the simplest of the point defects is a vacancy or vacant lattice site ,one normally occupied from which atom is missing is called vacancy
a self-interstitial is an atom from a crystal that is crowded into an interstitial site , a small void space that under ordinary circumstances is not occupied.
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Vacancy defects are missing atoms within a crystal lattice, while self-interstitial defects are extra atoms that occupy interstitial spaces within the lattice. Vacancies result in a decrease in density, while self-interstitials increase density. Both types of defects can affect the material's mechanical and electrical properties.
Impurities can be incorporated into a crystal structure through a process called doping, where foreign atoms are intentionally added during crystal growth. These impurities can occupy lattice sites, forming substitutional defects, or they can be present in between lattice sites, creating interstitial defects. Doping can alter the electronic and optical properties of the material, making it useful for various applications.
The radius ratio for AgBr is intermediate. Thus it shows both frenkel and schottky defects. The major defect in AgBr is the Frenkel defect. It has a rocksalt structure i.e. CCP lattice of of Br with atoms of Ag occupying all octahedral holes.Ag moves from octahedral to tetrahedral sites causing only cations to precipitate. Schottky defect arise due to missing of ions from their lacttice point and frenkel arise when the mmissing ions occupy interstitial sites. in AgBr, ag+ ion is small in size and when removed from lacttice point they can occupy interstitial site and therefore show both frenkel and schottky defect. SCHOTTKY Defect in AgBr is exhibited due to precipitation of both Cations and Anions.
Ionic defects are structural imperfections in a crystal lattice that result from the presence of missing or extra ions in the lattice. These defects can affect the material's properties, such as electrical conductivity or optical behavior, by influencing the movement of ions within the lattice. Examples of ionic defects include vacancies, interstitial ions, and substitutional impurities.
AgBr can exhibit both Frenkel and Schottky defects due to the relative size difference between the cation (Ag+) and anion (Br-) in the crystal lattice. The smaller Ag+ cation can easily migrate to a vacant cation site through a Frenkel defect, while the creation of cation and anion vacancies simultaneously forming a Schottky defect is also feasible due to the ionic nature of the compound.
In welding, "melt through" occurs when excessive heat causes the base metal to be penetrated, resulting in a hole. "Burn through" happens when the heat is so intense that the molten metal actually burns away portions of the base metal, leading to thinning or complete loss of material. Both defects can weaken the weld joint and compromise its integrity.