What is the Difference Between Grain Size and Crystallite Size

The key difference between grain size and crystallite size is that grain size is the diameter of individual grains of sediment or lithified particles in clastic rocks, whereas crystallite size is the size of a single crystal inside a particle or gain.

Grain size and crystallite size are important factors regarding solid materials. They have different definitions, measurement methods, as well as parameters.

1. Overview and Key Difference
2. What is Grain Size
3. What is Crystallite Size
4. Grain Size vs Crystallite Size in Tabular Form
5. Summary – Grain Size vs Crystallite Size

What is Grain Size?

Grain size can be defined as the diameter of individual grains of sediment or lithified particles in clastic rocks. This term describes other granular materials as well. An individual grain may contain several crystals, and granular substances typically range from very small colloidal particles to clay, silt, sand, gravel, and cobbles, to boulders.

The methods that can be used to determine the grain size include mesh scale, optical granulometry, sieve analysis, and soil gradation. Moreover, we can define the size ranges from names given in the Wentworth scale that is used in the USA. In 1934, W.C. Krumbein used a modification of the phi scale known as the Wentworth scale, which is a logarithmic scale that gives a way to determine the diameter.

Moreover, we can sort out an accumulation of sediment that is characterized by the grain size distribution. Typically, a sediment deposit undergoes this sorting out upon the removal of particle size range by another source such as river or wind. It is possible to quantify this sorting using the Inclusive Graphic Standard Deviation.

What is Crystallite Size?

Crystallite size can be given as the smallest and most likely single crystal in powder form. Typically, this parameter is determined using X-ray diffraction. In 1918, Scherrer derived a formula that relates the mean crystallite size given by L of a powder to the broadening of the diffraction peaks of the powder.

Generally, the crystallite size is an important parameter because the sizes of the crystals determine the softness or the brittleness of a material (usually, the small crystallites are soft, and large crystallites are brittle). Moreover, the thermal and diffusion behaviours of polymers that are semicrystalline can be determined as well.

Generally, the term crystallite size refers to nanopowders, colloids, gels, and spray-dried agglomerates. If the crystallite size is smaller, the sintering is more efficient, but the shrinkage due to drying and keeping in the fridge can still be very high.

According to some research studies, crystallite size corresponds to the coherent volume in the material concerning the respective peak of diffraction. Sometimes, it can refer to the size of the grains of a sample of powder as well as the thickness of polycrystalline thin films and bulk material.

What is the Difference Between Grain Size and Crystallite Size?

Grain size and crystallite size are two factors measured in a solid material. The key difference between grain size and crystallite size is that grain size is the diameter of individual grains of sediment or lithified particles in clastic rocks, whereas crystallite size is the size of a single crystal inside a particle or gain. Therefore, the defining factor of grain size is the diameter, whereas the defining factor of crystallite size is the dimensional size.

The below infographic presents the differences between grain size and crystallite size in tabular form for side-by-side comparison.

Summary – Grain Size vs Crystallite Size

The key difference between grain size and crystallite size is that grain size is the diameter of individual grains of sediment or lithified particles in clastic rocks, whereas crystallite size is the size of a single crystal inside a particle or gain.