Size-Dependent Melting Properties of Small Tin Particles: Nanocalorimetric Measurements

For the first time, the latent heat of fusion ΔH_m for Sn particles formed by evaporation on inert substrate with radii ranging from 5 to 50 nm has been measured directly using a novel scanning nanocalorimeter. A particle-size-dependent reduction of ΔH_m has been observed. An ``excluded volume'' is introduced to describe the latent heat of fusion from the enhanced surface melting of small particles. Melting point depression has also been found by our nanocalorimetric technique.