The size dependence of the melting point of small particles of tin

The size dependence of the melting point of tin has been studied by means of transmission electron diffraction and microscopy. In accordance with the observations of other workers, it has been found that the melting point of a spherical particle of tin decreases as the radius Rm of the particle decreases. However, the decrease does not depend linearly on 1/Rm. The experimental results are explained in terms of a thermodynamic treatment which allows for the fact that a liquid cannot be subdivided indefinitely. The theory ceases to give correct results for the melting point of particles with radii less than about 50 Å, the calculated temperatures being less than those observed. For particles to which the theory is applicable it is found that the surface tension at the interface between solid and liquid tin is σ1 = 62·2 ± 10 dyn cm-1.