What is grain boundary defects?
A grain boundary is the interface between two grains, or crystallites, in a polycrystalline material. Grain boundaries are 2D defects in the crystal structure, and tend to decrease the electrical and thermal conductivity of the material.
What is a point defect and a line defect?
Point imperfections (Zero dimensional defects) 2. Line imperfections (one dimensional defects) 3. Plane or surface imperfections (Two dimensional defects)
What is the difference between stoichiometric and nonstoichiometric defects?
Stoichiometric defects do not disturb the stoichiometry of a compound whereas non-stoichiometric defects are defects in crystal structures that disturb the stoichiometry of the compounds. Types of non-stoichiometric defects are metal excess defects, metal deficiency defects etc.
What are metal deficient defects How are these caused?
-Metal deficiency defect arises due to a vacant lattice site caused by missing cation. Thus one of the nearest metal ions will acquire an extra positive charge to prevent or maintain the electrical neutrality of the crystalline compound.
What is the metal deficiency defect?
In metal deficiency defect, a cation is missing from its lattice site. To maintain electrical neutrality, one of the nearest metal ions acquires an extra positive charge. This type of defect occurs in compounds where the metal can exhibit variable valency. e.g., Transition metal compounds.
What is the effect of Frenkel defect?
A Frenkel defect is a type of point defect in crystalline solids named after its discoverer Yakov Frenkel. The defect forms when an atom or smaller ion (usually cation) leaves its place in the lattice, creating a vacancy, and becomes an interstitial by lodging in a nearby location.
What is the effect of density in Schottky defect?
The presence of Schottky defect lowers the density of the crystal. It does not affect the density of the crystal. It is generally shown by ionic solids hav- ing high co-ordination number and cations and anions of similar sizes, for example, NaCl, CsCl.
Can the number and type of defects be varied and controlled?
The number and type of defects can be varied and controlled (e.g., T controls vacancy conc.) Defects affect material properties (e.g., grain boundaries control crystal slip).