What is the Difference Between Stoichiometric and Nonstoichiometric Defects?

The main difference between stoichiometric and nonstoichiometric defects lies in their effect on the stoichiometry of a compound:

• Stoichiometric defects do not disturb the stoichiometry of a compound, meaning they do not change the ratio between cations and anions present in the crystal structure. There are several types of stoichiometric defects, such as interstitial defects, Schottky defects, and Frenkel defects. These defects are also known as intrinsic or thermodynamic defects.
• Nonstoichiometric defects disturb the stoichiometry of a compound, changing the ratio between cations and anions in the crystal structure. These defects can result in the formation of lattice imperfections due to deviations from stoichiometric composition. There are two main types of nonstoichiometric defects: metal excess defects and metal deficiency defects.

In summary, stoichiometric defects maintain the balance between cations and anions in a compound, while nonstoichiometric defects disrupt this balance.

Comparative Table: Stoichiometric vs Nonstoichiometric Defects

Here is a table comparing stoichiometric and nonstoichiometric defects:

Stoichiometric defects are those that do not change the ratio between cations and anions present in the compound, while nonstoichiometric defects disturb this ratio.