Computation of total and partial structure factors, coordination number, and compressibility with self- and mutual-diffusion coefficients of Hg-in alloy

Abstract

Hg-In alloy consisting of Hg, which shows several anomalous features in its properties and In, has been studied with a square-well attractive tail as an interaction potential between the atoms in the amalgam. The partial and the total interference functions have been computed with the Lebowitz hard-sphere mixture solution for the Percus-Yevick equation with an attractive square-well potential over a hard-sphere mixture. In addition, the Bhatia-Thoronton correlation functions have also been calculated. From the partial structure factors the number of nearest neighbors has been calculated. All the computed results have been found to be in very good agreement with the x-ray diffraction results obtained by Halder and Wagner [Z. Naturforsch. 22a, 1489 (1967)] except at 62% atomic fraction of indium. All these results were computed purely from the potential parameters of the pure metals. The alloy is found to show a shoulder in the S_NC(K) cross correlation function. This may be due to either compound formation or internal segregation, even though the metals mix freely at all concentrations. The compressibilities at various concentrations of In have been computed from the Kirkwood-Buff formula. The diffusion coefficients have been calculated from Helfand's linear-trajectory principle. The self-diffusion coefficients as evaluated correctly predict them for both metals because of the attractive wells associated with these metals. Thus Hg, in spite of its heavy mass, has a comparatively higher diffusion coefficient than In, which has a lower mass. The melt appears to form a regular solution, as predicted by Bearman and Jones.