X-ray Diffraction (XRD)

Working principle & Instrumentation 

XRD instrumentation 

XRD (X-ray Diffraction) is versatile nondistructive technique used to analyze the crystallographic structure of materials by measuring the diffraction pattern of X-rays as they interact with a crystalline 

sample.

XRD provides information about crystal structure, lattice parameters, phase composition, and preferred orientation of crystallites in a sample. Many materials are made up of tiny crystallites the chemical composition and structural type of these crystals is called their phase materials can be single phase or multiphase mixture and may conatin crystalline and non cryastalline components. In an X-ray diffracto meter different crystalline phases gives different diffraction patterns. Phase identification can be perform by comparing X-ray diffraction patteren obtained from unknown samples to patterens inreference data base. In XRD atoms of the sample donot absorb X-ray at all they just reflect them .if we did not get any peak in the material its mean the material 

is amrophous other vice it will be crystalline.

The XRD instrument consists of an X-ray tube, a sample holder, a crystal monochromator or a diffracting crystal, and a detector. The instrument used to maintain the angle and rotate the sample is termed a goniometer. The X-ray beam interacts (constractive interference) with the sample and the diffracted X-rays are detected to generate a diffraction pattern. The wavelegth of X-ray used is of the same order of magnitude of the distance between the atom in crystalline lattice. This gives rise to a diffraction pattern that can be analysied by number of ways usually sherrer equation D=Kλ/βcosϴ is used for crystalline size determination D=crystallite size K=0.9 (scherrer constant) λ= 0.15406nm (wave length of X-ray source) β=FWHM(in radians) ϴ= peak position (in radians) Bragges law nλ=2dsineϴ d= nλ/2sineϴ d= interplaner spacing or d spacing (in Ǻ) is used for mesurement of interplaner spacing or d spacing.

Sample Preparation Samples should be finely powdered and homogenously dispersed to ensure representative results. Amorphous materials may not produce diffraction patterns, as XRD is most effective for crystalline samples.

Results Interpretation XRD results are typically presented as a diffraction pattern, where peaks correspond to specific crystallographic planes. The position and intensity of these peaks provide information about the crystal structure and phase composition of the materialPeak width is inversly proportion to crystal size.

XRD graph