1. APPLIED
PHYSICS

2. Text Books
Book 1: Applied Physics by Dr. M.
Chandra sekhar & Dr. Appala naidu,
V.G.S. Book links
Book 2 Introduction to Solid State Physics
by C. Kittel, Wiley Eastern Ltd.
Book 3Nanotechnology by Mark Ratner
and Daniel Ratner, Pearson Education
2

3. Suggested / Reference Books
Book 1 Material science and Engineering
by V Raghavan PHI publishers
Book 2 Material Science by M Arumugam,
Anuradha agencies
Book 3Solid state physics by Ashcroft,
Mermin, Thomson learning
Book 4Solid state physics by Gupta &
Kumar,K.Nath & Co.
3

4. Book 5: Applied Physics by
P.K.Palaniswamy,Scitech
Publications(India)Pvt.Ltd.
Book 6: Material Science by MS Vijaya & G
Rangarajan, Tata Mc Graw Hill
Book 7: Applied Physics by K. Vijay Kumar &
T.Srikanth, S. Chand & Company Ltd.
Book 8: Nano materials by A.K. Bandyopadhyay,
New Age International Publishers
4

5. UNIT-1
Bonding in solids
Crystal structures
X-ray diffractions
5

6. APPLIED PHYSICS
CODE : 07A1BS05
I B.TECH
CSE, IT, ECE & EEE
UNIT-1: CHAPTER1
NO. OF SLIDES :31
6

7. UNIT INDEX
UNIT-I
S.No. Module Lecture PPT Slide
No. No.
1 Introduction L1 8
2 Types of bonding L2 9-29
3. Estimation of L3 30
cohesive energy.
4. Made lung constant. L4 31
7

8. Lecture-1
Introduction
Introduction: Generally matter consists in three
states i.e., depending on their internal structure.
Normally the states are solid state, liquid state,
and gaseous state. In solids stated as the closer
collection of atoms result in bulk materials called
solids. Solids are usually strong and exhibit
elastic character. Solids can be broadly classified
as either crystalline or Non-crystalline. The
arrangement of atoms in a solids is determined
by the character, strength and directionality of the
binding forces. The bonds are made of attractive
and repulsive forces.
8

9. Lecture-2
Types of Bonding
An atom consists of positively charged nucleus
surrounded by negatively charged electron cloud. When
two atoms are brought closer there will be both attractive
and repulsive forces acting upon. The value of the energy
need to move an atom completely away from its
equilibrium position is a measure of “Bonding Energy “
between them.
This energy varies depending on the type of bonding.
The bonds are made up of attractive and repulsive
forces. Different charge distributions in the atoms give
rise to different types of bonding.
9

10. Bonds generally classified into five
classes.
1. Ionic bonding
2. Covalent bonding
3. Metallic bonding
4. Hydrogen bonding
5. Vander walls bonding.
10

11. Ionic Bonding: An ionic bonding is
the attractive force existing between
a positive ion and a negative ion
when they are brought into close
proximity. These ions are formed
when the atoms of different elements
involved lose or gain electrons in
order to stabilize their outer shell
electron configurations.
11

12. Properties of ionic solids:
1.Ionic solids are crystalline in nature.
2.They are hard and brittle.
3.They have high melting and boiling
points.
4.Since all the electrons are tightly
bound with the ions, ionic solids are
good insulators of electricity.
12

13. 5.They are soluble in polar solvents and
insoluble in Non-polar solvents.
6.In an ionic crystal, a cation is surrounded
by as many anions as possible and vice-
versa.
Examples of ionic solids:
NaCl, KCl, KBr, MgO, MgCl2,KOH, and
Al2O3 are few examples of ionic solids. 13

14. Covalent Bonding:
The arrangement
of electrons in an
outer shell is
achieved by a
process of
valence electron
sharing rather
than electron
transfer.
14

