TiOx thin films grown on Pd(100) and Pd(111) by chemical vapor deposition
2016 (English)In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 649, 80-89 p.Article in journal (Refereed) PublishedText
The growth of ultrathin TiOx (0 <= x <= 2) films on Pd(100) and Pd(111) surfaces by chemical vapor deposition (CVD), using Titanium(IV)isopropoxide (TTIP) as precursor, has been investigated by high resolution photoelectron spectroscopy, low energy electron diffraction and scanning tunneling microscopy. Three different TiOx phases and one Pd-Ti alloy phase have been identified for both surfaces. The Pd-Ti alloy phase is observed at the initial stages of film growth. Density functional theory (DFT) calculations for Pd(100) and Pd(111) suggest that Ti is alloyed into the second layer of the substrate. Increasing the TTIP dose yields a wetting layer comprising Ti2+ species (TiOx, x similar to 0.75). On Pd(100), this phase exhibits a mixture of structures with (3 x 5) and (4 x 5) periodicity with respect to the Pd(100) substrate, while an incommensurate structure is formed on Pd(111). Most importantly, on both surfaces this phase consists of a zigzag pattern similar to observations on other reactive metal surfaces. Further increase in coverage results in growth of a fully oxidized (TiO2) phase on top of the partially oxidized layer. Preliminary investigations indicate that the fully oxidized phase on both Pd(100) and Pd(111) may be the TiO2(B) phase.
Place, publisher, year, edition, pages
2016. Vol. 649, 80-89 p.
Photoemission spectroscopy, Low energy electron diffraction, Scanning tunneling microscopy, TiOx thin films, Pd, Density functional calculations
Condensed Matter Physics
IdentifiersURN: urn:nbn:se:uu:diva-300062DOI: 10.1016/j.susc.2016.02.002ISI: 000379097000013OAI: oai:DiVA.org:uu-300062DiVA: diva2:950762
FunderSwedish Energy Agency, 36642-1Swedish Research Council, 2011-3532 621-2014-4708Carl Tryggers foundation , CTS 12:417The Crafoord Foundation, 20060599