The atomic-scale characterization of defects on cleaved vanadium and molybdenum oxide surfaces using STM

Conference · Fri Sep 01 04:00:00 EDT 1995

OSTI ID:94039

Rohrer, G S; Smith, R L ^[1]

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1. Carnegie Mellon Univ., Pittsburgh, PA (United States). Dept. of Materials Science and Engineering

Scanning tunneling microscopy (STM) was used to determine the structure of cleaved, single crystal surfaces of V{sub 2}O{sub 5}, V{sub 6}O{sub 13}, Mo{sub 18}O{sub 52}, and Mo{sub 8}O{sub 23}. Constant current images were recorded in ultrahigh vacuum and in air. By imaging well-defined surfaces that exhibit structural and chemical similarities, and comparing the observations to the know bulk structures, it is possible to establish a reliable interpretation for the contrast in the STM images. A comparison of images from the V{sub 6}O{sub 13}(001) and the V{sub 2}O{sub 5}(001) surfaces clearly shows that the surface V coordination polyhedra that are capped by vanadyl O can be distinguished from those that are not. This allows vacancies in the vanadyl O position to be identified on cleaved V{sub 2}O{sub 5}(001) surfaces. Mo{sub 18}O{sub 52}(001) and Mo{sub 8}O{sub 23}(010) provide models for two different characteristic types of surface/crystallographic shear (CS) plane intersections. The shear in Mo{sub 8}O{sub 23} lies in the (010) surface plane and creates dark contrast along the [001]. The CS planes in Mo{sub 18}O{sub 52}, on the other hand, have components of shear both in and normal to the (100) surface plane and create white contrast parallel to [010]. These standards for contrast identification can be used to identify defects on inhomogeneous surfaces.

• OSTI ID: 94039
• Report Number(s): CONF-941144--; ISBN 1-55899-258-8
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CRYSTAL DEFECTS
ELECTRONIC STRUCTURE
MICROSCOPY
MOLECULAR STRUCTURE
MOLYBDENUM OXIDES
MONOCRYSTALS
STRUCTURAL MODELS
SURFACES
VACANCIES
VANADIUM OXIDES
X-RAY DIFFRACTION