15. Properties of Covalent solids:
1.Covalent bonds are directional. Change in the
direction of the bond results in the formation of
different substance.
2.Since different covalent solids have very much
different bond strengths, they exhibit varying
physical properties. For example, the diamond is
the hardest substance with very high melting
point. It is a very good insulator of electricity.
3.Covalent solids are hard and brittle. They posses
crystalline structure.
15

16. 4.When compared with ionic solids, these solids
have relatively low melting and boiling
points.
5.Pure covalent solids are good insulators of
electricity at low temperatures.
6.When covalent crystals are doped with certain
impurities, they becomes semi-conductors.
Examples of Covalent solids:S,I, Ge, Si,
diamond and graphite.
16

17. 17

18. Metallic Bonding: The valence electrons
from all the atoms belonging to the
crystal are free to move throughout the
crystal. The crystal may be considered as
an array of positive metal ions embedded
in a “cloud” or “sea” of free electrons.
This type of bonding is called metallic
bonding.
18

19. Properties of Metallic solids:
1.Metallic bonds hold the atoms
together in metals.
2.Metallic bonds are relatively weak.
3.Metallic solids are malleable and
ductile.
4.Metallic bond is non directional.
19

20. 5.They have high number of
free electrons.
6.They possess high electrical
and thermal conductivity.
7.Metals are opaque to light.
Examples of metallic solids:
Sodium, Copper, Gold, Silver,
Aluminum.
20

21. Hydrogen Bonding:
Covalently bonded atoms often produce an
electric dipole configuration with hydrogen
atom as the positive end of the dipole if
bonds arise as a result of electrostatic
attraction between atoms, it is known as
hydrogen bonding.
21

22. Properties of Hydrogen solids:
1.The hydrogen bonds are directional.
2.The bonding is relatively strong as compared
to other dipole-dipole interactions.
3.Hydrogen bonded solids have low melting
points.
4.Since no valence electrons are available in
such solids they are good insulators of
electricity.
5.They are soluble in both polar and nonpolar
solvents.
22

23. 6.They are transparent to light.
7.Since elements of low atomic numbers form
such solids, they have low densities.
8.When water is in the form of ice, hydrogen
bond results in lower density; but when it
melts, it becomes more closely packed liquid
and hence its density increases.
Example of hydrogen bonded solids: Water
molecule in the form of ice, ammonia
molecules.
23

24. Van der Waals(Molecular) Bonding:
Weak and temporary (fluctuating) dipole
bonds between hydrogen are known as
van der Waals bonding and they are
nondirectoinal. (OR)
Secondary bonding arising from the
fluctuating dipole nature of an atom with
all occupied electron shell filled is called
van der waals bonding.
24

25. Properties of Van der waals bonding:
1.Van der waals bonds are nondirectional.
2.Van der waals bonding is weaker than the
hydrogen bonding.
3.Van der waals bonded solids have low melting
point.
4.Since no valence electrons are available, such
solids are good insulators of electricity.
25

26. 5.They are soluble in both polar and
non polar liquids.
6.They are usually transparent to
light.
Examples of Van der Waals
bonded solids: Solid neon, Solid
argon.
26

27. 1. The mechanical, thermal,
electrical and other properties of
materials are related to chemical
bonding and structure.
2. The atoms/molecules in solids
are very strongly held together
by interatomic/ intermolecular
forces called bonding in solids.
27

28. 3. The force that holds atoms together is
called bonding force. Under the bonded
condition the potential energy is
minimum.
4.The amount of energy required to separate
the atoms completely from the structure is
called cohesive energy. This energy is also
called energy of dissociation.
28

29. Primary Bondings have bond
energies in the range of 0.1-
10eV/bond. Ionic, Covalent and
metallic bondings are the examples.
Secondary Bondings have energies
in the range of 0.001-0.5eV/bond.
Hydrogen bonding and van der waals
bonding are the examples.
29

30. Lecture-3
Cohesive energy of NaCl molecule:
30

31. Lecture-4
The Madelung constant is a
function of crystal structure
and can be calculated from
the geometrical arrangement
of ions in the crystal.
31

