Defects in Crystals

Publisher Summary This chapter discusses the defects in crystals. Dislocations are an important class of defect in crystalline solids; therefore, an elementary understanding of crystallinity is required before dislocations can be introduced. Metals and many important classes of nonmetallic solids are crystalline, i.e. the constituent atoms are arranged in a pattern that repeats itself periodically in three dimensions. The actual arrangement of the atoms is described by the crystal structure. The crystal structures of most pure metals are simple, the three most common being the body-centered cubic, face-centered cubic, and close-packed hexagonal structures. The arrangement of atoms in a crystal can be described with respect to a three-dimensional net formed by three sets of straight, parallel lines. The lines divide space into equal sized parallelepipeds and the points at the intersection of the lines define a space lattice. Every point of a space lattice has identical surroundings.