Final answer:
Voids, gaps, and cracks are defects in crystalline solids that can form during crystallization or from external stressors. These can include vacancies, substitution impurities, interstitial atoms, and can be intentionally created through doping.
Step-by-step explanation:
Defects such as voids, gaps, and cracks are typically found in crystalline solids and can be formed during the solidification process or due to external factors after the formation of the crystal. Types of defects include vacancies, where atoms or ions are missing from their designated positions; interstitial atoms, where atoms or ions occupy spaces between the regular atomic positions; and substitution impurities, where foreign atoms replace the original atoms in the crystal lattice structure. Additionally, intentional impurities, known as doping, are added to change the properties of the crystal, such as altering electrical properties in semiconductor manufacturing.
Point defects, like Frenkel and Schottky defects, occur due to the misplacement of ions and vacancies in ionic crystals, while line defects affect the mechanical properties of solids. Plane defects occur along a two-dimensional surface and can greatly influence properties such as catalytic activity in materials used as catalysts due to their increased surface area.