Surface reconstruction of W₂C(0001)
Takashi Aizawa1, Shunichi Hishita, Takaho Tanaka
1National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan. AIZAWA.Takashi@nims.go.jp
Abstract:
A single crystal surface of ditungsten carbide, W(2)C(0001) was investigated using low-energy (LEED) and high-energy electron diffraction, Auger electron spectroscopy, x-ray photoelectron spectroscopy (XPS), and high-resolution electron energy loss spectroscopy (HREELS). A new reconstruction, √13 x √13R ± 13.9◦, was found as a clean surface structure after annealing the W(2)C at > 1900 K. The surface carbon content is shown as larger than that in the bulk. Our preliminary results showed that the same structure is realized also on WC(0001). The same surface periodicity is described for an Mo(2)C(0001) LEED pattern in the literature. This reconstruction phase is presumably common on the (0001) surface of hexagonal group-6 transition-metal carbides. In the off-specular HREELS, an atomic vibration of 44.8 meV (361 cm( - 1)) appeared within the gap energy region of the bulk phonon bands, which was assigned to a surface carbon vibration perpendicular to the surface. One possible explanation of the low vibrational frequency is very low adsorption height of the surface carbon atoms.
Related Concept Videos
Deformations in a Transverse Cross Section
As the material stretches, it expands or contracts in orthogonal directions to the load. This phenomenon varies...
Newman Projections
The organic molecules rotate across the single bonds leading to numerous temporary three-dimensional structures of varying energy known as conformers.
Electron Microscope Tomography and Single-particle Reconstruction
Electron Tomography
Electron tomography can be performed either in TEM or STEM (scanning transmission...
Superposition Theorem
Imperfections in Crystal Structure: Point, Line and Plane Defects
Gauss's Law: Planar Symmetry

