X-Ray Diffraction Analysis of Liquid Hg, Sn, Zn, Al and Cu

A vertical X-ray diffractometer with a high temperature chamber has been constructed for scattering experiments on liquid metals. The liquid samples can be measured with a monochromatic beam in a horizontal position over a wide angular range up to 80° in scattering angle θ using a scintillation counter and up to 75° using a solid state detector. Five metals, Hg, Sn, Zn, Al and Cu have been reinvestigated at temperatures near and above their melting points in reductive gas atmospheres of purified helium and hydrogen. Their scattering curves as well as the results of their radial distribution analysis are presented. Particular attention has been paid to the data processing, which includes corrections for measured and calculated intensities, absorption correction for surface curvature and correction for data termination at a finite angle. It has been found necessary to subtract the double scattering contribution from the scattering data of liquid aluminium to obtain true values in electron units. Comparison with the theoretical liquid structure factors shows that the simple model of hard spheres in the Percus-Yevick approximation [32] adequately describes liquid copper and liquid aluminium, which have symmetrical main interference peaks, but fails to describe such liquids as Hg, Sn and Zn, which have a more complex structure in the liquid state.