Particle (materials science)
A particle is a discrete fragment of solid or liquid matter, often suspended in a fluid or assembled with other particles into a granular material.
Particle size: A measure of the dimensions of an individual particle or a population of particles. Size affects settling, packing, reactivity, and how particles are classified.
Brownian motion: Random motion of small particles suspended in a fluid, caused by molecular collisions. It dominates the transport of sufficiently small particles in liquids and gases.
Laser diffraction analysis: A particle-sizing method that infers size distributions from the angular pattern of scattered laser light. It provides rapid size distributions for powders, suspensions, and emulsions.
Molecule: An electrically neutral group of atoms held together by chemical bonds. A material particle is usually a larger fragment, though particles can be molecular in some contexts.
Particle shape: The geometry and surface form of an individual particle. Shape influences packing, flow, and contact between particles.
Sedimentation: The movement of suspended particles through a fluid under gravity or another body force. Particle size, density, and fluid viscosity set the settling rate.
Dynamic light scattering: A method that estimates sizes of small suspended particles from fluctuations in scattered light. It is widely used to characterize nanoparticles in liquid dispersions.
Grain (materials science): A region within a crystalline solid whose crystal lattice has a uniform orientation. A grain is an internal crystal domain, not necessarily a separate fragment of matter.
Particle size distribution: A description of the relative amounts of particles across different size ranges. Real materials contain size ranges, not just one representative particle size.
Particle aggregation: The joining of particles into larger clusters through physical or chemical interactions. Aggregation changes effective size and can alter suspension stability.