X-ray diffraction patterns provide a unique fingerprint for crystalline substances. When X-rays strike the planes of atoms within a crystal, they cause diffraction according to Bragg's law. Bragg's law states that constructive interference of X-rays occurs when the path length difference between X-rays reflected from successive planes is equal to an integer multiple of the wavelength. This relationship is expressed by the equation nλ = 2d sinθ, where d is the spacing between atomic planes, θ is the incident angle, n is an integer, and λ is the wavelength of electromagnetic radiation. X-ray diffraction analysis can be used to determine properties of crystalline materials such as crystal structure, orientation, and stress.

1. Principle Of X-Ray Diffraction
PRESENTED BY;
Aiswarya. A.T.,
I year M.Pharm.,
Dept. of Pharmacy Practice,
Grace College of Pharmacy

2. X – Ray Diffraction
“ Every crystalline substance gives a pattern; the same
substance always gives the same pattern; & in a mixture of
substances each produces its pattern independently of the
others”
The X-ray diffraction pattern of a pure substance is,
therefore, like a fingerprint of the substance. It is based on
the scattering of x-rays by crystals.
Definition : The atomic planes of a crystal cause an
incident beam of X-rays to interfere with one another as
they leave the crystal. The phenomenon is called X-ray
diffraction

3. Principle

5. Bragg’s Law and Diffraction
William Henry Bragg
Diffraction occurs only when Bragg’s Law is satisfied
Condition for constructive interference (X-rays 1 & 2)
from planes with spacing d
Xray
1Xray 2

6. Constructive
interference
X-ray 2 occurs
only when,
n ƛ = AB + BC
AB=BC
n ƛ = 2AB
Sin θ =AB/d
AB=d sin θ
n ƛ =2d sin θ
ƛ = 2 d sin θ
AB+BC = multiples of n ƛ
Xray 1
Xray 2

7. Measure the average spacing's between layers
or rows of atoms
Determine the orientation of a single crystal or
grain
Find the crystal structure of an unknown
material
Measure the size, shape and internal stress of
small crystalline regions
Why XRD???

8. Thank U !!!