X-ray diffraction (XRD)
• Introduction
• Basic Principle
• Applications
• XRD of Activated Carbon
• XRD of Carbon black
• Instrumentation
• Advantages and Disadvantages of XRD
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X-ray diffraction (XRD)
Introduction
• A technique used in materials science to determine the crystallographic
structure of a material. XRD works by irradiating a material with incident X-
rays and then measuring the intensities and scattering angles of the X-rays
that leave the material.
• A versatile non-destructive analytical technique used to analyze physical
properties such as phase composition, crystal structure and orientation of
powder, solid and liquid samples. Many materials are made up of tiny
crystallites.
• XRD finds the geometry or shape of a molecule using X-rays.
• XRD techniques are based on the elastic scattering of X-rays from
structures that have long range order. The X-rays get diffracted by a crystal
because the wavelength of X-rays is similar to the inter-atomic spacing in
the crystals
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Basic Principle of X-ray diffraction (XRD)
X-ray analysis of atomic structural arrangements relies on diffraction
phenomenon where waves interact with system, known as diffracting centers,
spaced at a distances comparable to the wavelength of radiation.
The most prevalent type of diffraction to X-ray crystallography is known as
Bragg diffraction Which defined as the scattering of waves from crystalline
structure. The relationship describing the angle at which a beam of x-ray of
particular wavelength diffracts from crystalline surface was discovered by Sir
William H. Bragg and Sir William Lawrence Bragg is known as Bragg’s Law.
nλ = 2d sin θ
Where λ =Wavelength of x-ray
n= inter representing the order of diffraction peak 0,1,2,3
θ = Scattering angle; d= integer plane distance of (atoms, ions,
molecules)
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X-ray diffraction (XRD) Analysis Technique
• X-ray diffraction analysis technique is nondestructive technique to find out the
crystallographic structure , chemical composition and physical properties of
the substances.
• Based on constructive interference of monochromatic x-ray.
• In this technique the generated x-rays are paralleled and directed to the
sample.
• During this process the interaction of incident rays with sample results the
diffraction of x-ray.
• The diffracted rays are then detected ,processed and counted.
• XRD is done to examine the crystallinity of nanomaterials
Applications of X-ray diffraction (XRD)
• To analyze the crystallinity , structure ,properties and phase composition of
materials.
• For identification of unknown of crystalline substance with respect to
reference.
• To test the purity of and quality of crystalline substance.
• XRD spectra –used for calculation of percentage crystallinity of substance.
• XRD –used to determine grain size particles.
• Used to measure the size of nanoparticles. 4
XRD of Activated Carbon
Broad Peaks
Broad Peaks
Broader peaks observed means that there may be a smaller crystal, defect in
the crystalline structure, or that the sample might be amorphous in nature, a
solid lacking perfect crystallinity.
XRD of ACs exhibits their features with prominent peak at about 2Ѳ = 25 ° and
44°, respectively 5
XRD of Carbon black
XRD patterns of the sample in which narrow and sharp peaks indicating good
crystalline characteristics of the samples
If a sharp peak is observed, it indicates the crystalline nature.
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Instrumentation XRD
• Radiation Source
• Monochromator
• Sample handling
• Detector
• X-ray diffraction device
X-ray Diffraction Instrumentation
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Advantages of XRD
• One of the main advantages of XRD is its non-destructive nature, allowing for
the analysis of materials without the need for destructive sample
preparation .
• XRD also enables the determination of the mineralogical composition and
crystalline structure of materials, providing valuable information for process
control and material characterization .
• Additionally, XRD methods, such as diffraction with synchrotron radiation,
allow for selective measurements of specific alloy phases, enabling the
independent investigation of each phase's behavior .
Disadvantages of XRD
• It cannot produce real-space images of materials like electron microscopy due
to the lack of suitable lenses .
• Furthermore, high-resolution XRD setups with one-dimensional detectors
may sample only a small portion of the Debye rings, limiting the accuracy of
structure factors .
• Despite these limitations, XRD remains a valuable technique for the analysis
of materials in various fields .
Debye-Scherrer rings" are concentric diffraction rings produced by Bragg reflections,
which are obtained when polycrystalline thin films are illuminated with a highly parallel
electron beam. 8
Non-destructive tests (NDT) are methods that do not damage the parts being
tested.
