Best Information of X-Ray Diffraction

X-Ray Diffraction what it is? Does X-Ray Diffraction is a good technique for the identification of material structure?

XRD machine
X-Ray Diffraction machine
Today we are in the 21st century and day by day techniques are going to develop. But nowadays X-Ray Diffraction (XRD) is a widely used technique for identification for crystalline aggregate in pharmaceutical as well as various industries. Same if we will think about the Identification test in pharmaceutical, earlier we are using UV-visible, IR, mass spectroscopy instruments for identification.  


Electromagnetic spectrum
Electromagnetic spectrum for X-Ray Diffraction

 Here we will learn about below-mentioned topics:

  1. What is X-Ray Diffraction (XRD)
  2. Principle of XRD
  3. Bragg’s equation of XRD
  4. Application of XRD

1.What is X-Ray Diffraction (XRD)?

From the last decade, XRD is a widely used technique for structural elucidation of material in various industries like Pharmaceutical, chemical, biochemical, mineral, fiber, fluid, powder, crystals, metals, etc.

An X-ray diffractometer is a machine where we identify the chemical and physical properties of the material with the help of an X-ray.

X-Ray Diffraction (XRD) is nondestructive qualitative technique to identify the physical property, chemical composition and crystallographic structure of material. XRD plays critical role to identify the material which is not available in single crystal form.


X ray 2Bdiffraction
X-Ray Diffraction

XRD is an essential technique for 

  1. Identification of crystalline compound
  2. Quantitative analysis of polyphasic mixtures
  3. To study the long-range atomic structure of the crystal
  4. Physical analysis of crystalline aggregate (texture, size, lattice Microstrain)
XRD is a phenomenon by which X-rays are reflected by atoms in a crystalline solid is called diffraction. XRD is the elastic scattering of X-ray photons by atoms in a periodic lattice. The diffracted rays show a pattern of the structural orientation of each atom available in the compound. To better understand of what is elastic scattering here is the best example.

An ocean wave striking a lighthouse produces secondary circular waves emanating from the lighthouse, so an X-ray striking an electron produces secondary spherical waves emanating from the electron. This phenomenon is known as elastic scattering, and the electron (or lighthouse) is known as the scatterer.

2.What is Principle of XRD:

XRD analysis is based on constructive interference of monochromatic X-Ray and a crystalline sample: X-Rays are generated by the cathode ray tube are filtered to produce monochromatic radiation, rays accurately parallel to concentrate, and directed towards to the sample. 

XRD detects and shows a shape and molecular size of an atom present in the compound. In short, XRD determines the atomic and molecular structure of crystals.

3. Bragg’s Equation of XRD:

When a sample is analyzed through the XRD instrument the X-rays are passes (Incident beam) through the sample, some rays are transfers and some are making an angle of reflection. The reflected rays are called diffracted rays. The X-rays are recorded in the XRD instrument and the angle of diffraction is measure through Bragg’s equation.
In 1913 this equation is introduced by English physicist Mr. W.H. Bragg and his son Mr. W.L. Bragg to explain why the cleavage face of crystals appears to reflects X-ray beams at a certain angle of incidence (theta). For this theory, Mr. Bragg’s are awarded by Nobel prize in 1915.
Bragg’s Equation:
n- is Denotes for integer
λ- is Denotes for the wavelength of the beam
d- is denotes for spacing between two diffracting planes
θ- is Denotes for an incident of beam


Bragg's equation


Bragg's Equation
Bragg’s Equation

4. Application of XRD:

  1. XRD is widely used for characterisation of crystalline material
  2. XRD is useful to determine the physical properties of a molecule like size, lecture, lattice
  3. Determination of unknown solid which is critical to studies in geology, material science, engineering, biology, and environmental science
  4. Make a textual measurement such as the orientation of grains in a polycrystalline material.

Strength and limitation of XRD:

Strength of XRD:

  1. Minimum sample required for analysis
  2. A powerful and rapid technique for identification of the powdered material
  3. Data interpretation is relatively straight forward
  4. XRD is widely available

Limitations of XRD:

  1. For mixed material detection limit is 2% of the sample 
  2. Homogeneous and single-phase material is best for the identification of unknown material.
  3. Peak overlay may occur and worsen for a high angle of reflection. 
  4. For amorphous solid xrd will give a hump-like spectrum.
Amorphous spectrum
Amorphous spectrum

For More Details: 

Refer: 21 CFR Part 1020, Subchapter J– Radiological health

Refer: Section 1020.40 –Cabinet X-Ray system

Production of X-Ray Diffraction
Production of X-Ray Diffraction

Also Read:

Refer YT Channel: Pharmabeej