Size-dependent melting point depression of nanostructures: Nanocalorimetric measurements

The melting behavior of 0.1-10-nm-thick discontinuous indium films formed b y evaporation on amorphous silicon nitride is investigated by an ultrasensi tive thin-film scanning calorimetry technique. The films consist of ensembl es of nanostructures for which the size dependence of the melting temperatu re and latent heat of fusion are determined. The relationship between the n anostructure radius and the corresponding melting point and latent heat is deduced solely from experimental results (i.e., with no assumed model) by c omparing the calorimetric measurements to the particle size distributions o btained by transmission electron microscopy. It is shown that the melting p oint of the investigated indium nanostructures decreases as much as 110 K f or particles with a radius of 2 nm. The experimental results are discussed in terms of existing melting point depression models. Excellent agreement w ith the homogeneous melting model is observed.