Single Crystal XRD Vs Powder XRD

Types of X-rays diffractions (XRD) Analysis:

There are basically four (04) types of XRD analysis

1. Single Crystal XRD
2. Powder XRD (pXRD)
3. Small-Angle X-ray Scattering. (SAXS)
4. Grazing Incidence X-ray Scattering (GIXS)

However, I will only explain about the single crystal XRD and pXRD

Let's first discuss the single crystal XRD technique.

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Single Crystal XRD Analysis:

Single-crystal XRD uses to characterizes a sample of single well-ordered and high-quality crystals

The sample must be crystalline in nature, i.e., single crystal (single crystal is any solid substance in which the atoms, ion, or molecules are arranged in order and repeated throughout the whole volume.

This technique yields more information compared to other XRD techniques. however, growing high-quality single crystals is difficult.

The diffraction data is distributed in 3D space, where individual intensity of the spots is measured.

Applications (Uses) of single crystalline XRD:

Determine the position of the atoms
Crystallographic information
Unit cell dimensions
inter-planar spacing
symmetry identification
Nature of bonds
Bond angle

Now, let's discuss the powder XRD (pXRD) technique.

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Powder XRD (pXRD) technique

The pXRD characterizes the nanomaterials that exist in a powder form. This is the common technique as most of the samples are in the form of powder form.

The sample should be dry and should be in powder form.

Comparatively collect less information than the single crystalline XRD.

It is quite easier to produce a powder form of any sample

The diffraction data in this case are “compressed” into 1D. Basically, each spot from the same (hkl) overlaps and makes profile intensity.


Applications (Uses) of pXRD Analysis:

Phase (polymorph) identification
Crystallinity of the material
Unit cell dimensions and d- spacing.
Calculation of average grain size or particle size using Scherrer’s formula.
Strain information

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Question: What is Phase in XRD analysis?

Answer: A phase is a crystalline solid structure with a regular 3D arrangement of the atoms. For instance, TiO2 may exist in two forms or phases, such as cubic or Tetragonal. Similarly, other materials may exist in hexagonal or monoclinic.

Question: How to identify the Phase in XRD analysis?

Answer: The diffraction peaks positions and intensities in the measured XRD pattern considered a "fingerprint" for a given material and for a particular crystalline phase. The peaks positions are compared with databases and the phase identified.