CRYSTAL DEFECT
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A perfect crystal refers to crystals with every atom of the same type in the correct position, does not exist. All crystals have some defects. Defects contribute to the mechanical properties of metals. In fact, “defect” is sort of a misnomer since these features are commonly intentionally used to manipulate the mechanical properties of a material. Adding alloying elements to a metal is one way of introducing a crystal defect. Nevertheless, the term “defect” will be used,crystalline defects are not always bad.
There are basic classes of crystal defects:
1)point defects:-It is due to lattice vacancies, self-interstitial atoms, substitution impurity atoms, and interstitial impurity atoms
2)linear defects:-IT forms due to dislocations.
3)planar defects :- Planar defects include grain boundaries, stacking faults and external surfaces.
Frenkel defect:-type of 'point defect' in a crystal structure where an atom or ion is displaced from its normal position to an interstitial one.
.
Schottky defect:-A Schottky defect
consists of a pair of anion and cation vacancies→ this maintains charge
neutrality.