32. UNIT INDEX
UNIT-I
S.No. Module Lecture PPT Slide
No. No.
1 Introduction-space L5 3-10
lattice –unit cell
6 Lattice parameters. L6 11-27
bravais lattices
7 Structure and packing L7 28-30
fractions.
8. Miller indices. L8-9 31-33
32

33. Lecture-5
INTRODUCTION
Matter is classified into three kinds, they are
solids, liquids and gases. In solids, all the atoms
or molecules are arranged in a fixed manner.
Solids have definite shape and size, where as in
liquid and gasses atoms or molecules are not
fixed and cannot form any shape and size.
On basis of arrangement of atoms or molecules,
solids are classified into two categories, they are
crystalline solids and amorphous solids.
33

34. CRYSTALLINE SOLIDS AMORPHOUS SOLIDS
1. In crystalline solids, the 1. In amorphous solids, the
atoms or molecules are atoms or molecules are
arranged in a regular and arranged in an irregular
orderly manner in 3-D manner, otherwise there
pattern, called lattice. is no lattice structure.
2. These solids passed 2. These solids do not
internal spatial symmetry posses any internal
of atomic or molecular spatial symmetry.
orientation.
3. If a crystal breaks, the 3. If an amorphous solid
broken pieces also have breaks, the broken pieces
regular shape. are irregular in shape.
Eg: M.C : Au, Ag,Al, Eg : Glass, Plastic, Rubber.
N.M.C: Si, Nacl, Dia.
34

35. LATTICE POINTS :
Lattice points denote the position of atoms or
molecules in the crystals.
SPACE LATTICE :
The angular arrangement of the space positions of
the atoms or molecules in a crystals is called space
lattice or lattice array.
35

36. 2D-SPACE LATTICE :
It is defined as an infinite array of points in 2-
D space in which every point has the same
environment w.r.t. all other points.
The dots represent the lattice points in which
atoms can be accommodated. Taking O as an
arbitrary origin in XY – plane constructed.
b
The two translations vectors ā and ē are taken
OP b
along X-axis and Y-axis respectively. The
resultant vector T can be represented as
T=n1ā +n2 Where n1, n2 are arbitrary integers.
36

37. 3D- Space Lattice
It is defined as an infinite array of points in
3D-Space in which every point has the same
environment w.r.t. all other points.
In this case the resultant vector can be
b
expressed as T=n1ā +n2 +n3 . Where n1, n2, n3
c
b, c
are arbitrary integers and, ā, & are
translational vector along X,Y,Z-axis
respectively
37

38. BASIS :
 Certain atoms or molecules are attached
to each lattice point in the crystal structure.
These atoms or molecules attached to any
lattice point form the basis of a crystal
lattice. Hence, crystal structure = Lattice
+ Basis.
 In order to convert the geometrical array
of points molecules are located on the
lattice points.
38

39. The repeating unit assembly – atom,
molecule, ion or radical – that is located at
each lattice point is called the BASIS.
The basis is an assembly of atoms
identical in composition, arrangement and
orientation. Thus, Again we say that the
crystal structure is formed by logical
relation
Space lattice + Basis = CRYSTAL
STRUCTURE.
39

40. Unit Cell :
Unit cell of a crystal is the smallest volume of a
crystalline solid or geometric figure from which
the entire crystal is built up by translational
repetition in three dimensions.
Since the unit cell which reflects the structure of
the crystal structure of the crystal lattice has all
the structural properties of the given crystal
lattice, it is enough to study the shape and
properties of the unit cell to get the idea about
the whole crystal
40

41. Lecture-6
LATTICE PARAMETERS OF AN UNIT CELL
The lines drawn parallel to the lines of
intersection of any three faces of the unit cell
which do not lie in the same plane are called
crystallographic axes.
An arbitrary arrangement of
crystallographic axes marked X,Y,&Z. The
angles between the three crystallographic
axes are known as interfacial angles or
interaxial angles.
41

