This document discusses different types of crystal defects including point defects like vacancies and interstitials, and line and plane defects. It describes specific point defects in detail such as vacancy defects, self-interstitial defects, Schottky defects, and Frenkel defects. The key differences between Schottky and Frenkel defects are outlined. Impurity defects caused by foreign atoms substituting into the crystal lattice or occupying interstitial sites are also summarized. Finally, non-stoichiometric defects resulting from a metal deficiency or excess are mentioned.

1. XII- CHEMISTRY

2. Disorders or irregularities in the arrangement of
constituent particles of a solid crystal are called defects
or imperfections.
Crystal Defect

3. Point Defects
Line Defects
Plain Defects

4. Stoichiometric
Defect
Vacancy Defect
Self interstitial Defect
SchottkyDefect
Frenkel Defect
Impurity Defect
SubstitutionalImpurity
Defect
Interstitial Impurity
Defect
Nonstoichiometric
Defect
Metal deficiency
Defect
Metal excess Defect

5. The ratio of number of atoms or number of cations and
anions of compounds remains the same as represented by its
chemical formula
i) Vacancy Defect :

6. ii) Self interstitial Defect in elemental solid :
Density increases
Extra particle occupies an empty space in crystal lattice

7.  A particle gets shifted from its original lattice point and occupies an
interstitial space in crystal.
 Density doesn’t change.
ii) Self interstitial Defect in elemental solid :

8. iii) Schottky Defect :

9. iv) Frenkel Defect :

10. Difference between Schottky and frenkel defect
Schottky defect frenkel defect
Occurs in those ionic crystals where
difference in size between cation and anion
is small.
Occurs in those ionic crystals where size of
anion is quite large as compared to that of
the cation.
Ions have high coordination number Ions have low coordination number
Both cation and anion leave the solid
crystal.
Only the smaller ion (cation) leaves its
original lattice site; whereas, the anion
remains in original lattice sites.
Two atoms reduce from the crystal for
each hence schottky defect reduces density
of the solid.
The number of atoms present in the crystal
before and after defect remains same,
hence density of the solid remains same
e.g. NaCl, KCl, AgBr e.g. ZnS, AgCl

11.  Foreign atoms are present in the crystal lattice.
i) Substitutional Impurity Defect
Solid solutions of metals Vacancy thruogh aliovalent impurity

12. ii) Interstitial Impurity Defect

13. The ratio of number of atoms or number of cations and anions of
compounds become different from that indicated by its chemical
formula
i) Metal deficiency Defect

15. ii) Metal excess Defect
Defect due to extra positive charge occupying interstitial position

16. Defect due to anion vaccancies
F - Center

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