The dark band results due to destructive interference and the bright bands due to constructive interference between waves. If the set of evenly placed slits or periodic structures is used, the scattered X-rays interact with each other resulting in the formation of a series of bright and dark bands or fingers or patterns. This phenomenon of X-rays is called diffraction. When X-rays are passed through a narrow slit or obstructed by a small obstacle, they spread out or bend around the edges. It is also important to note that X-ray diffraction provides only an average crystallite size. Where, k = Scheerer’s constant whose value for spherical crystal is around 0.9, λ = wavelength of X-ray used, θ = diffraction angle, = full width at half maximum intensity (in radian) of the intensity profile. Moreover, the size of the particle or average grain is estimated using XRD by using Scheerer’s formula: Where d is the interplanar distance and λ is the wavelength of the X-rays. According to Bragg’s equation, “When an x-ray strikes a crystal surface, its angle of incidence, θ, reflects back with the same angle of scattering, θ, and leads to constructive interference when the path difference, d, is equal to a whole number, n, of wavelengths”. Bragg explained this phenomenon to calculate interatomic distances from X-ray diffraction patterns. ![]() The phenomenon is known as X-ray diffraction. It also determines the orientation of a single crystal or grain, measures the size, shape, and internal stress of small crystalline regions, and measures the average spacing between layers or rows of atoms.Īn incident beam of X-rays interacts with one another as it exits a crystal due to its atomic planes. It provides chemical information for both phase analysis and elemental analysis and helps to find the geometry of molecules ( nanomaterials) using X-rays. ![]() X-ray Diffraction (XRD) is a non-destructive analytical technique used to extensively characterize the crystal structure of solids, defects, and stresses.
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