Crystallite Size ≤ Grain Size ≤ Particle Size Explained | TEM vs XRD

Understand the exact size relationship between crystallite, grain, and particle dimensions using TEM and XRD.
This clear hierarchy — Crystallite ≤ Grain ≤ Particle — shapes how we analyze nanomaterials in research and industry.

Understanding the size hierarchy Crystallite ≤ Grain ≤ Particle is essential in materials science, nanotechnology, and electron microscopy workflows. This video breaks down the key differences in how crystallite size, grain size, and particle size are defined and measured, and explains why XRD and TEM often give different results.

Crystallite Size:
A crystallite is the smallest coherent crystalline domain within a material. XRD (X-ray diffraction) can estimate crystallite size using the Scherrer equation, based on peak broadening in the diffraction pattern.

Grain Size:
A grain consists of one or more crystallites. Grains merge to form the microstructure of a material. TEM (Transmission Electron Microscopy) and SEM-based EBSD are commonly used to measure grain size directly.

Particle Size:
A particle is a larger agglomerate made of multiple grains or crystallites. Particle size measurements come from TEM, SEM, DLS, or image analysis.

This explanation is essential for researchers working in nanomaterials, thin films, ceramics, catalysts, and semiconductor materials. The video also clarifies why particle size ≥ grain size ≥ crystallite size, and how to match XRD and TEM results correctly.

If you work in materials synthesis, microscopy, nanotechnology, or characterization, this comparison will help you avoid common mistakes and interpret your data with confidence.

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