XRD principle

An X-ray diffractometer consists mainly of 4 elements: an X-ray tube, a sample holder, an X-ray detector and a Goniometer.


The Atomic Level

1- All atoms have a fixed number of electrons. These electrons are arranged in orbitals around the nucleus.

2- These electrons are arranged in orbitals around the nucleus. XRF dispersive energy (EDXRF) typically works on activity in the first three electron orbitals, the K, L and M lines.

3- The primary photons of the X-ray tube have sufficient energy to pull electrons out of the innermost orbitals, creating a vacancy (1). An electron from an external orbit will move into the newly vacant space at the internal orbit to regain stability in the atom (2).

4- When the electron of the outer orbit moves into the internal orbit, it releases energy in the form of a secondary X-ray photon.

Filtering is required to produce the monochromatic X-rays necessary for diffraction. Copper is the most commonly used target material for monocrystalline diffraction. These X-rays are collimated and directed on the sample. During rotation of the sample and the detector, the X-ray intensity is collected as peaks in a spectrum. When the incident X-ray geometry interacting with the sample satisfies the Bragg equation, interference occurs and causes a particular peak of intensity. The X-Rays detector and a signal processing chain converts it into a counting rate which is then used by a data processing and display software.

The mechanical system of an X-ray diffractometer is designed so that the sample rotates in the path of the X-ray beam collimated at an angle while the X-ray detector is mounted on an arm to collect X-ray diffracted X-rays. rotating with 2θ angle. This assembly that holds the angle while swiveling the sample is a goniometer.

Pour To maintain these performances while being sufficiently miniaturized to be portable, it is possible to use a montage based on the Seemann-Bohlin focusing geometry.

X-Ray Diffraction (XRD) is an analytical technique used for the phase identification of crystalline materials, often used for mineralogical and geological studies.