Partial Interference and Atomic Distribution Functions of Liquid Silver—Tin Alloys

Abstract

The x-ray scatterings from liquid Ag–Sn alloys previously measured at temperatures 100°C above the respective liquidus temperatures have been reanalyzed. The total-interference functions (also called structure factors) I(K), where K=4π sinθ/λ, were first refined and then used to calculate the partial-interference functions Iij(K), assuming that they are approximately independent of the atomic concentrations. The least-squares analysis with five different atomic concentrations of Sn, i.e., 18.5, 25, 36.5, 50, and 68.5 at.%, yielded three Iij(K). The Fourier transform of Iij(K) leads to the partial radial distribution function (RDF)=4πr2ρij(r)/cj, and the reduced distribution function Gij(r)=4πr[ρij(r)/cj—ρ0], where ρij(r) is the partial radial density, cj is the atomic concentration of the j-atoms and ρ0 is the average atomic density. Thus calculated Iij(K) and Gij(r) were used to reproduce the measured I(K) and their corresponding G(r), and a remarkably good agreement was found between the measured and calculated values. Judging from the observed agreement, it can be concluded that for liquid Ag–Sn alloys the partial ISnSn(K), IAgAg(K), and ISnAg(K) are not influenced by the relative abundance of the elements. The resistivity of the alloys obtained with Iij(K) and the pseudopotential elements Ui(K) agrees well with those measured experimentally.