Stoichiometric and non stoichiometric defects in the crystal lattice

In summary, stoichiometric defects refer to the presence of impurities or vacancies in a crystal lattice that do not disrupt the overall ratio of atoms in the compound, while non stoichiometric defects involve a change in the ratio of atoms in the compound. Stoichiometric defects can affect the properties of a crystal lattice, such as its electrical conductivity and mechanical strength, and can form through various factors such as deviations in the manufacturing process or exposure to high temperatures. While stoichiometric defects can sometimes be controlled or corrected, non stoichiometric defects are often difficult to control and can have a significant impact on the properties of the crystal lattice.
  • #1
venu_vikas
2
0
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 mineo:)
 
Chemistry news on Phys.org
  • #3


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
 

1. What is the difference between stoichiometric and non stoichiometric defects in the crystal lattice?

Stoichiometric defects refer to the presence of impurities or vacancies in a crystal lattice that do not disrupt the overall ratio of atoms in the compound. Non stoichiometric defects, on the other hand, involve a change in the ratio of atoms in the compound, leading to a deviation from its ideal chemical formula.

2. How do stoichiometric defects affect the properties of a crystal lattice?

Stoichiometric defects can have various effects on the properties of a crystal lattice, such as altering its electrical conductivity, mechanical strength, and optical properties. They can also lead to changes in the melting point and phase transitions of the compound.

3. What are some common examples of stoichiometric defects in crystal lattices?

Examples of stoichiometric defects include substitutional defects, where atoms of one type are replaced by atoms of another type in the lattice, and interstitial defects, where atoms occupy spaces between lattice points. Other examples include Frenkel and Schottky defects, which involve the movement of atoms within the lattice.

4. How do non stoichiometric defects form in a crystal lattice?

Non stoichiometric defects can form due to a variety of factors, such as deviations in the manufacturing process, exposure to high temperatures or radiation, or the presence of impurities in the compound. They can also arise from the intrinsic properties of the atoms in the lattice, such as their size and charge.

5. Can stoichiometric and non stoichiometric defects be controlled or corrected?

In some cases, stoichiometric defects can be controlled or corrected through careful manufacturing processes and the use of techniques like doping and annealing. However, non stoichiometric defects are often difficult to control and can have a significant impact on the properties of the crystal lattice.

Similar threads

  • Atomic and Condensed Matter
Replies
4
Views
2K
Replies
6
Views
2K
  • Chemistry
Replies
10
Views
2K
Replies
1
Views
612
Replies
8
Views
870
  • Advanced Physics Homework Help
Replies
3
Views
1K
Replies
1
Views
1K
  • Classical Physics
Replies
6
Views
2K
Replies
8
Views
763
Back
Top