Point Defects on Crystal Lattice

An ideal crystal is one in which every atom is of the same type and occupies its correct position in the crystal lattice. However, in reality, such perfect structures rarely exist, as most crystals contain defects. These crystal defects can be categorized into three main classes: point defects, linear defects, and planar defects. Point defects occur at specific points in the lattice where atoms are missing or irregularly placed. Common types of point defects include lattice vacancies, self-interstitial atoms, substitution impurity atoms, and interstitial impurity atoms. Linear defects involve groups of atoms that are out of alignment or in irregular positions within the lattice. Linear defects are also known as dislocations. Planar defects are discontinuities that occur between different regions of the crystal. Types of planar defects include grain boundaries, stacking faults, and external surfaces.