Diffusion constant

The diffusion constant (also known as the diffusion coefficient under ideal conditions) is a substance-specific parameter that indicates how quickly a substance diffuses into a specific medium. It is expressed in m²/s and depends on the temperature, the density of the medium and the molecular properties of the diffusing substance. In powder processing, it is particularly important for moist or gas-laden powders, e.g. during drying or aroma release.

Diffusion in solids is also relevant when heterogeneous solids are dispersed and sintered in a nanodisperse state.

For diffusing gases, the formula for the diffusion coefficient given in the glossary applies approximately.