TY - JOUR
T1 - Adsorption and incorporation of transition metals at the magnetite Fe3O4(001) surface
AU - Bliem, Roland
AU - Pavelec, Jiri
AU - Gamba, Oscar
AU - McDermott, Eamon
AU - Wang, Zhiming
AU - Gerhold, Stefan
AU - Wagner, Margareta
AU - Osiecki, Jacek
AU - Schulte, Karina
AU - Schmid, Michael
AU - Blaha, Peter
AU - Diebold, Ulrike
AU - Parkinson, Gareth S.
PY - 2015
Y1 - 2015
N2 - The adsorption of Ni, Co, Mn, Ti, and Zr at the (root 2 x root 2)R45 degrees-reconstructed Fe3O4(001) surface was studied by scanning tunneling microscopy, x-ray and ultraviolet photoelectron spectroscopy, low-energy electron diffraction (LEED), and density functional theory (DFT). Following deposition at room temperature, metals are either adsorbed as isolated adatoms or fill the subsurface cation vacancy sites responsible for the (root 2 x root 2)R45 degrees reconstruction. Both configurations coexist, but the ratio of adatoms to incorporated atoms depends on the metal; Ni prefers the adatom configuration, Co and Mn form adatoms and incorporated atoms in similar numbers, and Ti and Zr are almost fully incorporated. With mild annealing, all adatoms transition to the incorporated cation configuration. At high coverage, the (root 2 x root 2)R45 degrees reconstruction is lifted because all subsurface cation vacancies become occupied with metal atoms, and a (1 x 1) LEED pattern is observed. DFT+U calculations for the extreme cases, Ni and Ti, confirm the energetic preference for incorporation, with calculated oxidation states in good agreement with photoemission experiments. Because the site preference is analogous to bulk ferrite (XFe2O4) compounds, similar behavior is likely to be typical for elements forming a solid solution with Fe3O4.
AB - The adsorption of Ni, Co, Mn, Ti, and Zr at the (root 2 x root 2)R45 degrees-reconstructed Fe3O4(001) surface was studied by scanning tunneling microscopy, x-ray and ultraviolet photoelectron spectroscopy, low-energy electron diffraction (LEED), and density functional theory (DFT). Following deposition at room temperature, metals are either adsorbed as isolated adatoms or fill the subsurface cation vacancy sites responsible for the (root 2 x root 2)R45 degrees reconstruction. Both configurations coexist, but the ratio of adatoms to incorporated atoms depends on the metal; Ni prefers the adatom configuration, Co and Mn form adatoms and incorporated atoms in similar numbers, and Ti and Zr are almost fully incorporated. With mild annealing, all adatoms transition to the incorporated cation configuration. At high coverage, the (root 2 x root 2)R45 degrees reconstruction is lifted because all subsurface cation vacancies become occupied with metal atoms, and a (1 x 1) LEED pattern is observed. DFT+U calculations for the extreme cases, Ni and Ti, confirm the energetic preference for incorporation, with calculated oxidation states in good agreement with photoemission experiments. Because the site preference is analogous to bulk ferrite (XFe2O4) compounds, similar behavior is likely to be typical for elements forming a solid solution with Fe3O4.
U2 - 10.1103/PhysRevB.92.075440
DO - 10.1103/PhysRevB.92.075440
M3 - Article
SN - 1098-0121
VL - 92
JO - Physical Review B (Condensed Matter and Materials Physics)
JF - Physical Review B (Condensed Matter and Materials Physics)
IS - 7
M1 - 075440
ER -