Surface atomic structure of reconstructedVC0.8(111) studied with scanning tunneling microscopy

Abstract

Scanning tunneling microscopy has been performed on the reconstructed polar surface of substoichiometric VC08O(111). A mixture of (8X1) and (&3X&3)R30' reconstructed areas was found. The (8X1) periodicity could be determined to be the result of a square-lattice surface layer superimposed on the hexagonal substrate. As this square lattice must have its origin in strong and directed in-0 plane bonds with the relatively large length of about 2.9 A, it can be deduced to consist of vanadium atoms. Lateral positions of these vanadium surface atoms with respect to the substrate are suggested from the measured surface corrugation. The (&3X&3)R30' structure was found in small triangular areas which can, due to the measured step heights between the two reconstructions, be believed to be carbon terminated. The occurrence of a reconstructed surface with a reduced atomic concentration is in contrast to what is known for TiC(111) and NbC (111), both having stable (1X1) surfaces. A qualitative explanation for this difference is suggested.

Redox Properties of Titanium Oxides on Pt3Ti

“…6 The main chamber of this system is equipped with an Omicron microscope and data-handling routines.…”

“…Scanning tunneling measurements (STM) were done in a different ultrahigh vacuum system, likewise equipped with an intergrated preparation chamber with LEED optics. 6 The main chamber of this system is equipped with an Omicron microscope and data-handling routines.…”

Layer-Stacking, Defects, and Robust Superconductivity on the Mo-Terminated Surface of Ultrathin Mo2C Flakes Grown by CVD

“…According to the STM image taken near the step edges (Figure S3), the height differences between the Moterminated terraces were measured to be multiples of 2.35 ± 0.03 Å, fitting well with the thickness of a single Mo−C bilayer (2.36 Å) in the orthorhombic system. 23,24 Besides the Mo lattice, some defects appear as dark holes with a depth of 1.14 Å, which can be attributed to the Mo vacancies (Figure S4). Figure 1d shows an atomic model for the (100) surface, and the corresponding STM topographies measured with different bias voltages are displayed in Figure 1e−g.…”

Surface structures on sputtered/annealed WC(0001)

“…The VC 0.80 (111) surface presents an interesting exception within the NaCl structure transition metal carbides since it reconstructs in a metal terminated (8 × 1) structure together with a carbon terminated ( √ 3 × √ 3)R30 • structure after sputtering and annealing above 900 • C [15]. At lower annealing temperatures (700-900 • C) a non-reconstructed meta-stable vanadium terminated (1 × 1) surface was obtained [16].…”