42. The angle between the axes Y and Z = α
The angle between the axes Z and X = β
The angle between the axes X and Y = γ
 The intercepts a,b&c define the dimensions of
an unit cell and are known as its primitive or
characteristic intercepts on the axes. The three
quantities a,b&c are also called the fundamental
translational vectors.
42

43. BRAVAIS LATTICES
A 3dimensional lattice is generated by
repeated translation of three non-coplanar
vectors a,b &c.
There are only 14 distinguishable ways of
arranging points in 3d space.
These 14 space lattices are known as
Bravais lattices.
43

44. SIMPLE CUBIC
44

45. BODY CENTRED CUBIC
45

46. FACE CENTRED CUBIC
46

47. TETRAGONAL
47

48. BODY CENTRED TETRAGONAL
48

49. ORTHORHOMBIC
49

50. BODY CENTRED
ORTHORHOMBIC
50

51. BASE CENTRED
ORTHORHOMBIC
51

52. FACE CEN TRED
ORTHORHOMBIC
52

53. MONOCLINIC
53

54. BASE CENTRED MONOCLINIC
54

55. TRICLINIC
55

56. RHOMBOHEDRAL
56

57. HEXAGONAL
57

58. Lecture-7
Atomic packing factor is the ratio of
volume occupied by the atoms in an unit
cell to the total volume of the unit cell. It
is also called packing fraction.
The arrangement of atoms in different
layers and the way of stacking of
different layers result in different crystal
manner.
58

59. Metallic crystals have closest packing in
two forms (i) hexagonal close packed and
(ii) face- centred cubic with packing
factor 74%.
The packing factor of simple cubic
structure is 52%.
The packing factor of body centred cubic
structure is 68%.
59

60. Lecture-8
MILLER INDICES
In a crystal orientation of planes or faces can
be described interms of their intercepts on the
three crystallographic axes.
 Miller suggested a method of indicating the
orientation of a plane by reducing the
reciprocal of the intercepts into smallest whole
numbers.
o These indices are called Miller indeces
generally represented by (h k l).
60

61. All equally spaced parallel planes have the
same miller indices.
. If a normal is drawn to a plane (h k l), the
direction of the normal is
[h k l].
Separation between adjacent lattice planes in a
cubic crystal is given by d= u/ ---h 2+k2+l2.
where a is the lattice constant and (h k l) are
the Miller indices.
61

62. Important features in miller
indices Lecture-9
1. When a plane is parallel to any axis, the intercept of
the plane on that axis is infinity. Hence its Miller
index for that axis is zero.
2. When the intercept of a plane on any axis is
negative a bar is put on the corresponding Miller
index.
3. All equally spaced parallel planes have the same
index number (h k l).
62

63. 4. If a plane passes thought origin, it is defined
in terms of a parallel plane having non-zero
intercept.
5. If a normal is drawn to plane (h k l), the
direction of the normal is (h k l).
63

64. UNIT INDEX
UNIT-I
S.No. Module Lecture PPT Slide
No. No.
9 Braggs law. L10 3-9
10 Laue method L11 10-15
11. powder method. L12 16-20
64

65. Lecture-10
X-Ray Powder Diffraction
65

66. Lecture-10
66

67. Lecture-10
X-Ray Powder Diffraction (XRPD) is
one of the most powerful techniques
for analyzing the crystalline nature of
solids. XRPD capabilities include
micro-diffractometry, flat plate or
capillary sample configuration,
spinning and rocking methods,
variable temperature and humidity
conditions, and a unique sample
conveyor system to overcome sample
inhomogeneity effects.
67

68. Lecture-10
XRPD is perhaps the most widely used X-ray
diffraction technique for characterizing materials.
As the name suggests, the sample is usually in a
powdery form, consisting of fine grains of single
crystalline material to be studied. The technique
provides information that cannot be obtained any
other way. The information obtained includes
types and nature of crystalline phases present,
structural make-up of phases, degree of
crystallinity, amount of amorphous content,
microstrain & size and preferred orientation of
crystallites. The technique is also used for
studying particles in liquid suspensions or
polycrystalline solids (bulk or thin film materials).
68

