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1. X- RAY
DIFFRACTION
PRINCIPAL, INSTRUMENTATION AND
APPLICATIONS
SUBMITTED BY : MR. PRATHAMESH .H. GHODAKE
( M.SC STUDENT OF ANALYTICAL CHEMISTRY)
VIVEKANANDA COLLEGE KOLHAPUR
(AN EMPOWERED AUTONOMOUS INSTITUTE)

2. X- RAY DIFFRACTION
1. Introduction to X-Ray Diffraction
2. History & Discovery
3. Concept of Crystallography
4. Principal and Instrumentation of XRD
5. Bragg’s Law for XRD
6. Types of X-Ray Diffraction Techniques
7. Applications of XRD
8. Advantages and Limitations XRD

3. INTRODUCTION TO X-RAY DIFFRACTION
This is the versatile and non-destructive analytical technique used to analyse
physical properties of any crystal by using X – rays.
XRD is based on the constructive interference of monochromatic X-rays and a
crystalline sample. The diffracted X-rays are used to determine crystal structure,
interplanar spacing, and phase identification

4. HISTORY AND DISCOVERY OF XRD
X-rays were discovered 1895 by
“Wilhelm Conrad Röntgen”, a German
physicist, while he was experimenting
with cathode ray tubes at the
University of Würzburg.
Because the nature of this radiation
was unknown, he named it “X-rays”,
with “X” meaning “unknown." For his
groundbreaking discovery, Röntgen
was awarded the first Nobel Prize in
Physics in 1901.
X-ray diffraction was discovered by “Max von
Laue” in 1912. he directed a beam of X-rays at
a crystal of zinc blende (ZnS) and recorded the
pattern produced on a photographic plate. They
observed a series of spots arranged in a
symmetrical pattern — this was the first X-ray
diffraction pattern, proving that ;
This experiment marked the birth of X-ray
crystallography / diffraction and earned Max
von Laue the Nobel Prize in Physics in 1914.

5. CONCEPT OF CRYSTALS ( SOLID )
Crystalline Solid : The solids that have their atoms, ions, or molecules which
are arranged in a definite three dimensional pattern are called as crystalline
solids.
Amorphous Solids OR Non – Crystalline Solid : The solids doesn’t have their
atoms, ions, or molecules are arranged in a definite three dimensional pattern
are called as Non - crystalline solids.
Poly - crystalline solids : This solids are materials composed of many small
crystals or grains, which are randomly oriented and joined together at grain
boundaries.

6. Crystalline solid Poly crystalline
solid
Amorphous solid or
Non - crystalline solid

7. SYMMETRY ELEMENTS PRESENT IN CUBIC
CRYSTAL
A) Plane of symmetry
Two types of plane of symmetry are possessed by cubic system.
1. Rectangular plane of symmetry
In this there will be two more such a planes hence there are three rectangular
plane of symmetry in all.
2. Diagonal plane of symmetry
In this Planes passing diagonally through the cube there are total 6 such planes
passing diagonally through the cube.

9. SYMMETRY ELEMENTS PRESENT IN CUBIC
CRYSTAL
B) Axis of symmetry
A. Four- fold axis of symmetry : One of the four fold axes is shown in the
figure (a) evidently there can be a total of 3 such four fold Axes are possible
passing through pair of opposite face centres parallel to cell axes
B. Three - fold axis of symmetry : One of the three - fold axes is shown in the
figure (b) evidently there can be a total of 4 such three – fold axes are possible
through cube body diagonals
C. Two - fold axis of symmetry : One of the two fold axes is shown in the
figure (c) evidently there can be a total of 6 such Two - fold axes are possible
passing through diagonal edge centre

10. (a) (b) (c)

11. SYMMETRY ELEMENTS PRESENT IN CUBIC
CRYSTAL
C) Centre of Symmetry
Only simple cubic system has one
centre of symmetry other system do
not have centre of symmetry it is
shown in the figure

12. PRINCIPAL
When a beam of monochromatic X-rays is incident on a crystalline material, the
atoms in the crystal lattice act as scattering centrrs . These scattered X-rays
interfere with each other, and constructive interference occurs.
only when the path difference between rays reflected from successive crystal
planes satisfies Bragg’s Law (nλ = 2d sinθ).
This produces a diffraction pattern that is characteristic of the crystal’s internal
structure.

14. COHERENT AND INCOHERENT WAVES
Coherent Light Waves
Coherent light waves are those that
share the same frequency.
Incoherent Light Waves
incoherent waves are characterized by
variations in phase, resulting in a lack
of consistent alignment among the
waves.

15. TYPE OF DIFFRACTIONS
Constructive Interference: When two
waves meet in phase (their crests and
troughs align), they combine to form a
wave with greater amplitude than
either original wave. This phenomenon
is called constructive interference. It
results in increased intensity of the
resultant wave.
Destructive Interference: When two waves
meet out of phase (crest of one falls on the
trough of another), they cancel each other
partially or completely, producing a wave
with reduced or zero amplitude. This is
known as destructive interference. It results
in decreased intensity, producing dark regions
or minima as seen in interference patterns.

