Nukleasjonskilde

Nukleasjonskilde, or nucleation site, refers to a specific location where a phase transition, such as crystallization or boiling, can begin. In a homogeneous substance, nucleation typically requires overcoming an energy barrier to form a stable nucleus of the new phase. However, a nukleasjonskilde lowers this energy barrier, making the transition more likely to occur at that point. These sources can be naturally occurring or deliberately introduced.

In the context of boiling, a nukleasjonskilde is often a microscopic imperfection on a heating surface, such as a scratch, crevice, or trapped gas bubble. These imperfections provide surfaces where vapor bubbles can form and grow more easily than in the bulk liquid. Without these sites, a liquid might become superheated, meaning its temperature rises above its boiling point without boiling.

In crystallization, a nukleasjonskilde can be impurities, dust particles, or even rough surfaces within the solution or melt. These foreign bodies provide a template or surface energy reduction that facilitates the ordered arrangement of molecules into a crystal lattice. Homogeneous nucleation, where the new phase forms spontaneously without a nukleasjonskilde, requires significantly higher degrees of supersaturation or supercooling. Therefore, the presence of effective nukleasjonskilder is crucial for many practical applications, including industrial processes, material science, and even biological phenomena like ice formation in cells.