Examine the given defective crystal:
Answer the following questions:
(i) What type of stoichiometric defect is shown by the crystal?
(ii) How is the density of the crystal affected by this defect?
(iii) What type of ionic substances shows such defect?
(i) Schottky defect is shown by the mentioned crystal, as an equal number of cations and anions are missing in the crystal lattice.
(ii) This defect leads to decrease in density, as an equal number of the cations and anions are missing from the crystal lattice. A number of such defects in ionic solids are quite significant. For example, in NaCl, there are approximately 106 Schottky pairs per cm3 at room temperature.
(iii) This kind of defect is shown by that ionic substance in which the cations and anions are of almost similar sizes.
Examples: NaCl, KCl and CsCl.