The evolution of the passive films on 2205 duplex stainless steel (2205 DSS) and AISI 316L stainless steel in artificial saliva, and with the addition of fluoride, was studied using electrochemical impedance spectroscopy (EIS) and potentiodynamic measurements. The extent of the passive range increased for the 2205 DSS compared to the AISI 316L in both solutions. The formation of the passive film was studied by EIS at the open-circuit potential (OCP). The passive layers were studied at the OCP by X-ray photoelectron spectroscopy (XPS). The passive films on both materials predominantly contained Cr-oxides, whereas the Fe species were markedly depleted.
COBISS.SI-ID: 24275239
The adsorption of atomic Se on a Fe(1 1 0) surface is examined using the density functional theory (DFT). Selenium is adsorbed in high-symmetry adsorption sites: the -short and long-bridge, and atop sites at 1/2, 1/4, and 1 monolayer (ML) coverages. The long bridge (LB) site is found to be the most stable, followed by the short bridge (SB) and top sites (T). The following overlayer structures were examined, p(2 * 2), c(2 * 2), and p(1 * 1), which correspond to 1/4 ML, 1/2 ML, and 1 ML respectively. Adsorption energy is -5.23 eV at 1/4 ML. Se adsorption results in surface reconstruction, being more extensive for adsorption in the long bridge site at 1/2 ML, with verticaldisplacements between +8.63 and -6.69% -with regard to the original Feposition-, affecting the 1st and 2nd neighbours. The largest displacement inx or y-directions was determined to be 0.011, 0.030, and 0.021 A for atop and bridge sites. Comparisons between Se-adsorbed and pure Fe surfaces revealed reductions in the magnetic moments of surface-layer Fe atoms in the vicinity of the Se. At the long bridge site, the presence of Se causes a decrease in the surface Fe d-orbital density of states between 4 and 5 eV below Fermi level. The density of states present a contribution of Se states at -3.1 eV and -12.9 eV. stabilized after adsorption. The Fe-Fe overlap population decrease and a Fe-Se bond are formed at the expense of the metallicbond.
COBISS.SI-ID: 854186