Imperfercciones En Arreglos Atómicos (Ingles)

Imperfections in the Atomic and Ionic Arrangements:

*Point defects.

*Lineal defects.

*Superficial defects.

*Deslizamiento.

* Importance of defects.

Introduction:

In the history man has tried to find applications and materials that can be used. This has been studied for the conformation and structures of the materials. By that way we’ll try to show you more information about these crystalline defects on materials.

*POINT DEFECTS:

Point defects are localized disruptions in otherwise perfect atomic or ionic arrangements in a crystal structure. Even though we call them point defects, the disruption affects a region Involving several atoms or ions.

Types of defects:

*Vacancies.

*Frenkel defect.

*Shottky defect.

*Interstitial defects.

Vacancies:

A vacancy is produced when an atom or an ion is missing from its normal site in the crystal structure. When atoms or ions are missing, the overall randomness or entropy of the material increases, which increases the thermodynamic stability of a crystalline material.

All crystalline materials have vacancy defects.

Due to the large thermal energy near the melting temperature, there may be as many as one vacancy peer 1000 atoms.

May occur during solidification during the crystal growth.

Interstitial defects:

An interstitial defect is formed when an extra atom or ion is inserted into the crystal structure at a normally unoccupied position.

Interstitial atoms or ions, although much smaller than the atoms or ions located at the lattice point, are still larger than the interstitial sited that they occupy.

The introduction of interstitial atoms is one important way of increasing the strength of metallic materials. Unlike vacancies, once introduced, the number of interstitial atoms or ions in the structure remains nearly constant, even when the temperature is changed.

Substitutional defects:

Alloying elements can dissolve in the basic metal in two ways. They can replace host atoms in the lattice, which creates a Substitutional solid solution. The substitute or impurity atom is often larger than the atoms of the host material. This means there are strains imposed on the lattice.

A substitutional defect is introduced when one atom or ion is replaced by a different type of atom or ion. The substitutional atoms or ions occupy the normal lattice site. Substitutional atoms or ions may either be larger than the normal atoms or ions in the crystal structure, in which case the surrounding interatomic

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