Question

Frenkel and Schottky defects are
A) Nucleus defects
B) Non-crystal defects
C) Crystal defects
D) None of these

Answer 1

Hint: Frankel and Schottky are a type of defects. The various defects arise due to the missing of cation and anion from the crystals which causes vacant sites. These are found in solid crystal compounds or lattices.

Complete Step by Step Answer:
When a cation or anion leaves its site and occupies the interstitial position of a crystal lattice then the defect arises is called Frankel defect.

The major characteristics of the Frankel defect are:
- In this defect there is a very large difference in size between cation and anion.
- In this defect either cation or anion leave the solid crystal.
- Atoms or the ions do not move out of the crystal permanently in this defect.
- Here generally one vacancy is formed.
- The density of the solid remains the same.

In Schottky defect the equal number of anions and cations are removed from the crystal lattice to produce vacancy in the crystal which in turns causes defect in the crystal.

In this defect at first one cation is removed from the crystal solid. Now to maintain the neutrality of the crystal lattice an anion is also removed from the crystal lattice.

The major characteristic of Schottky defect are:
- In this defect there is a very small difference in size between cation and anion.
- In this defect both the Cation and anion leave the solid crystal.
- Atoms or the ions move out of the crystal permanently in this defect.
- Here generally two vacancies are formed, one for cation and another one is for the anion.
- The density of the solid decreases.
Thus the correct option is C.

Note: Due to these defects the properties of the crystals changed. Due to frankel and Schottky defects the crystal shows various colours in the visible range. This defect decreases the conductivity of the crystals.