Melting Behaviour of Fractal-Shaped Nanoparticles (the Example of Si–Ge System)

Resumo

The influence of shape on phase equilibria in a two-phase region between liquidus and solidus temperatures has been simulated using Si–Ge nanoparticles as an example. The shape and volume of a particle have been set by its effective radius and fractal dimension. The temperature dependence of the fractal dimension of the phases has been taken into consideration in terms of a simple geometrical model. It has been shown that decreasing the volume of a nanoparticle and its fractal dimension (which corresponds to nanoparticles of a more complicated shape) leads to narrowing down the temperature range of the heterogeneous region, changes in phase transition temperatures and equilibrium compositions of co-existing phases. It has been found that at different temperatures the dependences of the composition of the liquid phase on a particle’s morphology differ which is explained by implementing different mechanisms of reducing the surface energy.