Molecular Dynamics Simulations of Melting and Recrystallization of Aluminum Nanoparticles

We developed a method that allows us to create simulated aluminum nanoparticles of different sizes and with a variety of crystalline compositions by melting and recrystallizing the nanoparticles at various cooling rates. By varying the cooling rate of the nanoparticle and using different initial seeds, we can produce simulated aluminum nanoparticles with any natural crystalline composition and size. For larger nanoparticles (5 and 4 nm in diameter), we find that slower cooling rates are necessary to obtain a more ordered face-centered cubic crystal structure. For smaller crystallized nanoparticles (diameter 3.5 nm), there is an increase in the proportion of the hexagonal close-packed crystal structure compared to the face-centered cubic crystal structure in the resulting nanoparticle. The smallest crystallized nanoparticles (diameter 3 nm) have a predominantly amorphous structure. We also occasionally observed the formation of an atypical crystalline state for the chosen aluminum potential model. Potentially, our technique can be applied to any material of choice as long as it can be heated up and cooled down (crystallized). Our method can be used to create aluminum (or any other material) nanoparticles of various sizes and different crystalline compositions for further use in computational studies. In addition, this method can be used to test new potential interaction models for possible pitfalls and atypical crystalline structures, which might lead to the improvement of interatomic potential models, especially for nanoparticles.