1. SOLID STATE

3. NaCl - STRUCTURE

4. TETRAHEDRAL VOIDS IN FCC

5. OCTRAEDRAL VOIDS IN FCC

6. UNIT CELL OF NaCl OR SPACE LATTICE OF CsCl
UNIT CELL & SPACE LATTICE
UNIT CELL OF NaCl OR SPACE LATTICE OF CsCl

7. NaCl - CCP PACKING

8. HORIZONTAL VIEW VERTICAL VIEW
NaCl - STRUCTURE
HORIZONTAL VIEW
VERTICAL VIEW

9. FRONT VIEW OF UNIT CELL OF NaCl 3 – D VIEW OF UNIT CELL OF NaCl

10. CsCl -STRUCTURE
chloride
CS+
cesium
Cl- _

11. 3 -D VEIW OF CsCl UNIT CELL

12. UNIT CELL AND SPACE LATTICE OF CsCl
Unit cell of CsCl
Space lattice of CsCl

13. CsCl - space lattice

14. IMPERFECTION IN SOLIDS
POINT DEFECTS
ELECTRONIC DEFECTS
IMPURITY
NON STOCHIOMETRIC
STOCHIOMETRIC
FRENKEL
SCHOTTKY
IONIC SOLIDS
COVALENT SOLIDS
METAL DEFICIENT
METAL EXCESS
EXTRA CATION
ANION VACANCY

15. IMPERFECTIONS IN SOLIDS
ANY DEPARTURE FROM PERFECTLY ORDERED ARRANGEMENT OF ATOMS IN CRYSTAL IS CALLED IMPERFECTION OR DEFECT. A+ B_ A+ B_ A+ B_ B_ A+ B_ A+ A+ B_ A+ B_ B_ A+ B_ A+
PERFECT CRYSTAL
IMPERFECT CRYSTAL X

16. TYPES OF POINT DEFECTS STOICHIOMETRIC NON-STOICHIOMETRIC
IMPURITY DEFECT

17. STOICHIOMETRIC DEFECTS
IF IMPERFECTIONS IN THE CRYSTAL ARE SUCH THAT THE RATIO BETWEEN THE CATIONS AND ANIONS REMAINS THE SAME AS REPRESENTED BY THE MOLECULAR FORMULA,THE DEFECTS ARE CALLED STOICHIOMETRIC DEFECTS.
SCHOTTKY DEFECTS
FRENKEL DEFECTS

18. SCHOTTKY DEFECT A+ B_ A+ B_ B_ A+ B_ A+ A+ B_ A+ B_ A+ B_ A+ B_

19. FRENKEL DEFECT A+ B_ A+ B_ B_ A+ B_ A+ A+ B_ A+ B_ A+ B_ A+ B_

20. DIFFERENCE BETWEEN SCHOTKKY & FRENKEL DEFECT
SCHOTTKY DEFECT
FRENKEL DEFECT
IT IS DUE TO EQUAL NUMBER OF CATIONS AND ANIONS MISSING FROM THE LATTICE SITE.
IT IS DUE TO MISSING OF IONS(CATIONS) FROM LATTTICE SITES AND THESE OCCUPY INTERSTITIAL SITES.
DECREASE IN DENSITY OF THE CRYSTAL.
NO EFFECT ON THE DENSITY OF THE CRYSTAL.
FOUND IN HIGHLY IONIC COMPOUNDS WITH HIGH CO-ORDINATION NUMBER AND HAVING CATIONS AND ANIONS OF SIMILAR SIZES.
e.g.-NaCl, KCl, CsCl
FOUND IN CRYSTALS WITH LOW COORDINATION NO. AND WHERE THE DIFFERENCE IN THE SIZE OF CATIONS AND ANIONS IS VERY LARGE.
e.g.-ZnS, AgCl, AgI .

21. NON-STICHIOMETRIC DEFECTS
IF AS A RESULT OF THE IMPERFECTIONS IN THE CRYSTAL THE RATIO OF THE CATIONS TO THE ANION BECOMES DIFFERENT FROM THAT INDICATED BY THE IDEAL CHEMICAL FORMULA,THE DEFECTS ARE CALLED NON-STOICIOMETRIC DEFECTS.
(A)METAL EXCESS
(B)METAL DEFICIENCY

22. METAL EXCESS BY ANION VACANCY A+ B_ A+ B_ B_ A+ B_ A+ A+ B_ A+ B_ A+
F-CENTRE A+ B_ A+ B_
A  A+ +
Na Na+ + e_ e_

23. METAL EXCESS A+ A+ B_ A+ B_ B_ A+ B_ A+ A+ B_ A+ B_
DUE TO EXTRA CATION IN THE INTERSTISTIAL SPACE A+ B_ A+ B_
METAL EXCESS MAY ALSO BE CAUSED BY AN EXTRA CATION OCCUPYING THE INTERSTITIAL SITE.THE ELECTRICAL ELECTRON PRESENT IN ANOTHER INTERSTITIAL SITE. B_ A+ B_ A+ A+ B_ A+ B_
ZnO  Zn++ + ½ O2 + 2e_ A+ B_ A+ B_ e_

