A Double Hard Sphere Model of Liquid Semi-Metals: Applications to Bismuth and Tin

Abstract

The double hard sphere model previously used to calculate the interference functions for liquid Ge, Sb and Ga has now been applied to Sn and Bi. The main features of the observed interference functions just above the melting points have been reproduced, within experimental error, by the superposition of two different partial interference functions represented by hard sphere functions with packing densities of 0.475 and 0.470 for Sn and 0.430 and 0.400 for Bi and respective hard sphere diameters; 3.030 Å and 2.420 Å: 3.335 Å and 2.450 Å. The model has been developed to give a qualitative picture of the bonding in the liquid with the short distance associated with possible overlap of p orbitals. Further, this model has been shown to be in keeping with an alternative employing a ledge type interatomic potential by referring to the measured compressibilities.