Particle size refers to the overall size of the individual particles in a material, while crystallite size specifically refers to the size of the crystalline regions within a material. Crystallite size is related to the arrangement of atoms within a material, while particle size is a more general measure of the physical dimensions of the particles.

Crystallites are small, often microscopic crystals that, held together through highly defective boundaries, constitute a polycrystalline solid. Metallurgists often refer to crystallites as grains.

Crystallite glass is a type of glass that has small crystals or crystalline structures embedded within it. This gives the glass a unique sparkling or shimmering effect when light passes through it. It is often used in decorative objects or jewelry to add an extra element of visual interest.

XRD (X-ray diffraction) is a technique used to analyze the crystallographic structure of materials. It provides information on the crystal structure, phase composition, and crystallite size of a sample, helping to identify the different phases present in the material and their arrangement in the crystal lattice.