Electronic structure of SnF3: An example of valence skipper which forms charge density wave
Abstract In the present study we calculated the electronic structure of the valence skipping compound SnF 3 and BaBiO 3 from first-principles. We confirmed that the charge-density-wave (CDW) is formed in SnF 3 , and the Sn atoms in two crystallographic different sites take the valence Sn 2+ and Sn 4+ . Structure optimization study reveals that this CDW is stable, though the atomic position is slightly different from the experimental data. This behavior is in contrast with the case of BaBiO 3 , where the structure optimization leads to the uniform state, which means that two Bi sites are equivalent. The CDW state is hard in SnF 3 , which means that the CDW gap is large enough and it is difficult to melt this CDW order.
Abstract X-ray photoelectron spectroscopy was applied to analyze the surface composition of sodium dihydrogenphosphate/ferric oxide systems and montmorillonite which were chosen as model sediment (soil) systems. Striking differences in the photoelectron emission intensities for certain elements were observed for samples of differing preparations and where the bulk composition of elements were retained. Adsorbed phosphate ion was persistent on ferric oxide surface against repeated leaching by water where sodium ion was lost completely from the surface.