Why XRD? 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.
X-ray crystallography is the experimental science determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to diffract into many specific directions
X-ray diffraction (XRD) helps to find the geometry or shape of a molecule using X-rays. The elastic scattering phenomenon of X-rays from the atoms of material has a long range order.
X-Ray Diffraction (XRD) types:
- Micro (µXRD)
- Parallel Beam XRD.
- Parallel Beam XRD for Powder.
- Parallel Beam XRD for Stress.
- Parallel Beam XRD for Crystal.
- Parallel Beam XRD for Texture.
- Protein Crystallography.
- Neutron Diffraction.
XRD Peak:
Peak intensity tells about the position of atoms within a lattice structure. and peak width tells about crystallite size and lattice strain.
X-ray diffraction (XRD) is one of the most extensively used techniques for the characterization of NPs. Typically, XRD provides information regarding the crystalline structure, nature of the phase, lattice parameters and crystalline grain size.
Brag Equation :
n λ = 2 d sin θ where λ is the wavelength of the radiation used, d is the inter-planar spacing involved and θ is the angle between the incident (or diffracted) ray and the relevant crystal planes; n is an integer, referred to as the order of diffraction, and is often unity.
Energy Range :
X-rays have photon energies in the range 100ev - 100Kev. In structural characterisation, mainly short wavelenght x-rays are used, with a range of 10>0.1 angstoms.
Peak Match
After having the data for unknown phase one can proceed to match the 'd' value of the strongest reflection in the experimental pattern available in the database. After proper matching of the first 'd' value of the most intense peak, the second and third intense reflections are matched to the closest 'd' values.
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