1. Pleae answer these questions briefly and correctly.
1) for a ternary system, three component are present; tempeature is also a variable. What is the
max number if phases that may be present for a ternary system, assuming pressure is held
constant?
2) Describe the Frenkel and Schottky defects formed in AgBr, respectively.
3) If electroneutrality is to be preserved, what point defects are possible in NaCl when a Ca^2+
substitues for Na^+ ions. How many of these defects exist for every Ca^2+ ion?
Solution
AND
2) Describe the Frenkel and Schottky defects formed in AgBr, respectively.
When the both the cations and anions are absent from the crystal lattice it is called Schottky
defect. This defect is shown when the anions and cations have comparable size. The Frenkel
defect is shown by ionic molecules when their is a large difference in the size of anions and
cations. The smaller anions are very much mobile and they occupy interstitial site. AgBr has
cations and anions with comparable size and hence it shows Schottky defect but the Ag+ ion is
very much mobile and it easily occupies interstitial place getting dislocated from its original
place, that's why the ionic crystal AgBr shows both Schottky and Frenkel defects.