The lattice spacings of lead-rich substitutional solid solutions

Abstract

The lattice-spacing/composition curves for the lead-rich alloys of lead with antimony, bismuth, tin, indium, thallium, cadmium and mercury have been determined. Only bismuth expands the lead lattice. The distortions produced by equiatomic percentages of solute depend on the relative atomic volumes and relative valencies of the solute and solvent metals. Thus, for the solute metals of the second long period of the Periodic Table, the contractions produced by equal atomic percentages of solute decrease in the order cadmium, indium, tin, antimony; this is also the order in which the group valencies and the atomic volumes of the solute metals increase. Similarly, for mercury, thallium and bismuth, the contraction caused by mercury is greater than that caused by the same atomic percentage of thallium, while bismuth, the only solute for which the atomic volume is greater than that of lead, expands the lattice. The results are discussed with particular reference to the effect on lattice-spacing relationships of differences in atomic size and valency between the solute and solvent metals. :No simple correlations are observed; it is concluded that lattice spacings in lead alloys are influenced by some factor connected with the electronic structures of the underlying ions of the component metals, in addition to factors already recognized in alloy systems based on solvent metals of lower valency and smaller atomic number.