Physical properties of icosahedral and glassy Pd−U−Si alloys

The transformations of glassy Pd₆₀U₂₀Si₂₀ alloys into an icosahedral state with quasicrystalline order and into the crystalline state have been studied by differential scanning calorimetry and X-ray diffraction. In addition, the electrical resistivity, the Hall coefficient and the magnetic susceptibility have been measured to high temperatures. The electronic structure has been investigated by photoelectron spectroscopy and the top surface layers have been probed by ion scattering spectroscopy. The physical properties in the icosahedral and glassy phase are similar. Comparisons with other uranium rich or dilute alloys are made in order to study the valence change or the development of a magnetic moment for uranium. Finally, the novel scanning tunneling microscope has been used to study the topography and the local tunneling barrier height with the aim of correlating micromorphology with local chemical structure.Dedicated to professor Harry Thomas on the occasion of his 60th birthday