24. METAL EXCESS BY ANION VACANCIES
BY PRESENCE OF EXTRA CATIONS IN THE INTERSTITIAL SITES
A NEGATIVE ION MAY BE MISSING FROM ITS LATTICE SITE,LEAVING A HOLE WHICH IS OCCUPUIED BY AN ELECTRON THEREBY MAINTAINING ELECTRICAL BALANCE.
METAL EXCESS MAY ALSO BE CAUSED BY AN EXTRA CATION OCCUPYING THE INTERSTITIAL SITE.THE ELECTRICAL NEUTRALITY IS MAITAINED BY AN ELECTRON PRESENT IN ANOTHER INTERSTITIAL SITE.

25. METAL DEFICIENCY A+ B_ A+ B_ B_ A+ B_ A+ A+ B_ A+ A++ B_ A+ B_ A+ B_
DUE TO CATION VACANCY A+ B_ A+ B_ B_ A+ B_ A+
CATION VACANCY A+ B_ A+
A++ B_
METAL ACQUIRING HIGHER CHARGE A+ B_ A+ B_

26. DEFECT IN FeS CRYSTAL Fe++ S_ _ Fe++ S_ _ S_ _ S_ _ Fe++ Fe++ Fe+++
DUE TO CATION VACANCY
Fe++
S_ _
Fe++
S_ _
S_ _
S_ _
Fe++
Fe++
Fe+++
CATION VACANCY
S_ _
Fe++
S_ _
Fe+++
Fe++
METAL ACQUIRING HIGHER CHARGE
S_ _
Fe++
S_ _
Fe++

27. METAL DEFICIENCY A+ B_ A+ B_ B_ A+ B_ A+ A+ B_ A+ A++ B_ A+ B_ A+ B_
DUE TO PRESENCE OF EXTRA ANION A+ B_ A+ B_ B_ A+ B_ A+
ANION OCCUPYIG INTERSTITIAL SITE A+ B_ A+
A++ B_
METAL ACQUIRING HIGHER CHARGE A+ B_ A+ B_ B_

28. IMPURITY DEFECTS (A) INTRODUCING IMPURITY DEFECT IN COVALENT SOLIDS
THESE DEFECTS ARISE WHEN FOREIGN ATOMS ARE PRESENT AT THE LATTICE SITE(IN PLACE OF HOST ATOMS) OR AT THE VACANT INTERSTITIAL SITES.
(A) INTRODUCING IMPURITY DEFECT IN COVALENT SOLIDS
(B) INTRODUCING IMPURITY DEFECT IN IONIC SOLIDS

29. IMPURITY DEFECT IN COVALENT SOLID
These defects arise when foreign atoms are present at the lattice site (in place of host atoms, forming substitutional solid solids) or at the vacant interstitial sites (forming interstitial solid solutions).
This is used in increasing the conductivity of semiconductors.

30. TYPES OF SOLIDS
SUBSTITUTIONAL SOLID
INTERSTITIAL SOLID

31. The Doping of Semiconductors
The addition of a small percentage of foreign atoms in the regular crystal lattice of silicon or germanium produces dramatic changes in their electrical properties, producing n-type and p-type semiconductors.
Pentavalent impurities
Impurity atomw with 5 valence electrons produce n-type semiconductors by contributing extra electrons.

32. N - TYPE SEMICONDUCTOR
The addition of pentavalent impurities such as antimony, arsenic or phosphorous contributes free electrons, greatly increasing the conductivity of the intrinsic semiconductor. Phosphorous may be added by diffusion of phosphine gas (PH3).

33. P TYPE SEMICONDUCTOR
The addition of trivalent impurities such as boron, aluminum or gallium to an intrinsic semiconductor creates deficiencies of valence electrons,called "holes". It is typical to use B2H6 diborane gas to diffuse boron into the silicon material.

34. IMPURITY DEFECT IN IONIC SOLID
These defect in ionic crystal arise due to the presence of some impurity ions at the lattice sites (in place of host ions) or at the vacant interstitial sites. If molten NaCl containing a little amount of SrCl2 is allowed to crystallise,some of the sites of Na+ ions are occupied by Sr++ ions
Sr++
Na+
Cl_
If NaCl is doped with mol % of SrCl2 , what is the concentration of cation vacancy ?
CATION VACANCY