The Gibbs-Thomson effect
(also called the Gibbs-Kelvin effect or Kelvin effect) relates surface curvature
to vapor pressure
and chemical potential
. It is named after Josiah Willard Gibbs
and William Thomson, 1st Baron Kelvin
. (It is not to be confused with the thermoelectric Thomson effect
It leads to the fact that small liquid droplets (i.e. particles with a high surface curvature) exhibit a higher effective vapor pressure, since the surface is larger in comparison to the volume. The Gibbs-Thomson effect can cause strong depression of the freezing point of liquids dispersed within fine porous materials.
Another notable example of the Gibbs-Thomson effect is Ostwald ripening, in which concentration gradients cause small precipitates to dissolve and larger ones to grow.
The Gibbs-Thomson equation for a precipitate with radius is:
- : Atomic volume
- : Boltzmann constant
- : Surface tension (J m)
- : Equilibrium partial pressure (or chemical potential or concentration)
- : Partial pressure (or chemical potential or concentration)
- : Absolute temperature
Ostwald ripening is thought to occur in the formation of orthoclase megacrysts in granites as a consequence of subsolidus growth. See rock microstructure for more.