Name: Radius Ratio and Coordination Number
Uploaded: 2019-07-19
Duration: 3 min 49 s
Description: The radius ratio plays a very important role in the determination of a structure in an ionic crystal. Watch the video to know more about the radius ratio of...

Question

State the difference between Schottky and Frenkel defects? Which of these two changes the density of the solid and why?

Accepted Answer

Schottky defect Frenkel defect

1. It arises when equal number of cations and anions are missing from their normal lattice sites. 1. It arises when ions(generally cations) leave their lattice sites and occupy interstitial sites between the lattice points.

2. It is common in highly ionic compounds with high coordination number and having cations and anions of almost equal size. 2. It is common in those ionic compounds which possess low coordination number and anions are much larger than the cations.

3. It decreases the density of the crystal. 3. It does not affect the density of the crystal.

4. It has no effect on the dielectric constant by the crystal. 4. It increases the dielectric constant of the crystal because similar charges come closer in this defect.

Schottky defects occur in crystals that have a small difference in cationic and anionic sizes whereas Frenkel defects occur in those with a large difference in size. The atoms do not leave the crystal in the Frenkel defect whereas, in the Schottky defect, there is a reduction in the number of atoms. The density of the crystal is affected by the Schottky defect and not by the Frenkel defect.

State the difference between Schottky and Frenkel defects? Which of these two changes the density of the solid and why?

Important Questions on States of Matter: Solid State

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