Question

What is the effect of the presence of schottky defects on the density of a crystal ?

Answer 1

Hint: A schottky defect basically consists of an unoccupied anion and cation sites in a stoichiometric ratio. .they The crystal creates a vacancy or what we call as the gap at their original sites and this results in the decrease in the overall density of the crystal or we can say as they reduce the total number of ions that is why there is a decrease in total density of the crystal.

Complete step by step answer:
A schottky defect basically consists of an unoccupied anion and cation sites in a stoichiometric ratio.
When we talk about a simple crystal lattice it consists of a single anion vacancy and a single cation vacancy .When we talk about the general formula it is basically $A_xB_Y$ where “X” are the vacancies of A and Y are the vacancies of B . thus, we can say that the overall stoichiometry and the charge neutrality are conserved .when we talk conceptually then we can say that schottky defect is generated when a vacancy is created by the unit cell .this type of defect is basically observed when there is very small size difference between the cation and the anion which further together constitute the material or the substance.
Now we will further discuss in detail how that schottky defect affects the density of the crystal.
In everyday language we can say that the schottky defect is a defect which is equal in number of the oppositely charged particles which are what we called as anions and cations .they the crystal creating a vacancy or what we call as the gap at their original sites and this results in the decrease in the overall density of the crystal or we can say as they reduce the total number of ions that is why there is a decrease in total density of the crystal.
For making it understand more easily we can summarise the entire process in the following steps:
Firstly we can say that the movement of ions takes place due to which a space or a vacancy is created.
Secondly, then in order to maintain the electrical neutrality or to make the solid overall neutral these vacancies are basically created .
The vacancies are then free to move about their own entities as the vacancy defect is created so this will lead to decrease in the density of the crystal .

Note: We should keep in mind the stoichiometry of the schottky defect which says that the $A_xB_Y$ where “X” are the vacancies of A and Y are the vacancies of B. Thus, we can say that the overall stoichiometry and the charge neutrality are conserved. Also as vacancy is created so for sure it will decrease the overall density of the solid or the crystal lattice.