69. Lecture-10
The term 'powder' means that the crystalline
domains are randomly oriented in the sample.
Therefore, when the 2-D diffraction pattern is
recorded, it shows concentric rings of scattering
peaks corresponding to the various d spacings
in the crystal lattice. The positions and the
intensities of the peaks are used for identifying
the underlying structure (or phase) of the
material. This phase identification is important
because the material properties are highly
dependent on structure (think, for example, of
graphite and diamond).
69

70. Lecture-10
Powder diffraction data can be collected
using either transmission or reflection
geometry, as shown below. If the particles
in the powder sample are randomly
oriented, both methods will yield the same
results.
70

71. Lecture-10
Single crystal diffraction L
e
 Laue’s method - λ variable, θ fixed. c
t
 Rotating crystal method - λ fixed, θ variable
u
r
to some extent. e
-
1
0
 Why not single crystal methods?
• It may be difficult to obtain a single
crystal.
• The usual form of a material may be
polycrystalline.
• Problems with twinning or phase
transitions complicate structural
assignments. 71

72. Lecture-11
Powder diffraction
In this method the crystal is reduced to a
fine powder and is placed in a beam of
monochromatic X-rays. Each particle is a
tiny crystal or an assemblage of smaller
crystals randomly oriented with respect to
the the incident beam.
Powder methods - λ fixed, θ variable.
72

73. Lecture-11
The diagram shows only two scattering planes, but
implicit here is the presence of many parallel, identical
planes, each of which is separated from its adjacent
neighbor by a spacing d.
Constructive interference occurs when (A+B)/λ = n,
coinciding with Bragg’s law, nλ= 2dsin θ. The integer n
refers to the order of diffraction. For n = 1, (A+B) = λ and
73

74. Lecture-11
• Angles are used to calculate the interplanar
atomic spacings (d-spacings). Because every
crystalline material will give a characteristic
diffraction pattern and can act as a unique
‘fingerprint’, the position (d) and intensity (I)
information are used to identify the type of
material by comparing them with patterns for over
80,000 data entries in the International Powder
Diffraction File (PDF) database, complied by the
Joint Committee for Powder Diffraction Standards
(JCPDS). By this method, identification of any
crystalline compounds can be made even in
complex samples.
74

75. Lecture-11
The position (d) of the diffracted peaks also provides
information about how the atoms are arranged within the
crystalline compound (unit cell size or lattice parameter).
The intensity information is used to assess the type and
nature of atoms. Determination of lattice parameter helps
understand extent of solid solution (complete or partial
substitution of one element for another, as in some
alloys) in a sample.
The ‘d’ and ‘I’ from a phase can also be used to
quantitatively estimate the amount of that phase in a
multi-component mixture.
The width of the diffracted peaks is used to determine
crystallite size and micro-strain in the sample.
75

76. Lecture-
If the sample consists of tens of randomly 11
oriented single crystals, the diffracted beams
are seen to lie on the surface of several cones .
76

77. Instrument geometries Lecture-11
There are several ways of collecting XRPD patterns:
Camera methods: Guinier, Debye-Scherrer, Gandolfi,
77

78. The Debye – Scherrer powder camera Lecture-1
A photographic film is placed around the inner circumference of the
camera body. The incident beam enters through a pinhole and almost the
whole diffraction pattern is recorded simultaneously. At the point of
entrance the angle is 180° and at the exit the angle is 0°.
78

79. L Lecture-12
 e
Pinhole source
c
 Film located on camera
t
body u
r
 Rod shaped sample e
 Sample rotates to give
-
better “randomness”1
0
 Almost complete
angular range covered
79

80. View of an instrument Lecture-12
80

81. Lecture-10
Lecture-10
81

82. X-Ray Powder Diffraction Instruments
Lecture-12
82