We investigated the relative stability of the amorphous versus crystalline nanoparticles of sizes ranging between $0.8$ and $1.8$ nm. We found that (at variance from bulk systems) at low $T$, small nanoparticles are amorphous and they undergo an amorphous-to-crystalline phase transition at high $T$. On the contrary, large nanoparticles recover the bulklike behavior: crystalline at low $T$ and amorphous at high $T$. We also investigated the structure of crystalline nanoparticles, providing evidence that they are formed by an ordered core surrounded by a disordered periphery. Furthermore, we also provide evidence that the details of the structure of the crystalline core depend on the size of the nanoparticle.

• Received 18 January 2011

DOI:https://doi.org/10.1103/PhysRevB.83.235303