Stoichiometric and non stoichiometric defects in the crystal lattice

[venu_vikas]

friends i studied abt the crystalline structures of compounds but i am just failing to understand the defects of the crystal lattice so i hope some one will help me in sorting out this problem of mine

 

[Gokul43201]

People have written entire books on defects in crystals. Do you have a specific question?

http://www.intute.ac.uk/sciences/cg...r=166&limit=0&submit.x=0&submit.y=0&submit=Go

 

[ravenprp]

Sure, I would be happy to help explain the concept of stoichiometric and non-stoichiometric defects in the crystal lattice.

First, let's define what a crystal lattice is. A crystal lattice is a regular, repeating arrangement of atoms or molecules in a solid. This arrangement is essential for the structure and properties of a crystal.

Now, let's talk about defects in the crystal lattice. Defects are irregularities or imperfections in the crystal lattice that can occur during the formation of a crystal. These defects can have a significant impact on the properties of the crystal.

Stoichiometric defects refer to defects that do not disrupt the overall ratio of atoms in the crystal. In other words, the number of atoms of each element in the crystal remains the same, but the arrangement is disrupted. There are three types of stoichiometric defects: vacancies, interstitials, and substitutional defects.

Vacancies occur when an atom is missing from its regular lattice site. This can happen due to the formation of an empty space or the movement of an atom from its original position. These vacancies can affect the density and mechanical properties of the crystal.

Interstitials occur when an atom occupies an interstitial site, which is a small space between regular lattice sites. This can happen when an atom of a different size or shape is incorporated into the crystal lattice, causing distortion.

Substitutional defects occur when an atom of a different element replaces an atom in the crystal lattice. This can happen if the two atoms have similar sizes and properties. Substitutional defects can significantly alter the properties of a crystal, such as its color or electrical conductivity.

On the other hand, non-stoichiometric defects refer to defects that disrupt the overall ratio of atoms in the crystal. This can happen due to the presence of extra atoms or the absence of some atoms in the crystal lattice. Non-stoichiometric defects can be of two types: excess defects and deficiency defects.

Excess defects occur when there are more atoms of a particular element in the crystal lattice than expected based on its chemical formula. This can happen due to the presence of impurities or the formation of extra vacancies.

Deficiency defects, on the other hand, occur when there are fewer atoms of a particular element in the crystal lattice than expected. This can happen if some atoms are missing from the crystal structure or if some atoms are present in different oxidation states.

In conclusion, stoichiometric and non-stoichiometric defects in