X-ray Diffraction Analysis (XRD)

Introduction to X-ray Diffraction Analysis (XRD)

X-ray diffraction (XRD) is a versatile analytical technique used to analyze physical properties such as phase (chemical composition and structural type), crystal structure and orientation of powder in solid and liquid samples in a non-destructive manner. Materials may contain crystalline and non-crystalline components and can be single phase or multiphase mixtures. XRD is a common technique that determine a sample’s composition or its crystalline structure. For larger crystals such as macromolecules and inorganic compounds, XRD can be used to determine the structure of atoms within the sample. If the crystal size of a sample is too small, XRD can determine sample composition, crystallinity, and phase purity. This technique sends x-ray beams through it.

XRD utilizes the constructive interference of monochromatic X-rays and a crystalline sample. X-rays are shorter wavelength electromagnetic radiation that are generated when electrically charged particles with sufficient energy are decelerated. X-ray diffraction analysis is used in testing labs of many industries such as geology, metallurgy, chemistry, pharmaceuticals, and materials science.

Principle and Methodology of X-ray Diffraction Analysis (XRD)

The principle behind XRD is based on Bragg’s Law which states that when an incident X-ray beam strikes a crystal lattice at a particular angle, some of the rays are reflected off the lattice planes at an angle equal to that of the incident beam. These diffracted rays are then detected, processed, and counted in testing labs. The intensity of the diffracted rays scattered at different angles of material are plotted to display a diffraction pattern using special software to generate a diffractogram which displays peaks corresponding to different lattice planes in the sample material. The position and intensity of these peaks can be used to determine the structure of the sample material.

X-ray diffraction is the result of constructive interference between X-rays and a crystalline sample.The reflected rays form an interference pattern which can be used to determine the spacing between lattice planes in the crystal and hence its structure. This interference pattern obtained can also be used to identify unknown substances by comparing it with stored patterns obtained from known substances.

The instrumentation in XRD analysis includes an X-ray source such as an X-ray tube or synchrotron radiation source; detectors such as photographic plates or scintillation counters; sample holders; computers; and special software for analyzing data collected from experiments.

Uses of X-ray Diffraction Analysis (XRD)

X-ray diffraction (XRD) analysis has many applications in various fields such as mineralogy, geology, pharmaceuticals, metallurgy and materials science. XRD is utilized  for identification and characterization of different substances as well as determining their physical properties such as crystallite size and strain distribution. Additionally, this technique can also be used for quality control purposes in industries such as pharmaceuticals or food production by detecting impurities or defects in products invisible under normal conditions. 

Advantages of X-ray Diffraction Analysis (XRD)

XRD provides information about phase composition, crystallite size and strain in materials which can be useful for quality control purposes. One major advantage of using XRD analysis is its ability to detect even small amounts of impurities or defects in materials that may not be visible under normal conditions. Additionally, samples do not require any special preparation or treatment before analysis making it easy to use for most applications.

Disadvantages of X-ray Diffraction Analysis (XRD)

There are some disadvantages associated with XRD technique such as (a) high cost due to expensive instrumentation required for performing experiments, (b) its limited range since it cannot analyze samples larger than 10 microns, and (c) its sensitivity which makes it difficult to analyze samples with low concentrations or low diffracting powers such as polymers or biological samples. Also, this technique requires highly trained personnel who are knowledgeable about operating complex equipment which may not always be available in certain laboratories or industries.