Different morphologies of aluminum nanoclusters: Effect of pressure on solid-liquid phase transition of the nanoclusters using molecular dynamics simulations

In this work, we have simulated the melting points of Al55 nanoclusters in the icosahedral and cuboctahedral and for the Al54 in the decahedral morphologies at different exerted pressures of 0.0001, 0.1, 0.5, 1, 2, and 3 GPa. We have investigated the effect of the exerted pressure on some of the thermodynamics and structural properties of the Al nanoclusters with the three different morphologies. Our results indicated that the thermal stability of the Al nanocluster in the icosahedral morphology is greater than other structures from low pressures to 2 GPa. After that, the Al nanocluster in the cuboctahedral morphology is more stable than the others. Our results also showed that the molar enthalpy and molar volume changes of melting are almost constant for all of the Al nanoclusters as the external pressure increase. Our structural investigations indicated that the Al nanocluster in the icosahedral morphology shows a solid-solid transformation to somewhat HCP symmetry near the melting point. The Al nanocluster in the cuboctahedral morphology shows a transformation to icosahedral morphology with increasing the temperature, then it changes to somewhat HCP structure near the melting point. The Al nanocluster in the decahedral morphology shows also a transformation to icosahedral morphology with increasing the temperature, then it changes to an amphorous-like structure near the melting point. These transformations exist for the Al nanoclusters at the different pressures.