X-Ray Diffraction - Crystal Structure

It’s useful for studying Crystal structure

This method have the details about

• Grain size (or) Crystal size
• Orientation of the crystal
• Cold worked, Distorted and Internally stressed crystals
• Re-Crystallization
• Preferred orientation etc

Methods of Examining and Measuring the condition of Crystal Structure

1. The Laue back reflection method
2. The Rotating Crystal method
3. The DeBye- Scherrer (or) Powder method:

The Laue back Reflection method:
It’s applicable to single crystals (or) poly-Crystalline masses.
When a beam of Mono chromatic (i.e. of Single Wavelength) X-Ray is directed as a narrow pencil at a specimen of a metal diffraction takes place at certain of the crystallographic planes.
 

       

The Rotating Crystal method:
It’s a useful method for determining angles and positions of planes.
Crystallographic planes are brought in to reflecting positions by rotating a crystal (Specimen) about one of it’s axis while simultaneously radially it with a beam of mono chromatic x-Rays.
If crystal orientation planes are known, the angles and directions can be calculated.


The DeBye- Scherrer (or) Powder method:
The narrow pencil of monochromatic X-Rays is diffracted from the powder and recorded by the photographic film as a series of lines of varying armature.
By the Bragg Equation:

nλ=2d Sinθ

Where,

λ– Wave length of X-ray

d- Spacing of the atomic planes

θ – Angle of reflection