and their ability to readily move (and interact) under the influence of various stresses induced by externally applied oads that lead to the characteristic property called malleability of common metallic materials. So defects linear are helpful for certain properties.