How Peak Position Identify Crystal Structure :: XRD Analysis

This video explain the importance of Peak position: (The x-axis values) in XRD spectrum.

Peak position i.e., diffraction angle (2θ) is a function of
1. Crystal structure
2. Unit cell parameters (a, b, and c,)
3. Distance between reflection planes (dhkl)

From Bragg's law, the peak position can be calculated theoretically

λ = 2dsinθ or d = λ/2Sinθ

The peak position determine the “crystal structure” because difference in crystal structure effects the peak’s position!!

For unit cell, the lattice parameters can be calculated
d = a/√(h^2+k^2+l^2 )

For (100) reflection
a= d √(h^2+l^2+k^2 )

So knowing miller indices (hkl) of any reflection and dhkl! we can find a, b and c for SC, BCC, and FCC…crystal structure!

To know the lattice type we need only the position of the peaks