Question

Scotty defect is observed in____________.

• A. $NaCl$
• B. $KCl$
• C. $CsCl$
• D. $BaC{l}_2$

Answer 1

Answer: (A), (B), (C)

The correct options are
A $KCl$
B $NaCl$
C $CsCl$

Schottky defect is the defect which is produced when one cation and anion are missing from their respective positions leaving behind a pair of holes. The crystal as a whole remains neutral because the number of missing positive ions (cations) and negative ions (anions) is the same.
For Schottky defect, co-ordination numbers of the ions should be high., Examples of ionic solids showing this defect are NaCl, CsCl, KCI, KBr etc.
Consequences of Schottky defect are as follows:
1. Density of the crystal decreases.
2. The crystal begins to conduct electricity to small extent by ionic mechanism.
3. The presence of too many voids lowers lattice energy or the stability of the crystal.