Valence band spectra of 4d and 5d silicides

Abstract

A full study of the electronic structure of 4d and 5d silicides (RuSi, RhSi, PdSi, OsSi, IrSi, , PtSi) is undertaken including XPS VB and XES ( and ) measurements and LMTO band structure calculations. It is found that d bands which dominate the density of states are more localized with increasing atomic number Z of the transition metal. A strong hybridization between silicon 3p and transition metal d states occurs over the entire valence band. Si 3s states are found to be not mixed with Si 3p and nd states but Si 3d states participate in bonding and hybridize with transition metal d states. The non-bonding character of the majority of nd states is not confirmed for 4d and 5d silicides.

High pressure stability of the monosilicides of cobalt and the platinum group elements

“…The athermal high pressure study of the stability and the electronic structure of cobalt monosilicide and the monosilicides of the platinum group elements extends the results of previous theoretical and experimental studies at 0 GPa and ambient conditions [7,10,11,16,26,30,32]. RuSi and OsSi adopt the same low pressure (e-FeSi) and high pressure (CsCl) structures as FeSi, and show relatively comparable semiconductor electronic behaviour.…”

“…Because the electronic properties are directly linked to the structure adopted by the material, we observe important changes in the electronic behaviour, notably around the Fermi energy. The DOS at 0 GPa are in agreement with the results of Yarmoshenko et al [30] with a first group of valence electrons between $ À15 eV and $ À8 eV (relative to the Fermi energy), mainly composed of the silicon's s states. A second group is observed between $ À8 eV and the Fermi energy, which is largely composed of the transition metal's nd electrons (where n is the period of the transition metal) hybridized with the silicon's p electrons.…”

“…They remain metals whatever the structure adopted. The electronic properties of the transition metal monosilicides studied show stronger localization of the d electrons in 4d metals than in 5d metals, and the hybridization between the silicon's 3s and 3p electrons with metal's nd electrons, observed by Imai and Watanabe [10] and Yarmoshenko et al [30] seems to persist at high pressure.…”

“…Lastly, PdSi remains a metal in its low pressure MnP structure and in its high pressure P4=nmm structure. the comparison between the electronic DOS at 0 GPa and at 25 GPa shows that the hybridization between the silicon's s and p electrons and the transition metal's d electrons observed at ambient conditions by Yarmoshenko et al [30] persists when the pressure increases. Moreover for the same structure, the ranges of energies occupied by the electrons increase and the electronic bands become wider when the pressure increases, implying a stronger delocalization of the electrons and a higher conductivity for the material.…”

X-ray diffraction analysis of an osmium silicide epilayer grown on Si(100) by molecular beam epitaxy

“…This resulted in poor adhesion of osmium to the silicon substrate [8]. A mechanical alloying technique has also been used to prepare osmium silicides [9]. Very thin osmium films were formed by electroless deposition in a water solution of osmium tetraoxide, ammonia citrate, and sodium hypophosphite [6,10] and then converted to silicides by thermal processing at 600-1000 C in a reducing atmosphere containing 10% of H in Ar.…”