Question

Schottky defect generally appears in:
(A) NaCl
(B) KCl
(C) CsCl
(D) All of these

Answer 1

Hint :Let us first get some idea about the ionic compound. Ions of opposite charge are neatly packed to form crystalline solids. When metals react with non-metals, ionic compounds are formed. Metals lose electrons to complete their octet in a reaction between metals and nonmetals, whereas non-metals gain electrons to complete their octet. Ionic compounds are formed when metals and non-metals react.

Complete Step By Step Answer:
Let us know about the Schottky defect. The Schottky defect (small shot effect) is named after Walter H. Schottky, a well-known German physicist who was awarded the Royal Society's Hughes medal in 1936 for discovering it. In his model, he describes that in ionic crystals, defects form when oppositely charged ions exit their lattice sites, resulting in vacancies. These vacancies are also produced to keep the crystal's charge neutral. The model goes on to say that the underlying atoms shift to fill these voids as well. The defect is often referred to as a lattice vacancy defect when it occurs in non-ionic crystals. Schottky defect, on the other hand, differs from frenkel defect in that atoms in schottky defect permanently exit the crystal, while atoms in frenkel defect normally remain inside the solid crystal.
Schottky defects are most common in highly ionic compounds with similar-sized anion and cation. Schottky defects are found in strongly ionic compounds with a high number of coordination bonds. Eg. NaCl,KCl,CsCl, KBr, AgBr.
So, Option(D) is correct.

Note :
The size difference between cation and anion is very small in this defect. Both the cation and the anion leave the solid crystal. In this atoms leave the crystal permanently as well. Atoms are also permanently expelled from the crystal.