Question

Give two differences between Schottky and Frenkel defects in ionic solids.

Answer 1

Hint: Schottky defect and Frenkel defect are related to the lattice arrangement in the solid state. In this arrangement cations and anions are missing from the lattice. These defects differ due to some reasons like size of atoms, overall mass of the lattice, and density of the solid etc.

Complete step by step answer:
Now, we will compare both the defects simultaneously.
We know these defects are found in the lattice arrangement of ionic solids.
First, Schottky defect occurs in the crystals where the size difference of cation and anion is small, although in the Frenkel defect size of anion is large as compared to that of the cation.
Second, in the former one, both cation and anion leave the lattice, whereas in the latter one smaller ion (cation) leaves the lattice site.
Third, we can say that in the Schottky defect due to vacancy formation, density of crystal decreases, and in the Frenkel defect density of solid remains same.
Fourth, let us know the examples, Schottky defect can be found in NaCl, KCl, KBr, and many more, whereas Frenkel defect can be seen in ZnS, AgCl, and many other solids.

Note: Don’t get confused between both the defects. Both defects differ in many perspectives. In the Frenkel defect the density of solid remains the same as no atom leaves the site because when cation leaves the lattice site, it occupies the interstitial site.