Nucleációval

Nucleációval, or nucleation in English, is the initial stage of a phase transition where a new thermodynamic phase forms within a metastable parent phase. This process is fundamental to many natural phenomena and technological applications, including crystallization, boiling, and precipitation. For nucleation to occur, a small cluster of the new phase, known as a nucleus, must form spontaneously. This initial nucleus is typically unstable due to surface tension effects, which cost energy. However, if the nucleus grows beyond a critical size, the bulk free energy gained by forming the new phase overcomes the surface energy cost, making further growth energetically favorable.

There are two primary types of nucleation: homogeneous and heterogeneous. Homogeneous nucleation occurs spontaneously within the parent phase without the influence of any foreign surfaces or impurities. It requires a greater degree of supersaturation or undercooling to overcome the energy barrier. Heterogeneous nucleation, on the other hand, occurs at pre-existing surfaces, such as container walls, defects, or impurity particles. These surfaces provide sites where the formation of the new phase is energetically less demanding, thus reducing the critical size and facilitating nucleation at lower degrees of supersaturation or undercooling. The rate of nucleation is highly dependent on temperature, pressure, and the presence of nucleating agents. Understanding nucleation is crucial for controlling the size, shape, and distribution of crystals in materials science and for predicting the onset of phase changes in various systems.