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Transition from Reconstruction toward Thin Film on the (110) Surface of Strontium Titanate.

Wang Z, Loon A, Subramanian A, Gerhold S, McDermott E, Enterkin JA, Hieckel M, Russell BC, Green RJ, Moewes A, Guo J, Blaha P, Castell MR, Diebold U, Marks LD - Nano Lett. (2016)

Bottom Line: Such structures can also be viewed as ultrathin films, epitaxed on a substrate.Whereas SrTiO3 (110) invariably terminates with an overlayer of titania, with increasing density its structure switches from n × 1 to 2 × n.At the same time the coordination of the Ti atoms changes from a network of corner-sharing tetrahedra to a double layer of edge-shared octahedra with bridging units of octahedrally coordinated strontium.

View Article: PubMed Central - PubMed

Affiliation: Institute of Applied Physics, TU Wien , Wiedner Hauptstrasse 8-10/134, 1040 Vienna, Austria.

ABSTRACT
The surfaces of metal oxides often are reconstructed with a geometry and composition that is considerably different from a simple termination of the bulk. Such structures can also be viewed as ultrathin films, epitaxed on a substrate. Here, the reconstructions of the SrTiO3 (110) surface are studied combining scanning tunneling microscopy (STM), transmission electron diffraction, and X-ray absorption spectroscopy (XAS), and analyzed with density functional theory calculations. Whereas SrTiO3 (110) invariably terminates with an overlayer of titania, with increasing density its structure switches from n × 1 to 2 × n. At the same time the coordination of the Ti atoms changes from a network of corner-sharing tetrahedra to a double layer of edge-shared octahedra with bridging units of octahedrally coordinated strontium. This transition from the n × 1 to 2 × n reconstructions is a transition from a pseudomorphically stabilized tetrahedral network toward an octahedral titania thin film with stress-relief from octahedral strontia units at the surface.

No MeSH data available.


Related in: MedlinePlus

Ti L2,3 XASon the 4 × 1 and 2 × 5 surface. (a) Experimental Ti L2,3 XAS measured with AEY (red curve) and SEY (black curve)mode, respectively. (b) Simulated Ti L2,3 XAS of Ti ionsin octahedra (Oh) (gray)and tetrahedra (Td) (black)coordination. The low panel shows the spectra with combination of Oh and Td. (c) Experimental Ti L2,3 XASmeasured with AEY (red) and SEY (black) electron yield on the 2 ×5 surface.
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fig2: Ti L2,3 XASon the 4 × 1 and 2 × 5 surface. (a) Experimental Ti L2,3 XAS measured with AEY (red curve) and SEY (black curve)mode, respectively. (b) Simulated Ti L2,3 XAS of Ti ionsin octahedra (Oh) (gray)and tetrahedra (Td) (black)coordination. The low panel shows the spectra with combination of Oh and Td. (c) Experimental Ti L2,3 XASmeasured with AEY (red) and SEY (black) electron yield on the 2 ×5 surface.

Mentions: Striking differenceswere observed between the AEY and SEY on the 4 × 1 surface (see Figure 2a). Two main peakslocated at 458 and 460 eV correspond to Ti 2p3/2→3d transitions, while an additional shoulder appears at 459 eV inthe SEY (see the black curve in Figure 2a). The shoulder becomes pronounced and the two mainpeaks are significantly weakened in the AEY (see the red curve in Figure 2a). Similar effectswere present in the Ti L2 spectra (2p1/2→3d transitions).43


Transition from Reconstruction toward Thin Film on the (110) Surface of Strontium Titanate.

Wang Z, Loon A, Subramanian A, Gerhold S, McDermott E, Enterkin JA, Hieckel M, Russell BC, Green RJ, Moewes A, Guo J, Blaha P, Castell MR, Diebold U, Marks LD - Nano Lett. (2016)

Ti L2,3 XASon the 4 × 1 and 2 × 5 surface. (a) Experimental Ti L2,3 XAS measured with AEY (red curve) and SEY (black curve)mode, respectively. (b) Simulated Ti L2,3 XAS of Ti ionsin octahedra (Oh) (gray)and tetrahedra (Td) (black)coordination. The low panel shows the spectra with combination of Oh and Td. (c) Experimental Ti L2,3 XASmeasured with AEY (red) and SEY (black) electron yield on the 2 ×5 surface.
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Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4834633&req=5

fig2: Ti L2,3 XASon the 4 × 1 and 2 × 5 surface. (a) Experimental Ti L2,3 XAS measured with AEY (red curve) and SEY (black curve)mode, respectively. (b) Simulated Ti L2,3 XAS of Ti ionsin octahedra (Oh) (gray)and tetrahedra (Td) (black)coordination. The low panel shows the spectra with combination of Oh and Td. (c) Experimental Ti L2,3 XASmeasured with AEY (red) and SEY (black) electron yield on the 2 ×5 surface.
Mentions: Striking differenceswere observed between the AEY and SEY on the 4 × 1 surface (see Figure 2a). Two main peakslocated at 458 and 460 eV correspond to Ti 2p3/2→3d transitions, while an additional shoulder appears at 459 eV inthe SEY (see the black curve in Figure 2a). The shoulder becomes pronounced and the two mainpeaks are significantly weakened in the AEY (see the red curve in Figure 2a). Similar effectswere present in the Ti L2 spectra (2p1/2→3d transitions).43

Bottom Line: Such structures can also be viewed as ultrathin films, epitaxed on a substrate.Whereas SrTiO3 (110) invariably terminates with an overlayer of titania, with increasing density its structure switches from n × 1 to 2 × n.At the same time the coordination of the Ti atoms changes from a network of corner-sharing tetrahedra to a double layer of edge-shared octahedra with bridging units of octahedrally coordinated strontium.

View Article: PubMed Central - PubMed

Affiliation: Institute of Applied Physics, TU Wien , Wiedner Hauptstrasse 8-10/134, 1040 Vienna, Austria.

ABSTRACT
The surfaces of metal oxides often are reconstructed with a geometry and composition that is considerably different from a simple termination of the bulk. Such structures can also be viewed as ultrathin films, epitaxed on a substrate. Here, the reconstructions of the SrTiO3 (110) surface are studied combining scanning tunneling microscopy (STM), transmission electron diffraction, and X-ray absorption spectroscopy (XAS), and analyzed with density functional theory calculations. Whereas SrTiO3 (110) invariably terminates with an overlayer of titania, with increasing density its structure switches from n × 1 to 2 × n. At the same time the coordination of the Ti atoms changes from a network of corner-sharing tetrahedra to a double layer of edge-shared octahedra with bridging units of octahedrally coordinated strontium. This transition from the n × 1 to 2 × n reconstructions is a transition from a pseudomorphically stabilized tetrahedral network toward an octahedral titania thin film with stress-relief from octahedral strontia units at the surface.

No MeSH data available.


Related in: MedlinePlus