16. ELASTIC SCATTERING
In a crystal sample we apply the X-rays which contain same energy
[0.5 Å to 2.5 Å ] in it the electrons inside the crystal will absorb the X-rays and
get excited and emits the same amount of x-ray with same energy back into
environment the emitted X-rays are called diffracted X - rays and the
phenomenon is called as elastic scattering.
Due to diffraction only angle of X-Ray is changes not the energy of rays.

17. INSTRUMENTATION OF XRD
An X-ray instrument contains three main items:
1. Monochromatic X-ray source
2. A sample holder or Goniometer
3. XRD Detector or Photographic Plate

18. COMPONENTS OF XRD INSTRUMENT
1. Monochromatic X-ray source : A monochromatic X-ray source emits X-rays of a
single, specific energy or wavelength
2. Goniometer: In XRD, a goniometer is a device that accurately positions and rotates a
sample relative to the X-ray beam and detector
3. XRD Detector :Scintillation counter detector orXRD detector is a main component of
an X-ray diffraction system, specifically designed to measure the intensity and position
of diffracted X-rays from a sample. This data is then used to analyse the sample's
crystallographic structure, phase composition, and other structural properties. Malvern
Panalytical's XRD detectors
(Photographic plates or XRD detector : XRD analysis, photographic plates were
historically used to record diffraction patterns, but have largely been replaced by electronic
detectors. )

21. INSTRUMENTATION OF XRD
The X-ray source produces monochromatic X-rays that illuminate the sample. This is
usually an X-ray tube, consisting of a tungsten filament (cathode) and a metal target
(anode), such as copper (Cu) . A high voltage (20–70 kV) accelerates electrons from the
cathode to strike the target, producing characteristic X-ray radiation. The generated X-rays
are collimated and conditioned using monochromators to obtain a narrow, parallel,
monochromatic beam, which is ideal for high-resolution diffraction.
The goniometer is the heart of the XRD instrument — it precisely controls the geometric
relationship between the X-ray source, the sample, and the detector. It holds the sample on
a sample holder and allows controlled rotation so that Bragg angles (θ and 2θ) can be
satisfied.

22. INSTRUMENTATION OF XRD
In powder XRD, the sample is usually finely ground and spread on a flat holder,
while for single-crystal XRD different sample mounts may be used. A motorized
system rotates the sample stage and detector simultaneously, enabling scanning
over a range of angles. Additional components like sample spinners or heaters
may be attached to maintain uniform orientation or control temperature.
As diffracted beams exit the sample, they are captured by a detector positioned at
the 2θ angle relative to the incident beam. Detectors convert incoming X-rays
into electrical signals.

23. HISTORY OF BRAGG’S LAW OF XRD
After the discovery of X-ray diffraction by Max von Laue in 1912, William Henry
Bragg and William Lawrence Bragg father and son duo investigated how X-rays reflect
off the atomic planes in crystals. They found that X-rays are reflected at specific angles
from parallel crystal planes, leading to constructive interference under certain
conditions. To explain this, W. L. Bragg formulated a simple relationship—now known
as Bragg’s Law:
nλ = 2 d sin θ
In recognition of their work, the Braggs jointly received the Nobel Prize in Physics in
1915.

24. BRAGG’S LAW OF XRD
Bragg’s law is a special case of diffraction, which determines the angles of
coherent and incoherent scattering from a crystal lattice. When X-rays are
incident on a particular atom, they make an electronic cloud move like an
electromagnetic wave.
When the X-ray is incident onto a crystal surface, its angle of incidence, θ,
will reflect with the same angle of scattering, θ. And, when the path
difference, d is equal to a whole number, n, of wavelength, constructive
interference will occur.

26. BRAGG’S LAW OF XRD
nλ = 2 d sin θ
n = order of diffraction (an integer: 1, 2, 3,…)
λ = wavelength of the incident X-ray
d = distance between the two successive planes in crystal
Θ = angle of incidence

27. TYPE OF XRD TECHNIQUES
1. Powder X-ray Diffraction (PXRD)
2. Single-Crystal X-ray Diffraction (SCXRD)
3. Laue (Single Crystal Laue Diffraction)
4. Small-Angle X-ray Scattering (SAXS)

28. APPLICATIONS OF XRD
• Determination of unit cell dimensions.
• Differentiation between crystalline and amorphous materials.
• Determination of the texture of polygrained ( poly - crystalline) materials.
• Determination of orientation of single crystals.
• Determination of electron distribution within the atoms and throughout the
unit cell.
• Pharmaceutical Applications : Distinguishing polymorphs, analysing purity
and stability of drug crystals.
• Biological Macromolecules Single-crystal XRD applied to proteins, DNA,
enzymes to understand biological structure and function.

29. ADVANTAGES OF XRD
• Identification of crystalline phases in unknown materials.
• Determination of crystal structure and lattice parameters of solids.
• Measurement of crystallite (grain) size and microstrain using peak broadening.
• Quantitative phase analysis in multi-component mixtures (e.g., ores, cements).
• Analysis of thin films and coatings, including thickness, stress, and preferred
orientation (texture)

30. LIMITATIONS OF XRD
• Requires crystalline materials, amorphous substances give poor diffraction
patterns.
• Sample preparation must be precise
• Cannot easily detect low-concentration phases, minor phases below ~1–3%
may go undetected.
• Peak overlap can make complex mixtures difficult to interpret.
• No direct information on chemical bonding or oxidation state, only geometric
arrangement is determined.

31. THANK YOU