What is defects in crystals?

Defects in crystals refer to imperfections in the orderly arrangement of atoms within a crystalline structure. These defects can take various forms, including point defects (such as vacancies and interstitials), line defects (like dislocations), and surface defects (such as grain boundaries). They significantly influence the material's physical properties, including strength, electrical conductivity, and optical characteristics, ultimately affecting its performance in various applications. Understanding and controlling these defects is crucial in materials science and engineering.