The document provides an overview of X-ray diffraction and its applications, including an explanation of Bragg's law, which describes the conditions for constructive interference of X-rays by crystal lattice planes. It details various X-ray diffraction techniques such as Laue photographic method, Bragg’s x-ray spectrometer method, rotating crystal method, and powder crystal method, highlighting their procedures and uses. Additionally, it enumerates the applications of X-ray powder diffraction in identifying unknown crystalline materials, determining structural properties, and assessing the purity and characteristics of samples.

1. Presented by:
Pratik Siddhapura
M.Pharm 1st Year
Sem- 1

2. CONTENT
 X- ray diffraction
 Bragg’s law
 Different X-ray diffraction techniques
1. Laue photographic method
2. Bragg’s X-ray spectrometer method
3. Rotating crystal technique
4. X-ray powder technique
 Type of crystal
 Application of x-ray diffraction

3.  X-ray crystallography works based on X-ray
diffraction principle: It means that scattering of x-ray
by crystal.
X-ray diffraction is based on constructive
interference of monochromatic X rays and crystalline
sample.
X- ray diffraction

4. BRAGG’S LAW
• Diffraction occurs only when Bragg’s Law is satisfied.
• Bragg law identifies the angles of the incident radiation relative to the
lattice planes for which diffraction peaks occurs.
• Bragg derived the condition for constructive interference of the X-rays
scattered from a set of parallel lattice planes.
• When the X-rays strike a layer of a crystal, some of them will be reflected.
These two x-ray beams travel slightly different distances.
• Connecting the two beams with perpendicular lines shows the
difference between the top and the bottom beams.
• For a crystalline solid, the waves are scattered from lattice planes
separated by the inter planar distance d.
• When the scattered waves interfere constructively, they remain in phase
since the difference between the path lengths of the two waves is equal to
an integer multiple of the wavelength.
• The path difference between two waves undergoing interference is given
by 2dsinθ, where θ is the scattering angle.

5. crystal

6. ACCORDING TO THE 2Θ DEVIATION, THE PHASE SHIFT
CAUSES CONSTRUCTIVE (LEFT FIGURE) OR DESTRUCTIVE
(RIGHT FIGURE) INTERFERENCES.

7. THE LENGTH AB IS THE SAME AS BC SO THE TOTAL DISTANCE
TRAVELED BY THE BOTTOM WAVE IS EXPRESSED BY:
AB= D SINΘ
BC = D SINΘ
AB+ BC= 2D SINΘ
NΛ = 2D SINΘ
CONSTRUCTIVE INTERFERENCE OF THE RADIATION FROM SUCCESSIVE
PLANES OCCURS WHEN THE PATH DIFFERENCE IS AN INTEGRAL
NUMBER OF WAVE LENGTHS. THIS IS THE BRAGG LAW.

8. 1.Laue photographic method
Transmission method
 In this method the crystal is held
stationary in a beam of x-rays ,
after passing through the crystal
is diffracted and is recorded on a
Photographic plate. Laue pattern
can be used to orient crystals for
solid State experiments.

9. 1.Laue photographic method
Back reflection method
 The film is placed between the x-
ray source and the crystal. The
beams which are diffracted in
backward direction are recorded.

10. 2.BRAGG X-RAY SPECTROMETER
METHOD

11. Construction:-
• Bragg's Spectrometer consists of a collimator containing two slits S1 and
S2 made up of lead, through which X-ray is passed.
• A turn table is situated in-front of the collimator on which crystal is
placed.
• Ionization chamber collects the reflected X-ray
Procedure:-
• A fine beam of a monochromatic X-ray is made to fall on the crystal.
• The crystal reflects the X-rays which are collected by the ionization
chamber.
• Turn table is rotated till a sharp increase in the intensity is detected.
• The sudden increase in intensity suggests that Bragg's Law is satisfied at
the given angle θ.
• Then the inter-planar spacing can be determined by using Bragg's Law
nλ = 2d.sinθ

12. 3. ROTATING CRYSTAL
METHOD
The X- rays are generated in the X-ray tube and then the beam is
made by monochromator.
The beam is allowed to pass through collimating system which
permits a parallel
X-rays.
 Then the X –ray beam is made to fall on crystal which is
mounted on a rotating shaft.
 When x-ray strike on crystal plane, it will produce a spot on
photographic film.

14. X – RAY DIFFRACTION PATTERN

15. 4. POWDER CRYSTAL METHOD
• When an X-ray is shined on a crystal, it diffracts in
a pattern characteristic of the structure. In powder
X-ray diffraction, the diffraction pattern is obtained
from a powder of the material.
• Powder diffraction is often easier and more
convenient than single crystal diffraction since it
does not require individual crystals be made.
Powder X-ray diffraction (XRD) also obtains a
diffraction pattern for the bulk material of a
crystalline solid, rather than of a single crystal.

16. Powder crystal method

17. TYPE OF CRYSTAL

25. Application
• X-ray powder diffraction is most widely used for the
identification of unknown crystalline materials (e.g.
minerals, inorganic compounds).
• characterization of crystalline materials
• identification of fine-grained minerals such as clays and
mixed layer clays that are difficult to determine optically
• determination of unit cell dimensions

26. • To identify crystalline phases and orientation
To determine structural properties:
• To measure thickness of thin films and multi-layers
• To determine atomic arrangement
• measurement of sample purity

27. • Particle size determination
• Determination of Cis - Trans isomerism
• It is used to assess the weathering and degradation of
natural and synthetic , minerals.
• Tooth enamel and dentine have been examined by
xrd.